Learning Forum

[smithamohanam]

I would like to request your technical guidance regarding the following issues:

1. Creating a Soil Sample with Given Porosity / Void Ratio using ROCKY DEM:
   I am unable to find an option within ROCKY DEM to directly define or control the porosity (or void ratio) of the generated soil assembly. Could you please advise whether there is a feature or workflow in ROCKY that allows users to create a particle bed with target porosity?
   If not, is there a recommended method—such as particle size control, insertion density, compaction, or pre-conditioning—that can help generate a soil sample with a specified porosity?

2. Change in Sample Height and Porosity After Gravity Activation:
   After generating the particle assembly, when I activate gravity to settle the particles, both the height of the sample and the porosity change significantly from the intended values.

   • Is there a way to fix the dimensions or lock the porosity after sample generation?

   • How can I ensure that the porosity remains stable after gravitational settling?

3. Running the Model Without Gravity:
   The simulation does not run properly unless gravity is activated. Could you please clarify whether ROCKY requires gravity for CFD–DEM two-way coupling, or if there is an alternative method to stabilize the particle bed without changing its porosity?

I would greatly appreciate any documentation, workflow steps, or best-practice guidelines related to preparing porous soil samples in ROCKY DEM for CFD coupling.

Thank you very much for your time and support. I look forward to your guidance.