Bubble growth detachment influence BC domain size by Michael Alletto

• contributor: Michael Alletto
• affiliation: WRD MS
• contact: click here for email address
• OpenFOAM versions: v2012
• Published under: CC BY-NC-ND license (creative commons licenses)

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Bubble growth detachment influence BC domain

You can download the case files [1] here.

Introduction

In a resent OpenFOAM version (see https://www.openfoam.com/releases/openfoam-v1706/numerics.php) a new interphase advection scheme was released. It is a geometric volume of fluid method. Geometric volume of fluid method means that a geometric model for the interphase position and orientation within a cell is established and advected within a time step. One can imagine that the interphase between two fluids within a cell is described as a plane which has a given position of the plane center and orientation of the normal vector. Two different method to reconstruct this plane are currently available within interIsoFoam: isoAlpha and plicRDF. isoAlpha calculates the surface dividing the two fluids based on the α iso-value which cuts the cell according to the volume occupied by the two fluids. For details see [6,7]. plicRDF uses a piece wise linear radial distance function to compute the orientation and position of the interphase within a cell. The gradient of the distance function gives the normal of the interphase. By moving the interphase position within the cell the volume fraction of the two fluids divided by the interface can be adjusted to the α value. For details see [6]. This reconstruction method was released with OF2006 (see https://www.openfoam.com/releases/openfoam-v2006/solver-and-physics.php).

In a resent paper [2] performed an extensive comparison and validation of the two reconstruction methods of interIsoFoam. They compared interIsoFoam with interFoam and another volume of fluid code (Basilisk). The main findings of the paper were that: (i) plicRDF causes the smallest parasitic currents in a static bubble, (ii) regarding a rising 2D bubble plicRDF delivers slightly better results than MULES with a bit smaller computational times and (iii) plicRDF was the only OpenFOAM version capable to predict the spiraling movement on a coarse grid of a 3D rising bubble. Note that the test cases of the paper can be downloaded here: https://wiki.openfoam.com/Collection_by_authors\#Lionel_Gamet.

Inspired by the novelty of the plicRDF interface reconstruction method and the promising results of [2], the purpose of this tutorial is to analyze the solver interIsoFoam with the plicRDF reconstruction method a bit more in detail. For this purpose the experiment described in [1] is taken as reference. [1] measured the shape of a axial symmetric air bubble exiting a circular orifice. The orifice was submerged by a liquid. This kind of test case is often used as preliminary test case for solvers which are meant to be used later to simulate boiling (see [3,4]).

In this first tutorial of a series we will analyze the influence of the boundary conditions and domain size on the flow and detachment time of a rising bubble. The next tutorials will have a look at the influence of the grid size, time step size, number of inner and outer iterations, settings of the parameter influencing the interphase advection scheme and finally also the way the curvature of the interphase is computed.

References

[1] A Albadawi, DB Donoghue, AJ Robinson, DB Murray, and YMC De- lauré. On the analysis of bubble growth and detachment at low capillary and bond numbers using volume of fluid and level set methods. Chemical Engineering Science, 90:77–91, 2013.

[2] Lionel Gamet, Marco Scala, Johan Roenby, Henning Scheufler, and Jean-Lou Pierson. Validation of volume-of-fluid openfoam R isoad- vector solvers using single bubble benchmarks. Computers & Fluids, 213:104722, 2020.

[3] Anastasios Georgoulas, Manolia Andredaki, and Marco Marengo. An enhanced vof method coupled with heat transfer and phase change to characterise bubble detachment in saturated pool boiling. Energies, 10(3):272, 2017.

[4] Anastasios Georgoulas, P Koukouvinis, Manolis Gavaises, and Marco Marengo. Numerical investigation of quasi-static bubble growth and de- tachment from submerged orifices in isothermal liquid pools: The effect of varying fluid properties and gravity levels. International Journal of Multiphase Flow, 74:59–78, 2015.

[5] Johan Roenby, Henrik Bredmose, and Hrvoje Jasak. A computational method for sharp interface advection. Royal Society open science, 3(11):160405, 2016.

[6] Henning Scheufler and Johan Roenby. Accurate and efficient surface reconstruction from volume fraction data on general meshes. Journal of computational physics, 383:1–23, 2019.

[7] Henning Scheufler and Johan Roenby. Twophaseflow: An openfoam based framework for development of two phase flow solvers. arXiv preprint arXiv:2103.00870, 2021.