OpenLB – Open Source Lattice Boltzmann Code Forums on Lattice Boltzmann Methods General Topics Pressure boundaries in multicomponent flow

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• #1783
rv88
Member

Hi,rnrnI am trying to simulate displacement of a wetting fluid by a non-wetting fluid in a simple converging geometry. I am very new to LBM, and I have been trying to understand how to implement boundary conditions.rnrnI went through Sukop’s book, but it wasn’t clear how I should implement pressure boundaries for multicomponent fluid flow. In the example codes given with OpenLB, the boundaries are bounce-back only, correct? I could not see an example of implementation of pressure boundaries.rnrnCould someone please guide me with this? I have been struggling with this problem for a while now.rnrnThanks!

#2194
mathias
Keymaster

Hi,rnrnThere is no example online. That is right. But pressure boundary conditions are implemented and work fine. You can apply them as in the cylinder2d/3d example. Mind that sum f = rho=0 will not work since u = sum vf / sum f will not be defined in that case!rnrnBest rnMathias

#2216
rv88
Member

Hi,rnrnSo my goal is to ultimately do a multicomponent simulation. I am trying to wrap my head around the Rayleigh Taylor 3D example, and ultimately implement pressure boundaries in a geometry of my own choice. In that example, when you do superGeometry.rename(0,1), what is going on? Are the voxels having 0 values renamed to 1? So we don’t have 0 value voxels anymore? The material numbers are the same as in the cylinder3d program, right?

#2218
mathias
Keymaster

Hi,rnrnsuperGeometry.rename(0,1) renames all voxels with material number 0 to number 1. Yes, you should not have 0 anymore. Yes, that is basiaclly working as in 3d.rnrnBestrnMathias

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