Mesh sensitivity for fixed (TFM) beds

MFiX How to
#1

Dear community,

I am performing some fixed bed simulations using TFM by disabling the momentum equation of the solids phase. This to prevent their motion in case u>umf and to increase simulation speed.
I am finding real issues with the mesh sensitivity, I’m using particles of 1 mm diameter and the mesh I’m testing now is of 1 mm in the direction of the flow (plug flow - 1D), because with 2.5 mm I haven’t reached the mesh independence state, indeed, I’m finding considerable differences between the different meshes I’ve tested (from 10 mm to 1 mm so far). This seems a total nonsense to me from a TFM perspective, to use a mesh of the same size than the particles.

Does anyone have experience on this?

Thanks

#2

I do not have any experience really but for as long as your Ug<Umf, I do not see the need for disabling the momentum equation. Have you tried to run the simulations with momentum equation turned on?