boundary conditions for SCMP Model

Palabos General
#1

Hi,

I have some problems with boundary condition in Palabos. Only periodic and bounceback boundary condition works fine with the SCMP Model, but the others like velocity or outflow boundaries produce mistakes. It is possible to use a flow boundaries with this model?

Thanks in advance

#2

Hi,

You’re right: except for bounce-back and periodicity, the boundary conditions in Palabos are made for the “incompressible, single-component Navier-Stokes” models. This seems to be a delicate topic, not only because implementing an adequate boundary conditions in Palabos requires some work, but also because, to my knowledge, the literature on how to implement boundary conditions with the Shan/Chen model is very vague. Nevertheless, all of this is part of the “under development” section of the Palabos project.

In the meantime you might find that you will get a stable (if not very accurate) simulation by imposing an equilibrium distribution on the boundaries (in the two-component model, you need to do this for both fluids, and it is your responsibility to come up with a reasonable value for the density). This can be done with the “createEquilibriumBoundaryConditoinXD” boundary condition, or even more brutally, by manually imposing the equilibrium with a given velocity and density value after each iteration through a “initializeAtEquilibrium” command applied to the boundary nodes.

#3

Hi,

I am trying to run multiphase flow simulation in porous media. I am injecting one phase to displace another one.
I started with rayleighTaylor and then, I tried to change boundary conditions.
In my simulation, I tried using inlet and outlet boundary conditions as:

Box3D inlet (0,0,      0,ny-1, 0,nz-1);
boundaryCondition->addPressureBoundary0N(inlet, heavyFluid);
setBoundaryDensity(heavyFluid, inlet, 1.);




Box3D outlet(nx-1,nx-1, 0,ny-1, 0,nz-1);
boundaryCondition->addPressureBoundary0P(outlet, lightFluid);
setBoundaryDensity(lightFluid, outlet, 0.1);

but this gives me Nan answer!
Could anybody help me with this?

Moreover, I have a question about rayleighTaylor problem.
For setup of rayleighTaylor problem, we define two regions with different densities.
What these densities really mean? Are they physical densities?

#4

Hi ali805509,

Have you solved your problem? Similarly, I’m using SC to simulate displacement in a channel. I tried ZOU/HE and extrapolation boundary condition on the inlet, but it does not seem to work well.

Could anyone give some suggestions on this?

Much appreciate,
Ed

#5

Hello Edward,

Almost all the displacement simulations that I have seen in the literature used Periodic Boundary Condition.
I guess you should change the setup of your problems to fit to that!

Ali