Do not know the reason for high run-time of the MFiX-SQP case

MFiX How to
#1

Hello,

I hope you are doing great.

I am trying to run a MFiX-SQP case (
sample_SQP_case.mfx (11.0 KB)

with the particle_input.dat file (particle_input.dat (80.7 KB))
However, the case is running without an error in the Ubuntu system, it is taking unusually high run-time for just 528 particles, (an estimated time in days) .
Can you please let me know from the attached files what the reason for it could be, and also how I could make it work to run faster?
I am looking forward to hearing from you soon.

Sincerely,
Sumanth Penmetcha

Installation problem for MFiX 24.1.1 and 24.2 on OSX
#2

The time step is 6E-9 s. Please try to lower the Youngs modulus to see if this helps. You should also use the grid-based des search, not the N-square.

#3

Hello,

Thank you for your response.
Can you please tell me how do I change the time step, and how does that affect the solver run time?
I am looking forward to hearing from you soon.

Sincerely,
Sumanth Penmetcha

#4

The solids time step is a function of the material properties and is computed automatically. If you lower the Young’s modulus, this will decrease the time step. It is not a linear relationship, you will have to experiment with it. The run time is directly related to the time step (number of DEM iteration equals the final time divided by the solids time step).