scholarly journals Modeling Acoustic Cavitation Using a Pressure-Based Algorithm for Polytropic Fluids

Fluids ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 69 ◽  
Author(s):  
Fabian Denner ◽  
Fabien Evrard ◽  
Berend van Wachem
Keyword(s):  
Finite Volume ◽  
Acoustic Waves ◽  
Bubble Dynamics ◽  
Acoustic Cavitation ◽  
Test Cases ◽  
Linear System Of Equations ◽  
Finite Volume Discretization ◽  
Liquid Systems ◽  
Confined Domains ◽  
Fully Coupled

A fully coupled pressure-based algorithm and finite-volume framework for the simulation of the acoustic cavitation of bubbles in polytropic gas-liquid systems is proposed. The algorithm is based on a conservative finite-volume discretization with collocated variable arrangement, in which the discretized governing equations are solved in a single linear system of equations for pressure and velocity. Density is described by the polytropic Noble-Abel stiffened-gas model and the interface between the interacting bulk phases is captured by a state-of-the-art algebraic Volume-of-Fluid (VOF) method. The new numerical algorithm is validated using representative test-cases of the interaction of acoustic waves with the gas-liquid interface as well as pressure-driven bubble dynamics in infinite and confined domains, showing excellent agreement of the results obtained with the proposed algorithm compared to linear acoustic theory, the Gilmore model and high-fidelity experiments.

A Condition Monitoring for Collapsing Bubble Mechanism for Sonoluminescence and Sonochemistry

2015 ◽  
Vol 7 (2) ◽  
Author(s):  
Ali Alhelfi ◽  
Bengt Sundén
Keyword(s):  
Acoustic Waves ◽  
Bubble Dynamics ◽  
Stokes Equations ◽  
Current Model ◽  
Computation Time ◽  
Acoustic Cavitation ◽  
Full Potential ◽  
Bubble Oscillation ◽  
Cavitation Phenomenon ◽  
Wide Range

The acoustic cavitation phenomenon is a source of energy for a wide range of applications such as sonoluminescence and sonochemistry. The behavior of a single bubble in liquids is an essential study for acoustic cavitation. The bubbles react with the pressure forces in liquids and reveal their full potential when periodically driven by acoustic waves. As a result of extreme compression of the bubble oscillation in an acoustic field, the bubble produces a very high pressure and temperature during collapse. The temperature may increase many thousands of Kelvin, and the pressure may approach up to hundreds of bar. Subsequently, short flashes can be emitted (sonoluminescence) and the high local temperatures and pressures induce chemical reactions under extreme conditions (sonochemistry). Different models have been presented to describe the bubble dynamics in acoustic cavitation. These studies are done through full numerical simulation of the compressible Navier–Stokes equations. This task is very complex and consumes much computation time. Several features of the cavitation fields remain unexplained. In the current model, all hydrodynamics forces acting on the bubble are considered in the typical solution. Bubble oscillation and its characteristics under the action of a sound wave are presented in order to improve and give a more comprehensive understanding of the phenomenon, which is considered to have a significant role in different areas of science and technology.

scholarly journals Extending the global-direction stencil with “face-area-weighted centroid” to unstructured finite volume discretization from integral form

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Lingfa Kong ◽  
Yidao Dong ◽  
Wei Liu ◽  
Huaibao Zhang
Keyword(s):  
Convergence Rate ◽  
Finite Volume ◽  
Differential Form ◽  
Integral Form ◽  
Finite Volume Methods ◽  
Reconstruction Method ◽  
Computational Accuracy ◽  
Face Area ◽  
Finite Volume Discretization ◽  
Skewness Reduction

AbstractAccuracy of unstructured finite volume discretization is greatly influenced by the gradient reconstruction. For the commonly used k-exact reconstruction method, the cell centroid is always chosen as the reference point to formulate the reconstructed function. But in some practical problems, such as the boundary layer, cells in this area are always set with high aspect ratio to improve the local field resolution, and if geometric centroid is still utilized for the spatial discretization, the severe grid skewness cannot be avoided, which is adverse to the numerical performance of unstructured finite volume solver. In previous work [Kong, et al. Chin Phys B 29(10):100203, 2020], we explored a novel global-direction stencil and combined it with the face-area-weighted centroid on unstructured finite volume methods from differential form to realize the skewness reduction and a better reflection of flow anisotropy. Greatly inspired by the differential form, in this research, we demonstrate that it is also feasible to extend this novel method to the unstructured finite volume discretization from integral form on both second and third-order finite volume solver. Numerical examples governed by linear convective, Euler and Laplacian equations are utilized to examine the correctness as well as effectiveness of this extension. Compared with traditional vertex-neighbor and face-neighbor stencils based on the geometric centroid, the grid skewness is almost eliminated and computational accuracy as well as convergence rate is greatly improved by the global-direction stencil with face-area-weighted centroid. As a result, on unstructured finite volume discretization from integral form, the method also has superiorities on both computational accuracy and convergence rate.

Sloshing in Rectangular and Cylindrical Tanks

2002 ◽  
Vol 46 (03) ◽  
pp. 186-200 ◽  
Author(s):  
Pierre C. Sames ◽  
Delphine Marcouly ◽  
Thomas E. Schellin
Keyword(s):  
Free Surface ◽  
Finite Volume ◽  
Temporal Evolution ◽  
Numerical Study ◽  
Computational Method ◽  
Test Cases ◽  
Grid Refinement ◽  
Cylindrical Tank ◽  
Excitation Period ◽  
Cylindrical Tanks

To validate an existing finite volume computational method, featuring a novel scheme to capture the temporal evolution of the free surface, fluid motions in partially filled tanks were simulated. The purpose was to compare computational and experimental results for test cases where measurements were available. Investigations comprised sloshing in a rectangular tank with a baffle at 60% filling level and in a cylindrical tank at 50% filling level. The numerical study started with examining effects of systematic grid refinement and concluded with examining effects of three-dimensionality and effects of variation of excitation period and amplitude. Predicted time traces of pressures and forces compared favorably with measurements.

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