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Compound jetting from bubble bursting at an air-oil-water interface


High-speed imaging of bubble bursting

The bubble bursting dynamics at an oil-covered aqueous surface is observed by two synchronized high-speed cameras from side views above and below the liquid surface (Fig. 1a). No surface-active material is added in any liquid. The gas bubble approaches the oil-covered aqueous surface after being released. Then the bubble rests at the air–oil–water interface with a cap consisting of water and oil films after its initial oscillation has died down (Fig. 1b), and finally bursts. The bubble shape at rest is almost unchanged in the pure water and different oily cases. We fixed the equivalent radius of the bubble as R = 1.67 mm and used 5–1000 cSt silicone oils in our experiments (Table 1). When the oil layer thickness h is larger than a critical thickness hc (≈1.2R), the water film on the bubble cap ruptures first, and subsequently the whole bubble enters the oil layer. In such a regime, no jet droplets are emitted by bubble bursting at the viscous oil layer in the experiments (Supplementary Fig. 1 and Supplementary Movies 13). While for h ≤ hc, the oil and water films on the bubble cap rupture simultaneously, and the subsequent cavity collapse results in a compound multiphase jet that ejected droplets. Therefore, all experiments were performed with h ≤ hc (Fig. 1c).

Fig. 1: Experimental setup, sketch of a still bubble at an oil-covered aqueous surface and regime map of bubble bursting jets.
figure1

a Schematic of the experimental apparatus. The air bubble with an equivalent radius of R = 1.67 mm is generated by a needle at the bottom of the container with a syringe pump, and it rises to the water surface covered by an oil layer with a thickness h. The bubble rests at the oil-covered aqueous surface, and then bursts, which is recorded by two computer-controlled synchronized high-speed cameras with LED illumination. b Close-up sketch of an air bubble with radius R resting at an aqueous surface covered by an oil layer with a thickness h, which typifies an organic-enriched, structurally complex interface. c Regime map of bubble bursting jets at an oil-covered aqueous surface regarding the oil viscosity μo and the oil layer thickness h, showing the boundary between no jet droplet and jet droplet of the bubble bursting. Jet droplets only occur when the oil layer thickness is smaller than a critical thickness hc, where the oil and water layers rupture simultaneously and oily jet droplets are ejected into air. When h > hc, the water film ruptures first and then the whole bubble enters the oil layer, and the subsequent bubble bursting jet does not eject any oily aerosol droplets (Supplementary Fig. 1 and Supplementary Movies 13).

Table 1 Physical properties of the liquids used in the experiments.

Oily jetting

In our experimental system, after the simultaneous rupture of the oil and water films on the bubble cap, the cavity collapses, with capillary waves propagating downwards and finally focusing at the cavity nadir. Then the curvature of the interface at the bubble nadir reverses, generating an upward Worthington jet20 that finally breaks up due to Rayleigh-Plateau instability and disperses myriads of droplets, known as jet droplets, into air. Surprisingly, unlike the bubble bursting jet from a clean water surface3,21,22, a long and thin liquid thread appears during the jet pinch-off from an oil-covered aqueous surface (Fig. 2b–d). Such a feature is a typical characteristic of highly viscous fluid pinch-off23,24, which indicates the formation of an oily jet. In addition, we observed dumbbell-shaped jet droplets produced by such a compound jet (Supplementary Fig. 2 and Supplementary Movie 4), which is another distinct feature compared with bubble bursting at a clean water surface. These droplets remain uncoalesced until they fall onto the oil layer with a much longer life time compared with pure water droplets. We believe the oil coating delays the droplet coalescence, as a further evidence for the compound droplets from the oily jetting. In addition, by dispersing tracer microparticles into the oil layer and imaging the particles from the dried top jet droplet collected on a glass slide, we directly evidenced the presence of oil in the jet droplets (Supplementary Fig. 3), and the top jet droplet could contain an oil volume fraction of up to 83% (see SI for the calculation).

Fig. 2: Snapshots of bubble bursting jetting and the measured jet tip radius and velocity.
figure2

Side-view snapshots of jet formation during bubble bursting at the aqueous surface (a) without an oil layer, and covered by a layer of (b) 5 cSt silicone oil, h/R = 0.6, (c) 500 cSt silicone oil, h/R = 0.6, and (d) 500 cSt silicone oil, h/R = 1.2. R = 1.67 mm in the experiments. Scale bar = 1 mm. t = 0 represents the beginning of bubble bursting when a hole nucleates in the bubble cap. An oily jet is generated (column 2 of ad) following the cavity collapse, which becomes smaller but faster with the increasing viscosity and thickness of the oil layer. A thin oily thread is observed in all oily cases (highlighted in column 3 of bd). Dependencies of (e) the jet tip radius rj and (f) jet tip velocity vj on the oil layer thickness h for different oil viscosities. rj and vj are measured when the jet tip crosses the undisturbed air–oil interface. Error bars are calculated as the standard deviations of data of at least 10 runs.

It has been well established that the jet formation after the cavity collapse controls the follow-up droplet generation, including the jet droplet size and velocity, as shown in prior work for bubble bursting at a single liquid surface25,26. In particular, the jet tip radius and velocity show similar trends as the top jet droplet radius and velocity26. Therefore, we mainly focus on characterizing the jet dynamics in the current work, as a first step to inform the interplay between bubbles and a compound interface. The radius, rj, and velocity, vj, of the jet tip are measured when the tip crosses the horizontal level of undisturbed air–oil interface (Fig. 2a). Remarkably, we observe that the oily jet is thinner and travels faster, i.e., rj decreases and vj increases with increasing oil viscosity (μo) and oil layer thickness (h) (Fig. 2e, f), and eventually smaller oily jet droplets are ejected with a faster speed compared with the case of an air-water surface (Fig. 2a–d). The radius and velocity of the top jet droplet at the moment of detachment are also measured, as shown in Supplementary Fig. 4. Meanwhile, both the jetting height and jet droplet number increase with μo and h (Supplementary Movie 5).

Previous studies show that the jet dynamics of bubble bursting at a clean liquid surface is mainly controlled by two dimensionless numbers, e.g., the Bond number Bo = ρgR2/γ and Ohnesorge number

$${{{{{mathrm{Oh}}}}}}=frac{mu }{sqrt{rho gamma R}},$$

(1)

where ρ, μ, γ indicate liquid density, dynamic viscosity, and interfacial tension, respectively, and g is the gravitational acceleration21,25,27. Under conditions in which Bo (effect of gravity relative to surface tension) exceeds 3, no jet droplets are produced because of the influence of gravity on the cavity shape. Similarly, when Oh (effect of viscosity to inertial and surface tension) exceeds 0.03–0.04, jet droplets are not produced since viscous stresses suppress jetting by damping out the inertial capillary waves driving the motion28,29.

Using the silicone oil properties in our current experiments (Table 1), Bo = 1.2−1.4 and Oh = 0.03−5, no jet droplet is expected by bubble bursting at the surface of a bulk silicone oil28. However, the ejection of the oily jet droplet is observed in our experiment, even if the oil layer viscosity is high. Therefore, for a compound interface with a viscous oil layer on top of the water surface, bubble bursting jet can actually eject droplets containing the very viscous oil component as shown by our study. This feature is not predicted by the maximum viscous limit, considering Oh, for jet droplets to form at a clean bulk liquid surface in prior work. This indicates that for an organic-enriched interface, such as the sea-surface microlayer, the highly viscous surface organic matter may be ejected into the atmosphere through the break-up of a bubble bursting jet, raising the question of how the oils at the aqueous surface transport to the jet and jet droplets produced by a clean gas bubble.

Oil spreading on cavity surface

Here we show that the formation of oily jets results from the spreading of oils along the surface of the collapsing cavity. For the bubble dynamics at an air–oil–water interface, it is important to consider physicochemical interaction between oil and water molecules, as highlighted by our previous work about nanoemulsions produced by bubble bursting16,30. The bubble cavity surface below the oil–water interface before bubble bursting is initially oil-free as shown in Fig. 1b. Given the positive spreading coefficient Δγ = γwa − γoa − γow > 0 (Table 1) in the complete-wetting state between silicone oil and water, the oil spontaneously spreads along the cavity surface towards the bubble nadir once the cap ruptures. In addition, it has been shown by previous studies31,32 that the spreading of a silicone oil droplet on an aqueous surface exhibits two distinct spreading fronts with non-uniform thicknesses, i.e., a faster microscopic front connecting to a slower macroscopic bulk edge. From the high-speed imaging as shown in Fig. 3 and Supplementary Fig. 5, a macroscopic oil edge propagating along the cavity surface is observed. In addition, the propagation of the macroscopic spreading edge is slower with increasing oil viscosity (Fig. 3b, c) but basically unaffected by the oil layer thickness (Fig. 3c, d). For instance, the macroscopic spreading edge of 100 cSt oil arrives at the cavity nadir at the onset of jet formation (t = 2.8 ms in Fig. 3b), and that of 1000 cSt oil is still far away from the cavity nadir (t = 3.6 ms in Fig. 3c, d) when the nadir curvature reverses.

Fig. 3: Top-view snapshots of oil spreading on the cavity surface during bubble bursting at the aqueous surface.
figure3

The water surfaces shown here are (a) clean, and covered by a layer of (b) 100 cSt silicone oil, h/R = 0.8, (c) 1000 cSt silicone oil, h/R = 0.8, and (d) 1000 cSt silicone oil, h/R = 1.2. Scale bar = 1 mm. Comparing with the pure water case (a), a macroscopic oil edge (marked by red arrows) along the cavity after the cap rupture at an oil-covered aqueous surface is clearly observed, which is generated by oil spreading in the complete-wetting state (bd). The macroscopic oil edges can be distinguished since they typically show asymmetric and irregular morphology, while the capillary waves from cavity collapse show axisymmetric and smooth patterns. Additional evidence is shown in Supplementary Fig. 5 with tracer particles to assist visualization of the macroscopic oil edges.

While we cannot directly visualize the microscopic front ahead of the macroscopic oil edge since the adjacent oil-film thickness is at the order of O(1 nm)33, the surface-tension-driven spreading speed of the microscopic oil front can be estimated by balancing the net driving force and the viscous force that developed at the boundary layer of the supporting fluid. Then the time for the microscopic oil front reaching the bubble cavity nadir can be estimated as31,32,34

$${t}_{{{{{{mathrm{s}}}}}}} sim {left(frac{{mu }_{{{{{{mathrm{w}}}}}}}{rho }_{{{{{{mathrm{w}}}}}}}{R}^{4}}{{{Delta }}{gamma }^{2}}right)}^{1/3},$$

(2)

while the time of cavity collapse can be written as the capillary time25,35 calculated based on the effective surface tension of the air–oil–water interface γe = γoa + γow36,

$${t}_{{{{{{mathrm{c}}}}}}} sim {left(frac{{rho }_{{{{{{mathrm{w}}}}}}}{R}^{3}}{{gamma }_{{{{{{mathrm{e}}}}}}}}right)}^{1/2}.$$

(3)

In our experiments, we find ts ≈ tc ≈ O(1 ms). The comparable time scales indicate that the microscopic oil front is able to reach the base of the cavity and the compound jet can form, confirming our observations. In addition, we find that a more viscous substrate liquid than water weakened the effect of the oil layer on the jet dynamics (Supplementary Fig. 6), presumably due to the slower spreading of the oil film (larger ts) on the cavity surface, showing the important role of the oil spreading dynamics.

Cavity collapse and capillary wave propagation

We further investigate how the oil spreading at the cavity surface modifies the jet dynamics. It has been stated that the capillary wave propagation during cavity collapse plays an important role in the jet dynamics produced by bubble bursting. During cavity collapse, the rim retraction after the bubble cap rupture excites a series of capillary waves propagating along the cavity surface (Fig. 4). The capillary waves with relatively smaller wavelengths travel faster and are more rapidly attenuated by viscosity25,27. The dominant capillary wave selected by viscous attenuation, i.e., the capillary wave with the shortest wavelength not attenuated by viscosity during cavity collapse, can successfully propagate to the bubble nadir and makes the cavity collapse to a truncated cone, which triggers the ejection of a jet25.

Fig. 4: Side-view snapshots of cavity collapse during bubble bursting.
figure4

The water surfaces shown here are (a) clean, or covered by a layer of (b) 100 cSt silicone oil, h/R = 0.8, (c) 1000 cSt silicone oil, h/R = 0.8, and (d) 1000 cSt silicone oil, h/R = 1.2. The equivalent bubble radius R = 1.67 mm in the experiments. Scale bars represent 1 mm. The capillary waves during cavity collapse are progressively damped in the oily cases compared with those in the pure water case (column 4 as the zoom-in images of the blue square zones in column 2), which results in a sharper tip at the cavity nadir in the oily cases (column 3), indicating the additional damping effect from the oil layer.

Considering the essential role of capillary wave dynamics, we measured the selected dominant wave speed, vd, as the propagation speed when the last wave crest crosses the position with an angle of π/4 corresponding to the vertical cavity axis following the previous study25. We found that vd/vc = 7.2 ± 1.3 which is almost unaffected by the oil layer (Fig. 5), with the inertial capillary velocity vc calculated based on γe as

$${v}_{{{{{{mathrm{c}}}}}}}={left(frac{{gamma }_{{{{{{mathrm{e}}}}}}}}{{rho }_{{{{{{mathrm{w}}}}}}}R}right)}^{1/2}.$$

(4)

This velocity ratio is consistent with that in previous numerical study on bubble bursting jetting at a clean liquid surface as vd/vc ≈ 5, which is independent of Oh37. The wavelength of the selected dominant wave, λd, which was suggested to be estimated as the minimum radii of curvature of the capillary waves, was found to increase with Oh due to the larger viscous attenuation25,37. An increasing λd can shorten the lower base of the truncated cone-shaped cavity, and hence decreases the jet radius and increases the jet velocity when Oh < 0.03 for bubble bursting at a clean liquid surface25,26,37. Though we could not precisely measure the radii of curvature of the capillary waves due to the spatial resolution limit of the experimental images, a smaller radius at the lower base of the truncated cone-shaped cavity is observed at the moment of jet formation when increasing the oil viscosity and layer thickness (column 3 in Fig. 4), suggesting a larger λd. Meanwhile, we found that while the bubble cavity shapes remain similar, the amplitudes of the capillary waves are noticeably damped by the presence of oil (Fig. 4), and the damping effect increases with μo and h. With increasing oil viscosity and layer thickness, more capillary waves with small wavelengths are completely damped (columns 2, 4 in Fig. 4) and the cavity profile becomes smoother. The similar trend has also been reported by previous experimental studies, which argued that with increasing Oh, the capillary waves are progressively damped, resulting in a smaller and faster jet3,21,22.

Fig. 5: Capillary wave velocity.
figure5

Dependence of dimensionless velocity vd/vc of the selected dominant capillary wave on the dimensionless oil layer thickness h/R during bubble bursting at the oil-covered aqueous surface, where ({v}_{{{{{{mathrm{c}}}}}}}={left(frac{{gamma }_{{{{{{mathrm{e}}}}}}}}{{rho }_{{{{{{mathrm{w}}}}}}}R}right)}^{1/2}) is the inertial capillary velocity. Inset shows that vd is measured when the selected dominant wave goes through the position with an angle of θ = π/4 corresponding to the vertical cavity axis. Error bars are calculated as the standard deviations of data of at least 10 runs.

From the above observations on the cavity profile as well as the capillary wave propagation, the viscous damping of the capillary waves as well as the wavelength of the selected dominant wave is increased with the oil viscosity and layer thickness. Combining our argument on oil spreading at the cavity surface, we expect that the viscous attenuation and selection of the capillary waves are modified by the presence of a more viscous oil film on the bubble cavity surface, and the viscous damping rate increases with oil viscosity and layer thickness. Next, we will explore how to connect such damping on the jet ejection with the oil spreading.

Viscous damping with oil spreading

While Bo compares the gravity and capillary effects, Oh compares the viscous damping rate of the cavity collapse, ({t}_{{{{{{mathrm{d}}}}}}}^{-1}), and the inverse of the time of cavity collapse, ({t}_{{{{{{mathrm{c}}}}}}}^{-1})25,35. Our experimental observation shows that the capillary waves are progressively damped with the increase of the oil viscosity and layer thickness, indicating a higher viscous damping rate of cavity collapse. Here we derive the viscous damping rate with an oil-covered interface combining the oil spreading dynamics.

The thin oil film spreading along the cavity surface can be considered as a viscous surface film with two-dimensional shear viscosity μohe and dilatational viscosity 3μohe38, where he is the film thickness (see Fig. 6d and ‘Methods’ for the detailed derivation). Thus, for such a compound interface, we obtain a leading order approximation for the total dissipation rate of a capillary wave with a wavelength λ and wave number k ~ λ−1 as

$$langle Drangle =frac{4({mu }_{{{{{{mathrm{w}}}}}}}+{mu }_{{{{{{mathrm{o}}}}}}}k{h}_{{{{{{mathrm{e}}}}}}}){k}^{2}}{{rho }_{{{{{{mathrm{w}}}}}}}}{E}_{0}.$$

(5)

Fig. 6: Schematics of bubble bursting at an air–oil–water interface and scaling laws of jet tip radius and velocity.
figure6

a Cap rupture, b cavity collapse, and c jet formation of bubble bursting at an oil-covered aqueous surface. The oil spreading along the cavity surface has a flow rate of Q from the oil layer around the cavity with an initial thickness of hi. d Zoom-in view of the red square zone in (b), showing a capillary wave of wavelength λ at a water surface covered with an oil film of thickness he. Dimensionless (e) radius rj/R and (f) velocity vj/vc of the jet tip as a function of the revised Ohnesorge number Ohe. In (e) and (f), the solid lines represent the scaling laws of Eqs. (12) and (13), and the dashed lines represent the scaling laws of Eqs. (20) and (21), respectively. Error bars are calculated as the standard deviations of data of at least 10 runs.

Since the amplitude of capillary waves, α decreases exponentially in time by ({{{{{{{{rm{e}}}}}}}}}^{-t/{t}_{{{{{{mathrm{d}}}}}}lambda }})39, while ({E}_{0}propto {alpha }^{2}propto {{{{{{{{rm{e}}}}}}}}}^{-2t/{t}_{{{{{{mathrm{d}}}}}}lambda }}) with ({t}_{{{{{{mathrm{d}}}}}}lambda }^{-1}) as the effective damping rate of the capillary wave with a wavelength λ, we consider

$$frac{{{{{{{{rm{d}}}}}}}}{E}_{0}}{{{{{{{{rm{d}}}}}}}}t}=-langle Drangle .$$

(6)

Therefore, we obtain

$${t}_{{{{{{mathrm{d}}}}}}lambda }^{-1}=2frac{{mu }_{{{{{{mathrm{w}}}}}}}+{mu }_{{{{{{mathrm{o}}}}}}}k{h}_{{{{{{mathrm{e}}}}}}}}{{rho }_{{{{{{mathrm{w}}}}}}}}{k}^{2}.$$

(7)

We note that Eq. (7) also agrees with the expression for the capillary wave damping rate due to a viscous surface fluid layer by Jenkins and Jacobs36. Though there is a series of capillary waves with different λ propagating along the cavity surface, the only characteristic length of the initial condition of the system, R, is adopted in ({t}_{{{{{{mathrm{d}}}}}}}^{-1}) which characterizes the viscous damping of the cavity collapse25,35,40. Following this argument, by using k ~ R−1 in our experiment, we further obtain

$${t}_{{{{{{mathrm{d}}}}}}}^{-1} sim frac{{mu }_{{{{{{mathrm{w}}}}}}}+frac{{h}_{{{{{{mathrm{e}}}}}}}}{R}{mu }_{{{{{{mathrm{o}}}}}}}}{{rho }_{{{{{{mathrm{w}}}}}}}{R}^{2}}.$$

(8)

We observe that the oil film spreading along the cavity surface has a non-uniform thickness profile (Fig. 3b–d). For the sake of simplicity to reveal the driving physical mechanism, we approximate the average film thickness he with respect to the effective damping rate, which is assumed to be mainly contributed by the spreading of the macroscopic oil film considering the much smaller thickness of the precursor film in comparison. For an oil layer surrounding the bubble cavity, we consider the layer as an infinite reservoir localized at the cavity edge, which provides a flow rate Q to form the oil film on the bubble cavity. Q is estimated as (Q, sim ,2pi R{h}_{{{{{{mathrm{i}}}}}}}bar{v}), where hi is the initial oil layer thickness at the boundary of the bubble cavity before spreading (Fig. 6b), and (bar{v}) is the average inward spreading velocity of the macroscopic oil edge. Similar to the scenario for inward spreading of a healing capillary film41, the time evolution of hi scales with the initial oil layer thickness h, while (bar{v}) is estimated by γe/μo42,43. Therefore, Q ~ 2πRhγe/μo, and the average oil thickness he ~ Qtc/πR2, where tc is the time of cavity collapse as the capillary time (Eq. (3)). Now by scaling analysis, we obtain

$${h}_{{{{{{mathrm{e}}}}}}}, sim ,{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{o}}}}}}}^{-1}h,$$

(9)

where ({{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{o}}}}}}}={mu }_{{{{{{mathrm{o}}}}}}}/sqrt{{rho }_{{{{{{mathrm{o}}}}}}}{gamma }_{{{{{{mathrm{e}}}}}}}R}), showing that the oil film on the bubble cavity formed by inward spreading can be related to the initial oil layer thickness h by Oho. Given the simplified configuration (Fig. 6b, d) in this study, we revise Eq. (9) as ({h}_{{{{{{mathrm{e}}}}}}}, sim ,a{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{o}}}}}}}^{b}h), with a and b as the numerical factors obtained from experiments. Thus, the effective viscous damping rate of the cavity collapse is written as

$${t}_{{{{{{mathrm{d}}}}}}}^{-1} sim frac{{mu }_{{{{{{mathrm{w}}}}}}}+a{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{o}}}}}}}^{b}frac{h}{R}{mu }_{{{{{{mathrm{o}}}}}}}}{{rho }_{{{{{{mathrm{w}}}}}}}{R}^{2}}.$$

(10)

Scaling laws for the oily jetting

By modeling the dynamics of both bubble cavity collapse and oil spreading, we now propose scaling laws to predict rj and vj for the compound jetting. We note that Bo ≈ 0.4 was kept the same throughout all the experiments (Table 1). Meanwhile, the Oh can be revised adopting the effective viscous damping rate of the cavity collapse ({t}_{{{{{{mathrm{d}}}}}}}^{-1}) (Eq. (10)) for our experiments, yielding a revised Ohnesorge number as

$${{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{e}}}}}}}=frac{{t}_{{{{{{mathrm{d}}}}}}}^{-1}}{{t}_{{{{{{mathrm{c}}}}}}}^{-1}}=frac{{mu }_{{{{{{mathrm{w}}}}}}}+a{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{o}}}}}}}^{b}frac{h}{R}{mu }_{{{{{{mathrm{o}}}}}}}}{{({rho }_{{{{{{mathrm{w}}}}}}}{gamma }_{{{{{{mathrm{e}}}}}}}R)}^{1/2}}.$$

(11)

For bubble bursting at a clean liquid surface, rj decreases and vj increases monotonically with Oh when Oh < Ohc22,25,40, where Ohc ≈ 0.030537. Our experimental results show the same trends which means Ohe < Ohc (Fig. 2e, f). By balancing the viscous damping rate of the capillary wave ({t}_{{{{{{mathrm{d}}}}}}lambda }^{-1}) calculated using Eq. (7) with ({t}_{{{{{{mathrm{c}}}}}}}^{-1}), the wavelength of the selected dominant wave can be obtained as ({lambda }_{{{{{{mathrm{d}}}}}}}/Rpropto {{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{e}}}}}}}^{1/2}), similar to the argument for bubble bursting at a clean liquid surface with Oh < Ohc25. It was suggested that λd sets the radius at the base of the truncated cone-shaped cavity at the onset of jet formation, which further determines the radius of the jet tip, yielding ({r}_{{{{{{mathrm{j}}}}}}}/R={c}_{r}(1-{({{{{{mathrm{Oh}}}}}}/{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{c}}}}}}})}^{1/2})) with Oh < Ohc37. Therefore, with the revised Ohnesorge number Ohe, we propose that

$$frac{{r}_{{{{{{mathrm{j}}}}}}}}{R}={c}_{r}left(1-{left(frac{{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{e}}}}}}}}{{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{c}}}}}}}}right)}^{1/2}right),,{{mbox{for}}},{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{e}}}}}}} , < , {{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{c}}}}}}}{{mbox{}}},$$

(12)

where cr = 0.2215 as predicted by the prior work37. For bubble bursting at a clean liquid surface, prior work also argued that vj can be calculated as the flow generated by a continuous line of sinks extending along the axis of symmetry a distance proportional to λd37. Based on this argument, we further propose that

$$frac{{v}_{{{{{{mathrm{j}}}}}}}}{{v}_{{{{{{mathrm{c}}}}}}}}=frac{{c}_{v}}{{(-{{mbox{ln}}}({r}_{{{{{{mathrm{j}}}}}}}/R))}^{1/2}}left(frac{1}{{r}_{{{{{{mathrm{j}}}}}}}/R}-frac{1}{{r}_{{{{{{mathrm{j}}}}}}}/R+4.67{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{e}}}}}}}^{1/2}}right),{{mbox{for}}},{{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{e}}}}}}} , < , {{{{{mathrm{O}}}}}}{{{{{{mathrm{h}}}}}}}_{{{{{{mathrm{c}}}}}}}{{mbox{}}},$$

(13)

where rj/R is calculated by Eq. (12), and cv is found to be ≈1.5. The smaller cv compared to the literature value of 4.237 may be attributed to the deceleration of the jet tip when it rises from the bubble nadir to the surface37 and the effect of relatively large Bo40 in the current experiments.

For a wide range of experimental conditions, including viscosity of 5–1000 cSt and layer thickness of 0.67–2 mm, we find that Eqs. (12) and (13) agree well with our experimental results as shown in Fig. 6e, f. Here, Ohe takes into account the additional viscous dissipation by the oil layer film on the cavity surface formed by spontaneous spreading, related to the oil viscosity and initial layer thickness. We note that a = 0.015 and b = −0.8 in Eq. (11) obtained by experimental fitting, indicating that the average oil-film thickness he = O(1 − 102 μm) R, are consistent with the experimental observations and the assumption for the oil film to be considered as a thin surface film. In addition, the fitting value of b is close to −1 obtained by the scaling analysis for Eq. (9). Meanwhile, we found that using the same a and b, the Ohe can also be adopted in the scaling laws proposed by other studies to fairly describe our experimental results29,35 (see Fig. 6e, f and ‘Methods’ for the detailed information). Overall, the proposed revised Ohnesorge number and scaling laws universally capture the jet dynamics of bubble bursting at an oil-covered aqueous surface in the current experimental range.



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Travel baron’s tip on when we’ll be jetting off again


International travel is expected to return within months, as Qantas restarts long-haul flights and pressure builds on the Government to fast-track the rollout of Australia’s COVID-19 vaccine.

Two of Australia’s largest travel organisations this week offered new hope to travel-hungry Australians, with Qantas selling seats to the US and UK from July, and Flight Centre ready to follow.

Australia’s national carrier restarted sales of the international flights despite both countries struggling to bring the virus under control.

“We continue to review and update our international schedule in response to the developing COVID-19 situation,” the airline said.

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

 

“Recently we have aligned the selling of our international services to reflect our expectation that international travel will begin to restart from July 2021.”

Flight Centre CEO Graham “Skroo” Turner told The Courier-Mail the Queensland travel giant would closely watch Qantas’ success before deciding whether to restart sales of its own international holiday packages.

Mr Turner said international travel was likely to return from July following Australia’s first COVID-19 vaccinations – which the Government hopes will start in March.

“I think it’s reasonable to accept that vaccinated people will be able to travel reasonably widely by July,” Mr Turner said.

“I would be surprised if a reasonable level of international travel for Australians wasn’t occurring by then.”

Mr Turner, who is locked in hotel quarantine following a business trip to London over Christmas, tipped British residents would be travelling across Europe within months despite the nation being plunged into its third national lockdown this week.

“They’ll be travelling by summer because the vaccine is being rolled out so that’s a positive,” he said.

 

 

Mr Turner expected Australia, which has led the world in managing the virus, would bounce back quickly once the vaccine was widely available.

The pace of the rollout, however, has been criticised by Opposition Leader Anthony Albanese, with more than 2.8 million Americans and 900,000 British people already receiving jabs.

Australia’s Pfizer vaccine is expected to be approved by the Therapeutic Goods Administration this month, however Chief Medical Officer Paul Kelly said further approvals and stock would be secured before widespread inoculation.

Meanwhile, growing clusters in New South Wales and Victoria has again raised concerns about Queensland’s jittery border.

Tourism leaders are calling for the state government to publicly outline clear triggers that will affect border changes instead of relying on confidential advice from the chief health officer.

Queensland Tourism Industry Council CEO Daniel Gschwind said the possibility of snap border closures as interstate clusters grew was “freaking everybody out”.

“Any system that provides greater certainty would certainly be helpful, so we have a bit more predictability on what will happen if a case is identified or a cluster emerges,” he said.

“If we can avoid wholesale border closures, that’s the aim of the game.

“That’s what’s really freaking everybody out and introducing enormous uncertainty into the market and then in consumers’ heads.”

 

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

 

Mr Turner also revealed Flight Centre lawyers are yet to receive a response to a right to information application seeking the medical advice underpinning Queensland’s border closures earlier this year.

The application, lodged on June 9, sought the documents revealing the heath advice relied on by Chief Health Officer Jeannette Young to justify closing the borders to Sydney and Melbourne between July and December.

Acting Health Minister Mark Furner said the Government would continue to make decisions based on expert health advice.

“It’s because of Queensland’s strong health response and our minimal restrictions that so many Queenslanders are enjoying all that Queensland has to offer over the Christmas-New Year period,” he said.

 

 

 

 

 

Originally published as Travel baron’s tip on when we’ll be jetting off again





Source link

Travel baron’s tip on when we’ll be jetting off again


International travel is expected to return within months, as Qantas restarts long-haul flights and pressure builds on the Government to fast-track the rollout of Australia’s COVID-19 vaccine.

Two of Australia’s largest travel organisations this week offered new hope to travel-hungry Australians, with Qantas selling seats to the US and UK from July, and Flight Centre ready to follow.

Australia’s national carrier restarted sales of the international flights despite both countries struggling to bring the virus under control.

“We continue to review and update our international schedule in response to the developing COVID-19 situation,” the airline said.

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

 

“Recently we have aligned the selling of our international services to reflect our expectation that international travel will begin to restart from July 2021.”

Flight Centre CEO Graham “Skroo” Turner told The Courier-Mail the Queensland travel giant would closely watch Qantas’ success before deciding whether to restart sales of its own international holiday packages.

Mr Turner said international travel was likely to return from July following Australia’s first COVID-19 vaccinations – which the Government hopes will start in March.

“I think it’s reasonable to accept that vaccinated people will be able to travel reasonably widely by July,” Mr Turner said.

“I would be surprised if a reasonable level of international travel for Australians wasn’t occurring by then.”

Mr Turner, who is locked in hotel quarantine following a business trip to London over Christmas, tipped British residents would be travelling across Europe within months despite the nation being plunged into its third national lockdown this week.

“They’ll be travelling by summer because the vaccine is being rolled out so that’s a positive,” he said.

 

 

Mr Turner expected Australia, which has led the world in managing the virus, would bounce back quickly once the vaccine was widely available.

The pace of the rollout, however, has been criticised by Opposition Leader Anthony Albanese, with more than 2.8 million Americans and 900,000 British people already receiving jabs.

Australia’s Pfizer vaccine is expected to be approved by the Therapeutic Goods Administration this month, however Chief Medical Officer Paul Kelly said further approvals and stock would be secured before widespread inoculation.

Meanwhile, growing clusters in New South Wales and Victoria has again raised concerns about Queensland’s jittery border.

Tourism leaders are calling for the state government to publicly outline clear triggers that will affect border changes instead of relying on confidential advice from the chief health officer.

Queensland Tourism Industry Council CEO Daniel Gschwind said the possibility of snap border closures as interstate clusters grew was “freaking everybody out”.

“Any system that provides greater certainty would certainly be helpful, so we have a bit more predictability on what will happen if a case is identified or a cluster emerges,” he said.

“If we can avoid wholesale border closures, that’s the aim of the game.

“That’s what’s really freaking everybody out and introducing enormous uncertainty into the market and then in consumers’ heads.”

 

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

 

Mr Turner also revealed Flight Centre lawyers are yet to receive a response to a right to information application seeking the medical advice underpinning Queensland’s border closures earlier this year.

The application, lodged on June 9, sought the documents revealing the heath advice relied on by Chief Health Officer Jeannette Young to justify closing the borders to Sydney and Melbourne between July and December.

Acting Health Minister Mark Furner said the Government would continue to make decisions based on expert health advice.

“It’s because of Queensland’s strong health response and our minimal restrictions that so many Queenslanders are enjoying all that Queensland has to offer over the Christmas-New Year period,” he said.

 

 

 

 

 

Originally published as Travel baron’s tip on when we’ll be jetting off again





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Travel baron’s tip on when we’ll be jetting off again


International travel is expected to return within months, as Qantas restarts long-haul flights and pressure builds on the Government to fast-track the rollout of Australia’s COVID-19 vaccine.

Two of Australia’s largest travel organisations this week offered new hope to travel-hungry Australians, with Qantas selling seats to the US and UK from July, and Flight Centre ready to follow.

Australia’s national carrier restarted sales of the international flights despite both countries struggling to bring the virus under control.

“We continue to review and update our international schedule in response to the developing COVID-19 situation,” the airline said.

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

 

“Recently we have aligned the selling of our international services to reflect our expectation that international travel will begin to restart from July 2021.”

Flight Centre CEO Graham “Skroo” Turner told The Courier-Mail the Queensland travel giant would closely watch Qantas’ success before deciding whether to restart sales of its own international holiday packages.

Mr Turner said international travel was likely to return from July following Australia’s first COVID-19 vaccinations – which the Government hopes will start in March.

“I think it’s reasonable to accept that vaccinated people will be able to travel reasonably widely by July,” Mr Turner said.

“I would be surprised if a reasonable level of international travel for Australians wasn’t occurring by then.”

Mr Turner, who is locked in hotel quarantine following a business trip to London over Christmas, tipped British residents would be travelling across Europe within months despite the nation being plunged into its third national lockdown this week.

“They’ll be travelling by summer because the vaccine is being rolled out so that’s a positive,” he said.

 

 

Mr Turner expected Australia, which has led the world in managing the virus, would bounce back quickly once the vaccine was widely available.

The pace of the rollout, however, has been criticised by Opposition Leader Anthony Albanese, with more than 2.8 million Americans and 900,000 British people already receiving jabs.

Australia’s Pfizer vaccine is expected to be approved by the Therapeutic Goods Administration this month, however Chief Medical Officer Paul Kelly said further approvals and stock would be secured before widespread inoculation.

Meanwhile, growing clusters in New South Wales and Victoria has again raised concerns about Queensland’s jittery border.

Tourism leaders are calling for the state government to publicly outline clear triggers that will affect border changes instead of relying on confidential advice from the chief health officer.

Queensland Tourism Industry Council CEO Daniel Gschwind said the possibility of snap border closures as interstate clusters grew was “freaking everybody out”.

“Any system that provides greater certainty would certainly be helpful, so we have a bit more predictability on what will happen if a case is identified or a cluster emerges,” he said.

“If we can avoid wholesale border closures, that’s the aim of the game.

“That’s what’s really freaking everybody out and introducing enormous uncertainty into the market and then in consumers’ heads.”

 

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

 

Mr Turner also revealed Flight Centre lawyers are yet to receive a response to a right to information application seeking the medical advice underpinning Queensland’s border closures earlier this year.

The application, lodged on June 9, sought the documents revealing the heath advice relied on by Chief Health Officer Jeannette Young to justify closing the borders to Sydney and Melbourne between July and December.

Acting Health Minister Mark Furner said the Government would continue to make decisions based on expert health advice.

“It’s because of Queensland’s strong health response and our minimal restrictions that so many Queenslanders are enjoying all that Queensland has to offer over the Christmas-New Year period,” he said.

 

 

 

 

 

Originally published as Travel baron’s tip on when we’ll be jetting off again





Source link

Travel baron’s tip on when we’ll be jetting off again


International travel is expected to return within months, as Qantas restarts long-haul flights and pressure builds on the Government to fast-track the rollout of Australia’s COVID-19 vaccine.

Two of Australia’s largest travel organisations this week offered new hope to travel-hungry Australians, with Qantas selling seats to the US and UK from July, and Flight Centre ready to follow.

Australia’s national carrier restarted sales of the international flights despite both countries struggling to bring the virus under control.

“We continue to review and update our international schedule in response to the developing COVID-19 situation,” the airline said.

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

 

“Recently we have aligned the selling of our international services to reflect our expectation that international travel will begin to restart from July 2021.”

Flight Centre CEO Graham “Skroo” Turner told The Courier-Mail the Queensland travel giant would closely watch Qantas’ success before deciding whether to restart sales of its own international holiday packages.

Mr Turner said international travel was likely to return from July following Australia’s first COVID-19 vaccinations – which the Government hopes will start in March.

“I think it’s reasonable to accept that vaccinated people will be able to travel reasonably widely by July,” Mr Turner said.

“I would be surprised if a reasonable level of international travel for Australians wasn’t occurring by then.”

Mr Turner, who is locked in hotel quarantine following a business trip to London over Christmas, tipped British residents would be travelling across Europe within months despite the nation being plunged into its third national lockdown this week.

“They’ll be travelling by summer because the vaccine is being rolled out so that’s a positive,” he said.

 

 

Mr Turner expected Australia, which has led the world in managing the virus, would bounce back quickly once the vaccine was widely available.

The pace of the rollout, however, has been criticised by Opposition Leader Anthony Albanese, with more than 2.8 million Americans and 900,000 British people already receiving jabs.

Australia’s Pfizer vaccine is expected to be approved by the Therapeutic Goods Administration this month, however Chief Medical Officer Paul Kelly said further approvals and stock would be secured before widespread inoculation.

Meanwhile, growing clusters in New South Wales and Victoria has again raised concerns about Queensland’s jittery border.

Tourism leaders are calling for the state government to publicly outline clear triggers that will affect border changes instead of relying on confidential advice from the chief health officer.

Queensland Tourism Industry Council CEO Daniel Gschwind said the possibility of snap border closures as interstate clusters grew was “freaking everybody out”.

“Any system that provides greater certainty would certainly be helpful, so we have a bit more predictability on what will happen if a case is identified or a cluster emerges,” he said.

“If we can avoid wholesale border closures, that’s the aim of the game.

“That’s what’s really freaking everybody out and introducing enormous uncertainty into the market and then in consumers’ heads.”

 

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

 

Mr Turner also revealed Flight Centre lawyers are yet to receive a response to a right to information application seeking the medical advice underpinning Queensland’s border closures earlier this year.

The application, lodged on June 9, sought the documents revealing the heath advice relied on by Chief Health Officer Jeannette Young to justify closing the borders to Sydney and Melbourne between July and December.

Acting Health Minister Mark Furner said the Government would continue to make decisions based on expert health advice.

“It’s because of Queensland’s strong health response and our minimal restrictions that so many Queenslanders are enjoying all that Queensland has to offer over the Christmas-New Year period,” he said.

 

 

 

 

 

Originally published as Travel baron’s tip on when we’ll be jetting off again





Source link

Travel baron’s tip on when we’ll be jetting off again


International travel is expected to return within months, as Qantas restarts long-haul flights and pressure builds on the Government to fast-track the rollout of Australia’s COVID-19 vaccine.

Two of Australia’s largest travel organisations this week offered new hope to travel-hungry Australians, with Qantas selling seats to the US and UK from July, and Flight Centre ready to follow.

Australia’s national carrier restarted sales of the international flights despite both countries struggling to bring the virus under control.

“We continue to review and update our international schedule in response to the developing COVID-19 situation,” the airline said.

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

 

“Recently we have aligned the selling of our international services to reflect our expectation that international travel will begin to restart from July 2021.”

Flight Centre CEO Graham “Skroo” Turner told The Courier-Mail the Queensland travel giant would closely watch Qantas’ success before deciding whether to restart sales of its own international holiday packages.

Mr Turner said international travel was likely to return from July following Australia’s first COVID-19 vaccinations – which the Government hopes will start in March.

“I think it’s reasonable to accept that vaccinated people will be able to travel reasonably widely by July,” Mr Turner said.

“I would be surprised if a reasonable level of international travel for Australians wasn’t occurring by then.”

Mr Turner, who is locked in hotel quarantine following a business trip to London over Christmas, tipped British residents would be travelling across Europe within months despite the nation being plunged into its third national lockdown this week.

“They’ll be travelling by summer because the vaccine is being rolled out so that’s a positive,” he said.

 

 

Mr Turner expected Australia, which has led the world in managing the virus, would bounce back quickly once the vaccine was widely available.

The pace of the rollout, however, has been criticised by Opposition Leader Anthony Albanese, with more than 2.8 million Americans and 900,000 British people already receiving jabs.

Australia’s Pfizer vaccine is expected to be approved by the Therapeutic Goods Administration this month, however Chief Medical Officer Paul Kelly said further approvals and stock would be secured before widespread inoculation.

Meanwhile, growing clusters in New South Wales and Victoria has again raised concerns about Queensland’s jittery border.

Tourism leaders are calling for the state government to publicly outline clear triggers that will affect border changes instead of relying on confidential advice from the chief health officer.

Queensland Tourism Industry Council CEO Daniel Gschwind said the possibility of snap border closures as interstate clusters grew was “freaking everybody out”.

“Any system that provides greater certainty would certainly be helpful, so we have a bit more predictability on what will happen if a case is identified or a cluster emerges,” he said.

“If we can avoid wholesale border closures, that’s the aim of the game.

“That’s what’s really freaking everybody out and introducing enormous uncertainty into the market and then in consumers’ heads.”

 

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

 

Mr Turner also revealed Flight Centre lawyers are yet to receive a response to a right to information application seeking the medical advice underpinning Queensland’s border closures earlier this year.

The application, lodged on June 9, sought the documents revealing the heath advice relied on by Chief Health Officer Jeannette Young to justify closing the borders to Sydney and Melbourne between July and December.

Acting Health Minister Mark Furner said the Government would continue to make decisions based on expert health advice.

“It’s because of Queensland’s strong health response and our minimal restrictions that so many Queenslanders are enjoying all that Queensland has to offer over the Christmas-New Year period,” he said.

 

 

 

 

 

Originally published as Travel baron’s tip on when we’ll be jetting off again





Source link

Travel baron’s tip on when we’ll be jetting off again


International travel is expected to return within months, as Qantas restarts long-haul flights and pressure builds on the Government to fast-track the rollout of Australia’s COVID-19 vaccine.

Two of Australia’s largest travel organisations this week offered new hope to travel-hungry Australians, with Qantas selling seats to the US and UK from July, and Flight Centre ready to follow.

Australia’s national carrier restarted sales of the international flights despite both countries struggling to bring the virus under control.

“We continue to review and update our international schedule in response to the developing COVID-19 situation,” the airline said.

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

 

“Recently we have aligned the selling of our international services to reflect our expectation that international travel will begin to restart from July 2021.”

Flight Centre CEO Graham “Skroo” Turner told The Courier-Mail the Queensland travel giant would closely watch Qantas’ success before deciding whether to restart sales of its own international holiday packages.

Mr Turner said international travel was likely to return from July following Australia’s first COVID-19 vaccinations – which the Government hopes will start in March.

“I think it’s reasonable to accept that vaccinated people will be able to travel reasonably widely by July,” Mr Turner said.

“I would be surprised if a reasonable level of international travel for Australians wasn’t occurring by then.”

Mr Turner, who is locked in hotel quarantine following a business trip to London over Christmas, tipped British residents would be travelling across Europe within months despite the nation being plunged into its third national lockdown this week.

“They’ll be travelling by summer because the vaccine is being rolled out so that’s a positive,” he said.

 

 

Mr Turner expected Australia, which has led the world in managing the virus, would bounce back quickly once the vaccine was widely available.

The pace of the rollout, however, has been criticised by Opposition Leader Anthony Albanese, with more than 2.8 million Americans and 900,000 British people already receiving jabs.

Australia’s Pfizer vaccine is expected to be approved by the Therapeutic Goods Administration this month, however Chief Medical Officer Paul Kelly said further approvals and stock would be secured before widespread inoculation.

Meanwhile, growing clusters in New South Wales and Victoria has again raised concerns about Queensland’s jittery border.

Tourism leaders are calling for the state government to publicly outline clear triggers that will affect border changes instead of relying on confidential advice from the chief health officer.

Queensland Tourism Industry Council CEO Daniel Gschwind said the possibility of snap border closures as interstate clusters grew was “freaking everybody out”.

“Any system that provides greater certainty would certainly be helpful, so we have a bit more predictability on what will happen if a case is identified or a cluster emerges,” he said.

“If we can avoid wholesale border closures, that’s the aim of the game.

“That’s what’s really freaking everybody out and introducing enormous uncertainty into the market and then in consumers’ heads.”

 

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

 

Mr Turner also revealed Flight Centre lawyers are yet to receive a response to a right to information application seeking the medical advice underpinning Queensland’s border closures earlier this year.

The application, lodged on June 9, sought the documents revealing the heath advice relied on by Chief Health Officer Jeannette Young to justify closing the borders to Sydney and Melbourne between July and December.

Acting Health Minister Mark Furner said the Government would continue to make decisions based on expert health advice.

“It’s because of Queensland’s strong health response and our minimal restrictions that so many Queenslanders are enjoying all that Queensland has to offer over the Christmas-New Year period,” he said.

 

 

 

 

 

Originally published as Travel baron’s tip on when we’ll be jetting off again





Source link

Travel baron’s tip on when we’ll be jetting off again


International travel is expected to return within months, as Qantas restarts long-haul flights and pressure builds on the Government to fast-track the rollout of Australia’s COVID-19 vaccine.

Two of Australia’s largest travel organisations this week offered new hope to travel-hungry Australians, with Qantas selling seats to the US and UK from July, and Flight Centre ready to follow.

Australia’s national carrier restarted sales of the international flights despite both countries struggling to bring the virus under control.

“We continue to review and update our international schedule in response to the developing COVID-19 situation,” the airline said.

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

Brisbane-based Flight Centre CEO Graham “Skroo” Turner

 

“Recently we have aligned the selling of our international services to reflect our expectation that international travel will begin to restart from July 2021.”

Flight Centre CEO Graham “Skroo” Turner told The Courier-Mail the Queensland travel giant would closely watch Qantas’ success before deciding whether to restart sales of its own international holiday packages.

Mr Turner said international travel was likely to return from July following Australia’s first COVID-19 vaccinations – which the Government hopes will start in March.

“I think it’s reasonable to accept that vaccinated people will be able to travel reasonably widely by July,” Mr Turner said.

“I would be surprised if a reasonable level of international travel for Australians wasn’t occurring by then.”

Mr Turner, who is locked in hotel quarantine following a business trip to London over Christmas, tipped British residents would be travelling across Europe within months despite the nation being plunged into its third national lockdown this week.

“They’ll be travelling by summer because the vaccine is being rolled out so that’s a positive,” he said.

 

 

Mr Turner expected Australia, which has led the world in managing the virus, would bounce back quickly once the vaccine was widely available.

The pace of the rollout, however, has been criticised by Opposition Leader Anthony Albanese, with more than 2.8 million Americans and 900,000 British people already receiving jabs.

Australia’s Pfizer vaccine is expected to be approved by the Therapeutic Goods Administration this month, however Chief Medical Officer Paul Kelly said further approvals and stock would be secured before widespread inoculation.

Meanwhile, growing clusters in New South Wales and Victoria has again raised concerns about Queensland’s jittery border.

Tourism leaders are calling for the state government to publicly outline clear triggers that will affect border changes instead of relying on confidential advice from the chief health officer.

Queensland Tourism Industry Council CEO Daniel Gschwind said the possibility of snap border closures as interstate clusters grew was “freaking everybody out”.

“Any system that provides greater certainty would certainly be helpful, so we have a bit more predictability on what will happen if a case is identified or a cluster emerges,” he said.

“If we can avoid wholesale border closures, that’s the aim of the game.

“That’s what’s really freaking everybody out and introducing enormous uncertainty into the market and then in consumers’ heads.”

 

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

Queensland Tourism Industry Council CEO Daniel Gschwind with Premier Annastacia Palaszczuk

 

Mr Turner also revealed Flight Centre lawyers are yet to receive a response to a right to information application seeking the medical advice underpinning Queensland’s border closures earlier this year.

The application, lodged on June 9, sought the documents revealing the heath advice relied on by Chief Health Officer Jeannette Young to justify closing the borders to Sydney and Melbourne between July and December.

Acting Health Minister Mark Furner said the Government would continue to make decisions based on expert health advice.

“It’s because of Queensland’s strong health response and our minimal restrictions that so many Queenslanders are enjoying all that Queensland has to offer over the Christmas-New Year period,” he said.

 

 

 

 

 

Originally published as Travel baron’s tip on when we’ll be jetting off again





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