Water Droplets In Air Research Articles

Scale-Resolving Simulation of Shock-Induced Aerobreakup of Water Droplet

Two different scale-resolving simulation (SRS) approaches to turbulence modeling and simulation are used to predict the breakup of a spherical water droplet in air, due to the impact of a traveling plane shock wave. The compressible flow governing equations are solved by means of a finite volume-based numerical method, with the volume-of-fluid technique being employed to track the air–water interface on the dynamically adaptive mesh. The three-dimensional analysis is performed in the shear stripping regime, examining the drift, deformation, and breakup of the droplet for a benchmark flow configuration. The comparison of the present SRS results against reference experimental and numerical data, in terms of both droplet morphology and breakup dynamics, provides evidence that the adopted computational methods have significant practical potential, being able to locally reproduce unsteady small-scale flow structures. These computational models offer viable alternatives to higher-fidelity, more costly methods for engineering simulations of complex two-phase turbulent compressible flows.

Simple fabrication of anisotropic slippery lubricant-infused surface for directional transportation and anti-corrosion by metal-metal laminated composites

Slippery lubricant-infused surfaces with anisotropy for directional transportation have been widely researched and fabricated. However, the preparation of the required surface morphology remains complex and challenging. Inspired by the laminated structure found on natural shell nacre and slippery characteristics of nepenthes, a simple and universal method was provided to fabricate anisotropic slippery lubricant-infused surface. 304/TC4 metal-metal laminated composites were prepared by diffusion bonding 304 stainless steel and TC4 titanium alloy foils. A regular micro array with grooves was obtained through simple chemical etching. The widths of grooves and bulges, as well as the depths of grooves could be adjusted as needed. After the chemical modification, the lubricant was infused into grooves to obtain anisotropic slippery lubricant-infused surfaces. The directional transportations along the grooves of water droplet in air and bubbles underwater were achieved on the fabricated surfaces. Furthermore, the achieved surfaces demonstrated outstanding performance in anti-corrosion and anti-fouling. A noteworthy advantage of using laminated composites to fabricate anisotropic slippery lubricant-infused surfaces lies in its simplicity, universality, and repeatability. Based on the previous reports about laminated composites, the structure with grooves can been obtained by simple chemical etching. This method is suitable for various materials, including metal, ceramic, carbon material, and polymers. It has great potential application in water collection, directional transportations, anti-corrosion and anti-fouling.

Liquid-Assisted Bionic Conical Needle for In-Air and In-Oil-Water Droplet Ultrafast Unidirectional Transportation and Efficient Fog Harvesting.

Learning from nature, many bionic materials and surfaces have been developed for the directional transportation of water and fog collection. However, current research mainly focuses on the self-transportation behavior of droplets in air-phase environments, rarely concerning underoil environments. Herein, in this work, a liquid-assisted bionic copper needle was fabricated for the rapid self-transportation of water droplets in air and oil environments. The water droplet can be spontaneously transported on the as-prepared bionic copper needle from the tip to the base. More importantly, the water-prewetted bionic copper needle can achieve the ultrafast unidirectional transportation of a water droplet in an oil environment, showing a maximum transport velocity of 76.2 mm/s and a transport distance over 33 mm, which were ten times higher than those reported in the previous research. Additionally, the droplet transport mechanism was revealed. The effects of the apex angle and tilt angle of the as-prepared bionic needle and droplet volume on the self-transportation behavior of water droplets were systematically investigated. The results indicated that the transport velocity of the water droplet decreased with the increase of the apex angle of the conical needle, while it increased with the increase of the droplet volume and needle tilt angle. Furthermore, the as-prepared bionic copper needle exhibited excellent fog collection performance with a single copper needle fog collecting efficiency of up to 2220 mg/h, which was 9.7 times that of the original copper needle. In summary, this work provides a simple and novel method to fabricate bionic copper needles for the directional self-transportation of water droplets in air-phase and oil-phase environments as well as efficient fog collection. It shows great application potential in the fields of microfluidics, desalination, and freshwater collection.

Acoustic attenuation in mixtures of air and water droplets

Sound propagation through mixtures of air and water-droplets occurs in many natural systems such as in fogs and clouds, where it has been observed that acoustic waves are attenuated to a greater degree than in the absence of water droplets. This effect has been exploited at space shuttle launches with the sound suppression system, where water sprayed around the shuttle significantly reduces the acoustic power radiated from the rocket engines. Theoretical studies have investigated various mechanisms causing acoustic attenuation in air-water droplet mixtures: heat transfer, mass transfer and momentum transfer. More recent studies have incorporated other mechanisms into analytical models so that they are more representative of sound propagation through fogs or clouds. The aim of this paper is to review the different mechanisms causing attenuation of acoustic waves, and to present a comparison of the different analytical models to illustrate the differences in predicted acoustic attenuation and dispersion. Some limitations of the different models are identified, and proposals for experimental work to validate analytical results are discussed.

Collision Statistics of Droplets in Turbulence Considering Lubrication Interactions, Mobility of Interfaces, and Non-continuum Molecular Effects

Collision statistics of same-size aerodynamically interacting droplets in homogeneous isotropic turbulence is examined via hybrid direct numerical simulations combined with Lagrangian particle tracking under a point-particle assumption and a one-way momentum coupling. The simulations are performed both in the absence and presence of gravity for various droplet Stokes numbers (0.1–2) over a wide range of liquid water contents (LWCs = 1–30 g/m3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ ext {g/m}^3$$\\end{document}). Also, the effects of using different representations of the lubrication forces, i.e. a continuum and a non-continuum one, have been investigated. The results have highlighted the importance of considering the aerodynamic interaction, especially in the presence of gravity for the systems that have high LWCs. Likewise, taking the lubrication force into account shows a notable change in statistics, but a non-continuum representation yields results that are close to the continuum one. In addition, the impact of modeling droplets as fluid drops instead of rigid particles has been examined. Obtaining quite close statistics under both cases demonstrates that a rigid particle assumption for water droplets in air is sufficiently accurate owing to the high water-to-air viscosity ratio. Moreover, the collision efficiency is shown to be in the range 60–100% in the absence of gravity, which approaches 100% as the LWC is enlarged. In the presence of gravity, however, the efficiency grows, with both the Stokes number and the LWC, to values as high as 300%. Finally, for settling droplet systems, the enhancement factor due to turbulence is quantified, exhibiting a growth with the LWC and a reduction with the Stokes number.

Numerical Analysis of the Free-Falling Process of a Water Droplet at Different Temperatures

The collision behavior and ice formation of a water droplet are affected by its falling process. In this paper, the two-phase flow of air and a water droplet at a specific temperature is adopted to investigate the processes of falling and freezing of a single water droplet. To track the air–water droplet interface and the temperature distribution, the level-set method and the non-isothermal flow coupling method are used, and the freezing model is added into the water’s control equations. The numerical results indicated that with the initial temperature at 283.15 K and the spherical shape, the water droplet changes to the shape of a straw hat at 293.15 K and a drum at 293.15 K but an oval face in freezing temperatures at 0.10 s. There is an obvious drop in the downward velocity when the water droplet falls in mild temperatures at 0.09 s. The downward velocity of the water droplet in air at sub-zero temperatures has a continuous increase during the time span from 0 s to 0.10 s. There is also an obvious difference when the water droplet impinges on the solid bottom. Lastly, the freezing of sessile water droplets attached on the horizontal surface is helpful to reveal the unique phase change process of water droplets in cold air.

Water droplet evaporation in atmospheric air stream

Evaporation of a water droplet in air is a natural phenomenon that causes the droplet and air properties to change over time. In this paper, time-dependent variation of air and water droplet properties in a flow is examined with the developed numerical model, in the range of conditions that concern air-conditioning and respiratory-based medical events and applications. An experimental setup is built and the model is validated with experiments carried out for 27 cases. Input parameters are chosen as the inlet air temperature, relative humidity, droplet temperature and diameter, and air–water mass mixing ratio. Output properties are determined as the outlet air temperature, relative humidity, mass droplet ratio, and droplet temperature to define the application case in the simplest way. Model results of 432 different cases are used to develop correlations with R20 values above 0.984, to present the effects of co-variation of input parameters. The results show that the latent heat demand of droplet evaporation is the main factor in the decrease of air temperature, while droplet temperature has almost no effect. As the air becomes saturated with moisture, evaporation almost stops and droplets carried by air flow remain. The droplet diameter affects only the process speed by reducing the processing time by the square of the reduction ratio. The developed numerical model and correlations allow the rapid determination of properties change in air–water stream over time, so it will provide great convenience to researchers dealing with water droplet evaporation in an atmospheric air stream.

Hydrophobicity/Oleophilicity of Autoclaved Aerated Concrete (AAC) Grains Coated with Oleic and Stearic Acids for Application as Oil/Water Separating Filtration and Adsorbent Materials in Vietnam

Separation of oil and water is an effective technique to treat oily wastewater. For examining the applicability of porous grains coated with hydrophobic agents (HA) as low-cost and easily available filtration and adsorbent materials in the separation of oil and water, this study assessed the hydrophobicity/oleophilicity of porous grains made from autoclaved aerated concrete scrap coated with low-cost and harmless hydrophobic agents such as oleic and stearic acids. Tests using a sessile droplet method showed unique relationships between the contact angles (CA) of water droplets in air (CAwa), oil droplets in water (CAow) and coated HA concentrations. The CAwa increased linearly with increasing HA concentration and then became almost constant and/or gently increased after a specific point, indicating that a minimum coating amount gives the maximum hydrophobicity to HA-coated porous grains exists. The CAow gradually decreased exponentially with increasing HA concentration. In particular, the CAow of porous grains coated with stearic acid decreased with increasing of HA concentration in a two-step process. Furthermore, analyses of the Pearson correlation showed that both CAwa and CAow correlated well with the specific surface area (SSA), implying that the SSA is a good indicator as a quick assessment of hydrophobicity/oleophilicity of HA-coated porous grains.

A semi implicit compressible solver for two-phase flows of real fluids

The development of numerical solvers able to simulate compressible two-phase flows is still a great challenge in computational fluid dynamics. The interaction between acoustic waves and interfaces is of major concern for several engineering and biomedical applications, among which atomization in combustion chambers, cavitation problems, underwater explosions and bubble shock interactions. For instance, there are experimental evidences that acoustic waves can have an important effect on the atomization process, and this could have a great impact on combustion. However, usual approaches for DNS of primary atomization are based on incompressible solvers and therefore are not able to capture the propagation of acoustic waves and therefore cannot be used to simulate such phenomena. The numerical problem associated with the simulation of compressible two-phase flows is challenging, mostly because of the huge spatial variations of the speed of sound and the corresponding low Mach number in the liquid phase. In the present work, a numerical solver able to study subsonic compressible two-phase flows is presented. The solver is based on a complete formulation of the Navier-Stokes equations with real fluid equations of state, which are solved with a semi-implicit projection method. It is shown that the solver can handle a large range of compressible subsonic flows, both for a single phase or for two phases, as the flow induced by free convection, a bubble expansion in isothermal or isentropic conditions, and interaction between acoustic waves and liquid-gas interfaces. Eventually, attention will be given to the simulation of a water droplet in air, under the excitation of a stationary acoustic wave. It is also shown that the solver exhibits equivalent performances as an incompressible solver in configurations where compressible effects have no effects.

Facile and scalable surface functionalization approach with small silane molecules for oil/water separation and demulsification of surfactant/asphaltenes-stabilized emulsions

Oil contaminations have been challenging issues in a wide range of engineering and environmental fields. Herein, we employ a small silane molecule, γ-mercaptopropyldi(trimethylsiloxy)methylsilane (MD(SH)M), to functionalize fiber-based substrates (i.e., stainless steel mesh, cotton fiber) for oil decontamination processes including oil–water separation, oil absorption and demulsification. The functionalized stainless-steel mesh (SSM@PM) can completely separate water and oils of high/low density without prewetting by oil. The functionalized cotton fibers (CF@PM) can absorb different oils from water without being wetted by water and maintain excellent oil absorption performance even after 10 cyclic reuses. Besides, CF@PM shows good demulsification performance to water-in-oil emulsions stabilized by span 80 and asphaltenes. The underlying interaction mechanisms are investigated using force measurements. The CF@PM shows much stronger repulsion to water droplets in air as compared to unmodified cotton fiber, and SSM@PM has strong attraction to oil droplets under water but almost no attraction to water droplets in oil, accounting for the effective oil/water separation capacity. Such strong attraction between oil and MD(SH)H-modified surfaces can be attributed to the hydrophobic interaction as confirmed by surface force measurements. This work provides a facile surface functionalization approach with great potential applications in oil/water separation and demulsification of surfactant- or asphaltenes-stabilized emulsions.

Pore-scale study on interfacial force-induced residue mobilization under immiscible ternary fluids flow

Immiscible three-phase flow and the trapping/mobilizing mechanism are significant to many water and energy applications such as water infiltration, oily wastewater treatment, CO2 sequestration, and water-alternating-gas (WAG) for oil recovery enhancement. This work targets the ternary fluid system, namely water, gas, and oil, to uncover the significant role of interfacial forces in the transient flow behavior and trapped-phase mobilization. From both the lattice Boltzmann method (LBM) modeling and experimental observations, we firstly showed the deformation and mobilization process of the oil droplet when interacting with water droplet in air. The re-distribution of oil phase reveals the strong interfacial interactions at the water-gas-oil three-phase contact point (fluid-TPCP). For the more complicated three-phase flow in porous media, our visualization results also showed that the trapped oil phase, which initially adhered to rough surfaces or inside dead-end pores, was extracted by the pulling effect at fluid-TPCP during WAG injection. The influence of surface wettability conditions residue extraction efficiency was also discussed. This work provides insightful understandings of the interfacial forces in mobilizing the residues under immiscible three-phase flow in porous media.

Gravitational collision efficiencies of small viscous drops at finite Stokes numbers and low Reynolds numbers

Collision efficiencies are calculated for two sedimenting spherical drops of different radii with internal circulation under conditions such that drop inertia can be significant while the surrounding fluid inertia remains negligible. A trajectory analysis is employed with exact methods for determining the hydrodynamic forces. When the Reynolds number is small, fluid inertia is negligible, and the hydrodynamic forces are linear functions of the velocities of the drops. However, at nonzero Stokes numbers, drop inertia must be taken into account, and the hydrodynamic forces do not balance the applied forces. For drops in close approach, lubrication forces, slip and attractive molecular forces are considered. Comparison is made between the effects of unretarded and retarded van der Waals forces and Maxwell slip on collision efficiencies. Slip is calculated exactly for viscous drops using bispherical coordinates for motion along the drops’ line of centers. For water droplets in air, at drop radii between 10 and 30μm, drop inertia is important while the Reynolds based on the surrounding air is still small. The collision efficiency goes through a minimum and then approaches the Smoluchowski limit of no hydrodynamic interactions as the drop size and Stokes number become increasingly large. Viscous effects are most important at drop radii of about 15μm. For drops with a radius less than 10μm, the most significant factors are unretarded van der Waals forces, Maxwell slip, and retarded van der Waals forces, respectively. When van der Waals forces and slip are combined, the collision efficiencies for drops with radii of 10μm are significantly greater than the results of previous researchers. At an intermediate drop radius of 20μm, surrounding fluid inertia, as considered in earlier work, appears to lead to greater collision efficiencies at intermediate size ratios, while van der Waals forces, incorporated in the present study, cause larger values at smaller and larger size ratios. At a drop radius of 30μm, drop inertia dominates interactions, and similar results occur for both the current and prior investigations. Since temperature affects both density and viscosity, collision efficiencies can differ by a factor of two or more between 0 °C and 100 °C at certain drop radii. Change in the viscosity ratio itself leads to about a 7% difference in the collision efficiency between drops with internal circulation and solid spheres at room temperature.

A Comprehensive Investigation into the Effect of a Low Surface Energy Treatment on Gas Hydrate, Asphaltene, and Wax Formation, Deposition, and Adhesion

SummaryThe formation/precipitation and deposition of pipeline solids, such as gas hydrates, asphaltenes, and waxes have long plagued production fields. Given the vast differences in chemistries of these solids, any current prevention or mitigation strategy, particularly for cases in which multiple issues are a concern, is likely to involve an extensive assortment of chemical additives that are both costly and add complexity to the system. Surface treatments (coatings), on the other hand, present a relatively viable option for management strategies. A chemically and physically robust surface treatment with the ability to address deposition issues for multiple pipeline solids could not only decrease the operating expenditures for a field through material cost savings and obviation of downstream separation, but could also simplify produced fluids by eliminating additional chemicals from the mixture.The purpose of this study was to explore the feasibility of a particular surface treatment as part of a solids management strategy. This work used an omniphobic surface treatment to probe its effects on gas hydrate, asphaltene, and wax deposition. Specifically, an interfacial tensiometer (IFT) collected contact angle measurements for wettability studies. High-pressure rocking cells studied gas hydrate nucleation and deposition. A bench-scale flow loop quantified the deposition of oil and asphaltenes after a set time period. Finally, a mechanical shear device measured the adhesion force of wax deposits on untreated/treated surfaces.Static contact angle results showed that the omniphobic surface treatment had reduced surface interaction with water droplets in air, altering from the complete wetting on corroded surfaces to slightly hydrophobic conditions of greater than 100°. In addition, rocking-cell tests indicated that these omniphobic surface treatments may prevent gas hydrate deposition for up to 72 hours. The gas hydrate rocking-cell tests also demonstrated possible increases in induction time and occasional elimination of hydrate nucleation with the surface treatment. Finally, the surface treatment application, which also decreased surface roughness, showed that crude oil and asphaltene particles deposition, as well as the shear required to remove solidified wax deposits, could be reduced by a large factor. Overall, promising results were recorded for all major flow-assurance solids in the presence of the surface treatment.

SIMULATION OF A WATER CURTAIN APPLICATION TO PROTECT WORKERS FROM THERMAL INJURIES

Problem statement. The problem of evaluating the effectiveness of using the water curtain to reduce the risk of thermal injury to people in a fire is considered. The problem is to determine the temperature fields when supplying water for air cooling. The purpose of the article. Development of a numerical model for calculating the process of propagation of water droplets in the air, their evaporation to reduce the temperature of heated air due to fire. Methodology. For mathematical modeling of the process of propagation of water droplets in air, thermal air pollution, the convective-diffusion equation of mass transfer, the energy equation and the equation describing the motion of an ideal liquid (potential flow model) are used. The potential flow model allows you to quickly determine the field of air flow velocity in areas with a complex geometric shape. Implicit difference splitting schemes are used for numerical integration of the convective-diffusion mass transfer equation and the energy equation. Physical splitting of basic equations is used to construct a difference analogue of modeling equations. The Richardson method and the conditional approximation scheme are used to solve the aerodynamics problem of determining the velocity potential field and the components of the air velocity vector. An engineering method for calculating the process of evaporation of a drop of water based on Sreznevsky's law has been developed. Scientific novelty. An effective numerical model has been developed that allows the method of computational experiment to determine the efficiency of using the water curtain to reduce the level of thermal pollution of atmospheric air due to fire. The numerical model is based on the integration of the fundamental equations of aerodynamics, heat and mass transfer. The model takes into account the most significant physical factors that affect the process under study: the movement of heated air, the movement of water droplets in the air, evaporation of the droplet, and so on. Practical significance. Based on the built model, a computer code has been created that allows you to quickly determine the temperature fields in the air when using a water curtain. The numerical model will be useful when conducting computational experiments for the purpose of scientifically sound choice of the location of the water curtain in case of fire. Conclusions. A computer code has been created that allows a computational experiment to investigate the effectiveness of using a water curtain in a fire. The developed computer program can be implemented on low and medium power computers. The results of a computational experiment are presented.

Measuring Droplets Expelled During Endoscopy to Investigate COVID-19 Transmission Risk

Measuring Droplets Expelled During Endoscopy to Investigate COVID-19 Transmission Risk

In silico investigation of the evaporation flux distribution along sessile droplet surfaces during convective drying

A finite volume model capable of predicting the influence of gas flow on the evaporation flux profile of sessile droplets during convective drying is presented. Evaporation flux distributions originating under a variety of conditions and at various stages in the drying process of water droplets in air are investigated and quantified. As an extension to already existing models this numerical simulation takes the advection of vapor in the flow field and the hereby arising concentration gradient shift along the droplet surface into account. This allows for a representation of not only the overall convective drying process, but particularly the resulting local evaporation at different stages and under different flow conditions. Finally, the influence of another droplet present in the vicinity is analyzed with special regard to surface flux distribution. Latter, and indices evaluated from it, is seen as an indicator for solids transport in the droplet and for deposit formation.

Analysis of radiation-induced cooling and growth of mist and cloud droplets

Radiative heat transfer from a dilute, optically thin assembly of water droplets in air to a remote heat sink (e.g., cloud tops to outer space) is analyzed, including droplet-vapor conduction, vapor-phase mass transfer, and liquid-vapor phase change. Predictions are compared with a recent laboratory study and show improvement over preliminary modeling efforts [Brewster et al. 2020]. Results highlight: (i) the validity of the quasi-steady vapor-supersaturation assumption, (ii) the importance of unintended droplet solution effects, and (iii) the effects of internal (isothermal) equilibration of droplet-surface supersaturations vs. external (radiative cooling) equilibration on droplet growth. This analysis produces simple formulas for the time scales for condensational growth and for cooling or thermal equilibration of radiatively cooled, emitting/absorbing, conducting, and condensing droplets under near-saturation conditions. Both time scales—growth and cooling—are of the order of minutes. The growth time scale is a strong function of temperature and the cooling time scale is a strong function of droplet volume fraction. The growth time scale decreases, i.e., the process goes faster, for warmer droplets, e.g., with simultaneous conductive heating; it also decreases as droplet diameter decreases, indicating that radiatively-induced growth can happen even for small (< 1 µm diameter) droplets. The cooling time scale, a modification of the corresponding time scale for non-volatile (non-condensing) droplets, varies inversely with droplet volume fraction. The cooling time is analogous to the classical result for lumped-capacitance (low Biot-number), convective-conductive cooling. A dimensionless factor is identified that represents the fractional increase in radiative cooling time due to condensation, which arises from latent energy supplied by condensation that would have been drawn out of the vapor internal energy for non-condensing droplets. A simple thermophysical formula is presented for estimating this factor, which exhibits significant temperature dependence (primarily through water-vapor mole fraction) and varies from 67% at 272 K to 230% at 293 K, 1 bar. A conduction-radiation parameter is also identified that characterizes the importance of conductive/convective heating by surrounding air, when that mode competes with radiative cooling, and quantifies how closely droplets radiating to a remote sink at a fixed temperature can approach that temperature, given enough time. These results bring to light an important distinction between the cooling and droplet-growth effects of droplet radiation and the dependence of these effects on competition between radiative cooling and conductive/convective heating. When conductive heating is negligible, significant droplet growth and cooling both occur, within minutes; with conductive heating present, the cooling effect is diminished while the growth effect is enhanced. These findings have implications for modeling cloud microphysics, both with respect to liquid droplets overcoming the condensation-coalescence barrier in “warm” (non-freezing) clouds and with respect to droplets freezing in “cold” clouds.

Optical Manipulation of Water Droplets in Air by a Double-beam Laser Trapping Technique

When micrometer-sized water droplets are levitated in air, thermodynamic metastable states are stable for a long time because they are not affected by the solid surface that provides a scaffold for nucleation. Therefore, it is expected that the use of aerosol droplets as a microreactor would allow chemical processes that are different from those under thermal equilibrium to proceed. The purpose of this study is to construct a double-beam laser trapping system to simultaneously manipulate two water droplets in air, and then to contact and fuse the droplets at an arbitrary timing. Using this system, the effect of surface charge was investigated when water droplets coalesce in air.

Friction behavior of silicone rubber hemisphere under non-uniform wetting states: With water droplets in air or air bubbles in water

The friction behavior of rubber is sensitive to real contact formation, especially on flat floors, and it can be determined by the wetting distribution (uniform or non-uniform). Here, we investigated the friction behavior and contact condition between a rubber hemisphere and a glass plate under non-uniform wetting conditions with water droplets in air and air bubbles in water. The experimental results indicated that the friction coefficient and real contact area for non-uniform wetting conditions were higher than for uniform wetting conditions without water droplets and air bubbles. Considering non-uniform wetting, a dewetting theory was developed that explains promotion of real contact formation.

Scattering of an utlrashort laser pulse by a spherical air bubble.

The scattering of an ultrashort laser pulse by an air bubble in water is investigated by means of the Lorenz-Mie theory and the Debye expansion. A 70 fs, 800 nm pulse is considered as a plane wave with a Gaussian temporal envelope. The transient response is treated with the theory derived from Gouesbet and Gréhan [Part. Part. Syst. Charact.17, 213-224 (2000)], taking now into account chromatic dispersion and absorption of water. It is observed that contrary to the case of water droplet in air, the Debye modes p ≥ 1 start their transient scattering at the same time and the same angle (≈90°) and for a large size parameter, they differentiate as time elapses. A parametric study on the size parameter and the spatial extension of the pulse is performed to identify regimes where the different Debye mode are distinguishable in time. Dependence on the scattering angle is also treated. Finally, by considering pulse chirp, it is shown that the laser/bubble distance has an influence on the separability of modes p = 0 and p = 1.