Numerical Simulation of Bubble Impact and Movement alongside Inclined plate with VOF Method [in Persian]
Abstract
n present study, the impact of single bubble on an inclined wall and its movement is
investigated by applying volume of fluid method (VOF) in OpenFOAM open source cfd package
using solver called interFoam. Both phases are incompressible and surface tension between the
two phases is estimated by CSF method. The effect of some parameters such as contact angle, wall
slope and Bond and Morton dimensionless numbers on bubble shapes and velocity are studied.
The numerical results show bubble velocity along wall increases with the increase of wall slope
angle. Three bubble regimes are recognized and introduced in this study named: sliding,
bouncing, and zigzagging based on wall slope. The bubble regime changes from sliding to
bouncing when wall slope changes from 30 to 40 degrees. In constant Morton number, increment
of Bond number increases both velocity and amplitude of fluctuations. In addition, an increment
of Morton number in constant Bond number decreases velocity and amplitude of fluctuations.
Moreover, by increment of Morton number, the bubble motion will change from an accelerating
motion to constant velocity condition.
... Bubbles, drops, and particles [2] Investigation of transport phenomena in a vapour film formed in contact between hot metallic sphere and water [3] Modeling the growth of a vapor film formed in contact between a hot metal sphere and water in pressure vessels [4] An interface-capturing method for incompressible two-phase flows. Validation and application to bubble dynamics [5] The stability of vapor film immersed in superfluid helium on the surface of the hot ball [6] Simulating the rise characteristics of gas bubbles in liquids using CFD [7] A study of drift velocity in bubbly two-phase flow under microgravity conditions [8] Numerical simulation of gas bubbles behaviour using a three-dimensional volume of fluid method [9] Bubbles in viscous liquids: Shapes, wakes and velocities [10] Numerical simulation of bubble impact and movement alongside to the inclined plate with VOF method [11] Numerical simulation and investigation of bubble velocity and deformation in inclined channel with two consecutive slopes using VOF-PLIC method [12] Simulation of oblique coalescence of a pair of bubbles using Level Set method [13] A coupled volume-offluid/level-set method for simulation of two-phase flows on unstructured meshes [14] Two-dimensional bubble rising through quiescent and non-quiescent fluid: Influence on heat transfer and flow behavior [15] Numerical simulation of bubble rising behavior in liquid LBE using diffuse interface method [16] An extended volume of fluid method and its application to single bubbles rising in a viscoelastic liquid [17] Drop impact onto a liquid layer of finite thickness: Dynamics of the cavity evolution [18] Quantitative benchmark computations of two-dimensional bubble dynamics Investigating the history of production and dynamics of growing or collapsing bubbles under various environmental conditions plays an important role in the correct understanding of the process of boiling, evaporation, cavitation, and condensation. In this paper, the rising shape regime the air bubble injected into the water column was studied and simulated using numerical and experimental methods. ...
1] Bubbles, drops, and particles [2] Investigation of transport phenomena in a vapour film formed in contact between hot metallic sphere and water [3] Modeling the growth of a vapor film formed in contact between a hot metal sphere and water in pressure vessels [4] An interface-capturing method for incompressible two-phase flows. Validation and application to bubble dynamics [5] The stability of vapor film immersed in superfluid helium on the surface of the hot ball [6] Simulating the rise characteristics of gas bubbles in liquids using CFD [7] A study of drift velocity in bubbly two-phase flow under microgravity conditions [8] Numerical simulation of gas bubbles behaviour using a three-dimensional volume of fluid method [9] Bubbles in viscous liquids: Shapes, wakes and velocities [10] Numerical simulation of bubble impact and movement alongside to the inclined plate with VOF method [11] Numerical simulation and investigation of bubble velocity and deformation in inclined channel with two consecutive slopes using VOF-PLIC method [12] Simulation of oblique coalescence of a pair of bubbles using Level Set method [13] A coupled volume-of-fluid/level-set method for simulation of two-phase flows on unstructured meshes [14] Two-dimensional bubble rising through quiescent and non-quiescent fluid: Influence on heat transfer and flow behavior [15] Numerical simulation of bubble rising behavior in liquid LBE using diffuse interface method [16] An extended volume of fluid method and its application to single bubbles rising in a viscoelastic liquid [17] Drop impact onto a liquid layer of finite thickness: Dynamics of the cavity evolution [18] Quantitative benchmark computations of two-dimensional bubble dynamics Investigating the history of production and dynamics of growing or collapsing bubbles under various environmental conditions plays an important role in the correct understanding of the process of boiling, evaporation, cavitation, and condensation. In this paper, the rising shape regime the air bubble injected into the water column was studied and simulated using numerical and experimental methods. For this purpose, a column filled with water was used in the laboratory as a host fluid and using the high-speed image recording method, the most important hydrodynamic properties of the bubbles, such as velocity, size, pathway, and other bubble properties were measured. Then, using the computational fluid dynamics and the volume of fluid two-phase flow model, ascent and deformation of the single-bubble injected into a stationary reservoir were investigated and compared with previous and current experimental and numerical results. The result of this validation with a good approximation was in accordance with the reference results and it proved the correctness of the solver's and its settings. Finally, the bubble shape regime was calculated by the non-dimensional numbers of Eötvös and Morton and compared with the numerical simulation and empirical test. The regime obtained from the Clift diagram is a spherical cap regime, which at the same conditions, is in accordance with the bubble shaped regime simulated by numerical and experimental methods and this confirms the validity of the numerical solution.
In the present simulation, a solver called phaseChangeHeatFoam is implemented under open source CFD code OpenFOAM to consider boiling and condensation. The solver is capturing interface among two immiscible phases using a color function volume of fluid. The two fluids (vapor and liquid) are assumed Newtonian and incompressible. The surface tension between liquid-vapor phases is accounted using continuous surface force (CSF) model. The spurious current in CSF model is reducing using filter and s-CLSVOF method. The mass flux rate across the interface is determined by Lee, Tanasawa or Fourier mass transfer models in the present attempt. Additionally, the variation of saturation temperature with local pressure is considered with Clausius-Clapeyron relation. The coupled velocity pressure equation is solved using PISO algorithm.
Our studies show the spurious current is reduced up to 1 order in the simulation of stagnant bubble problem using present implemented methods. These methods also increase the accuracy of pressure jump calculation. Additionally, the present comparison shows not only filter method is simple to implement but also it is as efficient as s-CLSVOF method in calculation of curvature and reducing spurious current. The new solver is validating with (i) Stefan problem, (ii) two-dimensional film boiling, (iii) the film condensation on horizontal plate, (iv) the laminar film condensation over vertical plate. To estimate the accuracy of present solver in different conditions, saturation water at different saturation pressures are chosen up to high density ratio of 1000. The comparison between present numerical simulations and analytical solutions and previous sharp interface method simulations shows present solver has a high accuracy in simulation of phase change flow despite of using diffuse interface method (DIM). Then phase change phenomena in vapor bubble rising in subcooled and saturated liquid are studied and compared with available experimental data. Our numerical studies show bubble life time has linear relation with bubble size but it is not dependent on initial bubble shape in subcooled fluid. There is a non-linear relation between bubble life time and subcooled temperature which is consistent with sudhoff correlation. Moreover, bubble survives longer in bubble swarm condensation due to being placed in the thermal boundary layer of up-front bubbles. The simulation of superheat vapor bubble in saturated water shows bubble size increases due to evaporation at first. However, it collapses finally due to condensation. Here, the bubble life time is proportional with vapor bubble superheat temperature. The present study shows the capability of diffuse interface method in accurate simulation of phase change process and gives some fundamental information about vapor bubble rising which is expected to be instructive for further applications.
Gas bubble formation and rise velocity beneath a downward-facing inclined surface submerged in a liquid were experimentally investigated under atmospheric conditions. The gas was injected into the liquid through a small diameter tube at constant gas flowrate and the gas bubble formation and detachment processes were recorded using video equipment. The effects of inclination angle, injection tube diameter and gas flowrate upon the bubble volume at detachment and the bubble rise velocity were examined. The injected gas flowrate ranged from 18 to 166ml/s. Tap water and air were used as the experimental fluids. Some of the preliminary experimental results obtained are presented. (A)
The interaction of particles with vortices is important in many technological and environmental applications. The primary effect of vortical flows on suspended particles and droplets is to generate a dispersion pattern in which the particulate phase tends to migrate from the vortex core and concentrate on the edges of the vortices. Note that this is the exact opposite to the behaviour of bubbles interacting with vortices (Chapter XVIII), because the particulate phase is more dense than the fluid phase. The resulting dispersion of the particles is important in the design of combustion systems in which the degree of mixing controls combustion efficiency and the generation of soot. Also, the effectiveness of wire and plate electrostatic precipitators depends on the interaction of the particles with the vortices generated by the supporting structure. The spread of fires by firebrands entrained by large scale vortices in atmospheric flows is another example of the importance of particle interaction with vortices. Several other important industrial and environmental applications are discussed in a recent review article by Hunt (1991).
The shapes and terminal velocities of bubbles rising in viscous liquids have been determined. For Morton numbers (M) greater than 4 multiplied by 10** minus **3 the drag coefficient and dimensionless bubble shape are functions only of Reynolds number (R). Shape regimes and terminal rise velocities have been correlated. The flow field around a rising bubble was visualized through the hydrogen bubble tracer technique. For M greater than 4 multiplied by 10** minus **3 and R less than 110 the bubbles trailed closed, laminar toroidal wakes. For R greater than 110 the wake was open and unsteady. Streamlines for the flow were obtained by raising a cine camera at the same speed as the bubble and filming the H//2 tracer bubbles. Results are presented for R less than 150 and 7. 4 multiplied by 10** minus **4 less than M less than 850. Refs.
An experimental study was conducted to measure rise velocities of air bubbles along an inclined flat wall for small Weber numbers. In the case of a freely rising air bubble, good agreement was obtained with the theoretical drag coefficient values of Ryskin and Leal. Fór a given working fluid, the rise velocity decreased monotonically as the confining wall was inclined from the vertical. For the case of a nearly vertical confining wall, the rise velocities were in good agreement with Hestroni et al.'s analysis as long as the air bubbles were nearly spherical. The drag coefficients of the bubbles were found to be uniquely correlated with the bubble Reynolds number and the Eotvos number, modified to account for the angle of inclination of the confining wall. The Reynolds number varied from 0.3 to 130 with the Weber number varying from 0.008 to 1.6.
The problem of determining the rate of rise of large gas bubbles in an infinite volume and a vertical tube is considered. In the first case the shape of the bubble is constructed by ``gluing together'' the front surface immersed in a flow of ideal liquid and the rear surface being formed under the action of gravitational and capillary forces, and in the second case the solution of the Laplace equation is constructed for the velocity potential in the problem of ideal liquid flow in a tube around a semiinfinite cylindrical body with a hemispherical frontal part.
A bubble rising beween two inclined parallel walls is investigated numerically. Stokes flow is assumed and we use a boundary integral method to solve the problem. Computations were done for channels inclined at various angles, different flow rates, and for different parameters. We determined the bubble rise velocity as a function of angle of inclination and it is in accordance with published experimental results done at low Reynolds numbers. It was also found that bubble snap off can occur for large Bond numbers.
The behavior of bubbles with radii of 0.5–0.7 mm rising through water in the presence of a solid boundary were observed using a high-speed video camera. Fluid inertia and surface tension cause a bubble to bounce several times from a horizontal wall before viscosity dissipates the energy. An energy balance involving the kinetic energy of the fluid motion, the surface energy of the air–water interface, and the gravitational potential energy aids in the interpretation of the dynamics of the collision. We also observed the motion of a bubble rising under an oblique wall with an angle of 10°–85° to the horizontal. When the angle was less than about 55° corresponding to We