[Solved] multiphaseInterFoam, velocity appears from nowhere
 

Hello,

I have only few experience on OpenFoam and I have a problem that I can not solve...

I have a cylinder filled with 2 different fluids with different density, the fluid with the lower density is on the upper part.
Attachment 25256
Attachment 25260
(the mesh is quite inaccurate, but even if I do it more precisely, this problem still appears).

The cylinder is closed (every boundary condition = wall )
Every initial condition (internal/boundary conditions, p_rgh, U, alphas) are set up to uniform0 or ZeroGradient, and there is no initial velocity.
Attachment 25261
Attachment 25258
So, I was expecting that the system remains stable in the time, I mean always egal to the initial configuration.


But, after lauching the simulation, a velocity appears inside the cylinder from nowhere, for example here, after 200s computation, we have a max velocity of 0.03 m/s around the interface of the 2 fluids.
Attachment 25257

I don't know where is my mistake... Can someone helps me to solve this ?

Thank you !

Hi Leopold,

these are the infamous "parasitic currents" (a.k.a. "spurious velocities") that appear due to the kind of VOF function used in OpenFOAM.

There are lots of information about them in the forum, you should take some time to learn about them, but in short, no one has been able to make them disappear (yet).

Best,

Pablo

Ok !
Thank you very much Pablo, as you had suggested, I will look for information about this problem, as I can now put a name on it !

Leo