Its Mfix DEM simulation of gravity driven particle flow.
In the above image, the cyclic BC condition is applied along Y-axis.
Also gravity is applied in the Y- direction.
The particle flow is looping but some particles are seen coming out from the domain. It shouldn’t happen. The particles should only flow inside the computational domain.
How should I rectify?
Did you define a wall BC for the half-cylinder?
I have selected facets in the STL file using the vector X=−1, Y=0, Z=0, with an angle of 90degree.
Current result is as shown below:
This is for 0.06s
This is for 0.17s.
The volume fraction is shown as below
Actually for the wall including fin section, I should assign symmetry BC.
Please guide how to set the symmetry BC on that.
What do you mean by “symmetry BC”?
Symmetry boundary condition treats the right wall as if the flow and geometry are mirrored on the other side, meaning there’s no flow or heat crossing through it. This helps reduce the size of the domain we need to simulate, saving time and computational resources, while still keeping the results accurate. It’s especially useful for designs like pin fins, where the flow pattern repeats across symmetrical planes
I don’t think “symmetric boundary condition” is supported directly in MFiX, but you can set all the flow rates to zero at the BC, which should achieve the same thing.
Okay I will try with that. Also if I need to create control volume around the section view of the cylindrical fin to for the evaluation of the velocity at the tube surface. How will I create that when CVs are arranged in circular layers around the tube (CV size: 1.2 mm in radial direction, 2.5 mm in tangential direction, 7.0 mm in axial direction) ?
MFiX has some code for cylindrical coordinates, but it is deprecated and unsupported.
The best way to define these control volumes is probably to define them as STL regions. You can use procedural geometry to define these. See the procedural geometry tutorial.
