Numerical Solution on Spherical Vacuum Bubble Collapse Using MPS Method

2009 ◽  
Author(s):  
Wenxi Tian ◽  
Suizheng Qiu ◽  
Guanghui Su ◽  
Yoshiaki Oka
Keyword(s):  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Liquid Pool ◽  
Bubble Collapse ◽  
Bubble Liquid ◽  
Mps Method ◽  
Noncondensable Gas ◽  
Cavitation Phenomenon ◽  
Rebound Phenomenon ◽  
Good Agreement

In this study, the vacuum bubble collapse in liquid pool has been simulated using MPS code. The liquid is described using moving particles and the bubble-liquid interface was set to be vacuum pressure boundary without interfacial heat mass transfer. The motion and location of interfacial particles can be competent in configurating the topological shape of vacuum bubble. The time dependent bubble diameter, interfacial velocity and bubble collapse time were obtained under wide parametric range. The comparison with Rayleigh’s prediction showed a good agreement which validates the applicability and accuracy on MPS method in solving present momentum problems. The potential void-induced water hammer pressure pulse was also evaluated which is instructive for cavitaion erosion study. The bubble collapse with noncondensable gas has also been simulated and the rebound phenomenon was successfully captured which is similar with vapor-filled cavitation phenomenon. The present study exhibits some fundamental characteristics of vacuum bubble hydrodynamics and it is also expected to be instructive for further applications of MPS method to in complicated bubble dynamics.

Numerical Solution on Spherical Vacuum Bubble Collapse Using MPS Method

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Wen xi Tian ◽  
Sui-zheng Qiu ◽  
Guang-hui Su ◽  
Yuki Ishiwatari ◽  
Yoshiaki Oka
Keyword(s):  
Cavitation Erosion ◽  
Bubble Dynamics ◽  
Pressure Pulse ◽  
Bubble Diameter ◽  
Bubble Collapse ◽  
Interfacial Velocity ◽  
Bubble Liquid ◽  
Mps Method ◽  
Good Consistency ◽  
Moving Particle

Single vacuum bubble collapse in subcooled water has been simulated using the moving particle semi-implicit (MPS) method in the present study. The liquid is described using moving particles, and the bubble-liquid interface was set to be the vacuum pressure boundary without interfacial heat mass transfer. The topological shape of the vacuum bubble is determined according to the location of interfacial particles. The time dependent bubble diameter, interfacial velocity, and bubble collapse time were obtained within a wide parametric range. Comparison with Rayleigh’s prediction indicates a good consistency, which validates the applicability and accuracy of the MPS method. The potential void-induced water hammer pressure pulse was also evaluated, which is instructive for the cavitation erosion study. The present paper discovers fundamental characteristics of vacuum bubble hydrodynamics, and it is also instructive for further applications of the MPS method to complicated bubble dynamics.

Jetting of viscous droplets from cavitation-induced Rayleigh–Taylor instability

2018 ◽  
Vol 846 ◽  
pp. 916-943 ◽  
Author(s):  
Qingyun Zeng ◽  
Silvestre Roberto Gonzalez-Avila ◽  
Sophie Ten Voorde ◽  
Claus-Dieter Ohl
Keyword(s):  
Bubble Dynamics ◽  
Stokes Equations ◽  
Droplet Surface ◽  
Taylor Instability ◽  
Bubble Collapse ◽  
Fluid Viscosity ◽  
Analytic Model ◽  
Radial Acceleration ◽  
Rayleigh Taylor Instability ◽  
Good Agreement

Liquid jetting and fragmentation are important in many industrial and medical applications. Here, we study the jetting from the surface of single liquid droplets undergoing internal volume oscillations. This is accomplished by an explosively expanding and collapsing vapour bubble within the droplet. We observe jets emerging from the droplet surface, which pinch off into finer secondary droplets. The jetting is excited by the spherical Rayleigh–Taylor instability where the radial acceleration is due to the oscillation of an internal bubble. We study this jetting and the effect of fluid viscosity experimentally and numerically. Experiments are carried out by levitating the droplet in an acoustic trap and generating a laser-induced cavitation bubble near the centre of the droplet. On the simulation side, the volume of fluid method (OpenFOAM) solves the compressible Navier–Stokes equations while accounting for surface tension and viscosity. Both two-dimensional (2-D) axisymmetric and 3-D simulations are performed and show good agreement with each other and the experimental observation. While the axisymmetric simulation reveals how the bubble dynamics results destabilizes the interface, only the 3-D simulation computes the geometrically correct slender jets. Overall, experiments and simulations show good agreement for the bubble dynamics, the onset of disturbances and the rapid ejection of filaments after bubble collapse. Additionally, an analytic model for the droplet surface perturbation growth is developed based on the spherical Rayleigh–Taylor instability analysis, which allows us to evaluate the surface stability over a large parameter space. The analytic model predicts correctly the onset of jetting as a function of Reynolds number and normalized internal bubble energy.

Numerical Simulations of Dynamics and Heat Transfer Associated With a Single Bubble in the Presence of Noncondensables

2007 ◽  
Author(s):  
Jinfeng Wu ◽  
Vijay K. Dhir
Keyword(s):  
Heat Transfer ◽  
Bubble Dynamics ◽  
Numerical Procedure ◽  
Saturation Temperature ◽  
Bubble Surface ◽  
Moving Mesh Method ◽  
Bubble Liquid ◽  
Noncondensable Gas ◽  
Noncondensable Gases ◽  
Level Set Function

Under subcooled boiling conditions, the liquid may contain dissolved noncondensabe gases. During phase change at the bubble-liquid interface, noncondensable gases will be injected into the bubble along with vapor. Due to heat transfer into sub-cooled liquid, vapor will condense in the upper regions of the bubble and the bubble interface is impermeable to noncondensables. As a result, noncondensabe gases will accumulate at the top of bubbles. This existing gradient of noncondensable concentration inside bubble determines the saturation temperature gradient around the bubble surface. The nonuniform saturation temperature may cause a difference in surface tension which would give rise to thermocapillary convection in the vicinity of the interface. So far, this description is merely a hypothesis. It is felt that much inspection is in vital demand to clarify the uncertainty as to the role of noncondensables throughout this process. In this study, air is taken as noncondensable gas, and the aim is to investigate the effects of noncondensable air on heat transfer and bubble dynamics. The results from a numerical procedure coupling level set function with moving mesh method show the evidence of effects of noncondensable air imposed on heat transfer and the induced flow pattern is presented as well.

Numerical Simulation of Dynamics and Heat Transfer Associated With a Single Bubble in Subcooled Boiling and in the Presence of Noncondensables

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Jinfeng Wu ◽  
Vijay K. Dhir
Keyword(s):  
Heat Transfer ◽  
Thermocapillary Convection ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Saturation Temperature ◽  
Subcooled Boiling ◽  
Bubble Liquid ◽  
Subcooled Liquid ◽  
Noncondensable Gases ◽  
Induced Flow

During phase change at the bubble-liquid interface, under subcooled boiling conditions, noncondensable gases dissolved in the liquid will be injected into the bubble along with vapor. Due to heat transfer into subcooled liquid, vapor will condense in the upper regions of the bubble while noncondensables will continue to accumulate. Subsequently, thermocapillary convection caused by nonuniform saturation temperature at the interface may occur. The aim of this work is to investigate the effects of noncondensables on heat transfer and bubble dynamics. The numerical results show that the effects of noncondensables on 5°C subcooled boiling of water are minor in terms of the equilibrium bubble diameter and overall Nusselt number. However, induced flow pattern around the bubble is altered, especially under reduced gravity conditions.

Theoretical Modeling and Experimental Measurements of Single Bubble Dynamics From a Submerged Orifice in a Liquid Pool

2007 ◽  
Author(s):  
S. K. Kasimsetty ◽  
A. Subramani ◽  
R. M. Manglik ◽  
M. A. Jog
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Liquid Pool ◽  
Orifice Diameter ◽  
Equivalent Diameter ◽  
Bubble Behavior ◽  
Balance Of Forces ◽  
Submerged Orifice

The dynamics of a single gas bubble, emanating from a submerged orifice in stagnant water has been explored both theoretically and experimentally. The mathematical model represents a fundamental balance of forces due to buoyancy, viscosity, surface tension, liquid inertia, and gas momentum transport, and the consequent motion of the gas-liquid interface. Theoretical solutions describe the dynamic bubble behavior (incipience, growth and necking) as it grows from a tip of a sub-millimeter-scale capillary orifice in an isothermal pool of water. These results are also found to be in excellent agreement with a set of experimental data that are obtained from optical high-speed micro-scale flow visualization. Variations in bubble shape, equivalent diameter, and growth times with capillary orifice diameter and air flow rates are outlined. These parametric trends suggest a two-regime ebullient transport: (a) a constant volume regime where the bubble diameter is not affected by the flow rate, and (b) a growing bubble regime where bubble size increases with flow rate.

The Effect of the Time Dependent Pressure Difference on Bubble Dynamics in Microchannels

2006 ◽  
Author(s):  
Aidin Keikhaee ◽  
Shahin Rouhani ◽  
Yadollah Saboohi
Keyword(s):  
Pressure Difference ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Bubble Formation ◽  
Density Perturbation ◽  
Time Dependent ◽  
Time Dependency ◽  
Physical Processes ◽  
Fundamental Understanding ◽  
Good Agreement

The physical processes responsible for bubble formation in microchannels are not well understood and lack fundamental understanding. Experimental results are not exactly in agreement with each other and there are no definite theories to explain the possible effects of different parameters. Among different parameters the microchannel hydraulic diameter can affect the bubble formation mechanism in microchannels strongly. In this paper the effect of the time dependent pressure difference between inside and outside of the bubble on bubble dynamics in microchannels have been investigated. The source of this time dependency can be the emergence of bubble embryos which produces a density perturbation in liquid. Results show that bubble growth rate and maximum bubble diameter in microchannels are smaller than them in ordinary size channels. These results are in good agreement with some researchers’ observations, sometimes called fictitious boiling and bubble-extinction, in microchannels.

The Boundary Integral Method Applied to Non-Spherical Cavitation Bubble Growth and Collapse Close to a Rigid Boundary

2015 ◽  
Author(s):  
Ali Alhelfi ◽  
Bengt Sunden
Keyword(s):  
Cavitation Bubble ◽  
Integral Method ◽  
Bubble Dynamics ◽  
Boundary Integral ◽  
Solid Surfaces ◽  
Boundary Integral Method ◽  
Bubble Collapse ◽  
Surface Erosion ◽  
Rigid Boundary ◽  
Cavitation Phenomenon

Recently much attention has been paid to studies concerning bubble dynamics in the cavitation phenomena and this topic has been the subject of many research works. In fact, the simulation of non-spherical bubble dynamics and its interaction with solid boundaries have received much less attention due to the complexity of the problem. One of the main reasons of the structural damages in the cavitation phenomenon is due to the formation of micro jets generated due to the bubble collapse and impinging on the solid surfaces or boundaries. The boundary integral method (BIM) based on Green’s function is used to model the oscillation and collapse of a cavitation bubble close to a rigid boundary. The liquid is considered to be incompressible, inviscid, and irrational around the bubble. These assumptions satisfy the conditions for the Laplacian equation. The theory permits one to predict correctly the interaction between the bubble and the rigid boundary, which is of great importance in the study of cavitation damage due to a bubble collapsing close to the boundaries. The results reveal that the amplitude of bubble oscillation depends on the bubble location away from a rigid surface. Also, the theory for the cavitation bubble dynamics presented in this study has many advantages in various situations and might be helpful to understand effects of the cavitation phenomenon such as generation of excessive vibration, surface erosion and undesirable acoustic emission.

scholarly journals Numerical simulations of non-spherical bubble collapse

2009 ◽  
Vol 629 ◽  
pp. 231-262 ◽  
Author(s):  
ERIC JOHNSEN ◽  
TIM COLONIUS
Keyword(s):  
Bubble Dynamics ◽  
High Pressures ◽  
Pressure Ratio ◽  
Free Field ◽  
Water Hammer ◽  
Incident Shock ◽  
Bubble Collapse ◽  
Shock Propagation ◽  
Potential Damage ◽  
Very High

A high-order accurate shock- and interface-capturing scheme is used to simulate the collapse of a gas bubble in water. In order to better understand the damage caused by collapsing bubbles, the dynamics of the shock-induced and Rayleigh collapse of a bubble near a planar rigid surface and in a free field are analysed. Collapse times, bubble displacements, interfacial velocities and surface pressures are quantified as a function of the pressure ratio driving the collapse and of the initial bubble stand-off distance from the wall; these quantities are compared to the available theory and experiments and show good agreement with the data for both the bubble dynamics and the propagation of the shock emitted upon the collapse. Non-spherical collapse involves the formation of a re-entrant jet directed towards the wall or in the direction of propagation of the incoming shock. In shock-induced collapse, very high jet velocities can be achieved, and the finite time for shock propagation through the bubble may be non-negligible compared to the collapse time for the pressure ratios of interest. Several types of shock waves are generated during the collapse, including precursor and water-hammer shocks that arise from the re-entrant jet formation and its impact upon the distal side of the bubble, respectively. The water-hammer shock can generate very high pressures on the wall, far exceeding those from the incident shock. The potential damage to the neighbouring surface is quantified by measuring the wall pressure. The range of stand-off distances and the surface area for which amplification of the incident shock due to bubble collapse occurs is determined.

Droplet and Bubble Dynamics in Saturated FC-72 Spray Cooling

2005 ◽  
Author(s):  
Ruey-Hung Chen ◽  
David S. Tan ◽  
Kuo-Chi Lin ◽  
Louis C. Chow ◽  
Alison R. Griffin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Bubble Dynamics ◽  
Bubble Diameter ◽  
Spray Cooling ◽  
Transfer Enhancement ◽  
Secondary Nucleation ◽  
Bubble Density ◽  
Experimental Findings ◽  
Small Bubbles ◽  
Nucleation Bubble

Droplet and bubble dynamics and nucleate heat transfer in saturated FC-72 spray cooling were studied using a simulation model. Using the experimentally observed bubble growth rate, submodels were assumed based on physical reasoning for the number of secondary nuclei entrained by the impinging droplets, bubble puncturing by the impinging droplets, bubble merging and the spatial distribution of secondary nuclei. The predicted nucleate heat transfer was in agreement with experimental findings. Dynamic aspects of the droplets and bubbles, which had been difficult to observe experimentally, and their ability in enhancing nucleate heat transfer were then discussed based on the results of the simulation. These aspects include bubble merging, bubble puncturing by impinging droplets, secondary nucleation, bubble size distribution and bubble diameter at puncture. Simply increasing the number of secondary nuclei is not as effective in enhancing nucleate heat transfer as when it is also combined with increased bubble puncturing frequency by the impinging droplets. For heat transfer enhancement, it is desirable to have as many small bubbles and as high a bubble density as possible.

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