How to increase inlet velocity in a MFiX-DEM simulation with MFiX-24.1?

Hi developers,
I am tring to simulate a CFD-DEM case with MFiX-24.1 and I want the gas velocity change with time. I have checked the similar work of others on the forum before asking you here. However, I still encounter some problems.

I prepared the usr1.f file and put it in the same folder as the .mfix file, and it was built successfully on my desktop (Windows 11). But the udf just didn’t work, bacause I monitor the outlet gas velocity and I found it kept the same with time.

And I have another question here, since I am running the simulation on my Windows desktop for a test case, and further, I will run on a Linux HPC with MPI. I wonder is there some difference between two platforms when I write the usr1.f file.

Thanks a lot !

usr1.f (2.4 KB)
fluid_bed_dem_2d.mfx (7.8 KB)

For MFIX-24.1 you do not need to use the usf but can define the ramp directly under the inlet boundary condition.

Thanks for your kind reply! It is very useful for me!

that is what I thought when asking @jeff.dietiker to add this. I am glad