[JLoenartz]

Hallo everyone,

this is my first post in this forum and I hope I am doing it right.

I am currently working on a simulation using simpleFoam, in later studies I want to add particle transport.
I attached a simple and reduced sketch of the problem.

I am simulating an extraction system to filter particles out of the air. In this system, there are two outlets, through which the air is sucked out of the system. On one side (in the sketch on the left side) the machine is open to the environment and there is a gap over the length of the machine, through which air can enter into the system.

So basically it is the opposite situation of the standard velocity-inlet/pressure-outlet situation. I know the velocity on the outlet-patches and the pressure on the inlet-patch.


And basically that's what I set my bc's to:


Here the bc's for U

 outflow_1
    {
        type        fixedValue;
        value       uniform (0 6.485 0);
    }
    
    outflow_2
    {
        type        fixedValue;
        value       uniform (0 1.8 -2.801);
    }


    inlet_big
    {
        type        outletInlet;
        value       $internalField;
        outletValue uniform (0 0 0);
    }

    inlet_gap
    {
        type        outletInlet;
        value       $internalField;
        outletValue uniform (0 0 0);
    }

and here the bc's for p

"outflow.*"
    {
        type            zeroGradient;
    }
    
   
    inlet_big
    {
        type            fixedValue;
        value           uniform 0;
    }

    inlet_gap
    {
        type            fixedValue;
        value           uniform 0;
    }

the study ran to completion, but the results seem physically implausible, especially on the inlet_gap patch. It shows high velocities in one corner, and the rest is 0 (outletValue of the outletInlet bc)

Since I never had a problem of this kind before, where the velocity on the outlet-patches are known and the openings to the environment are the inlet-patches, I wanted to ask if anyone can recommend the right boundary conditions for these kind of problems, it would help me a lot.



Thanks in advance and I hope to be able to return the favor one day,
Jonas