Fluids

Fluids

DEM Collisions

    • Vicky
      Subscriber

      Hello,

      I am working on a horizontal pipe with air and solid particles; I intend to use a four-way coupled (gas-solid, solid-gas, particle-wall, particle-particle) Eulerian-Lagrangian under the DPM option.

      For the collisions, I want to use the DEM collision model. When I open the DEM option, the Collision Partners option appears by default:
      DEM-aluminum > dem-aluminum - dem-anthracite
      DEM-anthracite > dem anthracite - aluminum
      I must assume that I must fill both options with the same data since they reflect the same thing, right? (the collision of the particles with the wall of the pipe)

      Or is there a difference between those two options? 

       

      And how are there related to the wall boundary conditions? (in the option 'DEM Collision Partner')

       

      On the other hand, a number of parameters have to be specified, coefficient of restitution and friction coefficients (mu_stick, mu_glide and mu_limit) and characteristic velocities (v_glide, v_limit and slope_limit). How can I determine those parameters?

      Please could you give a reference to determine these parameters? I only found some information in Fluent’s theory or user’s guide.

      Thank you very much.

    • Rob
      Ansys Employee

      That's the same collision twice.  You need one pair for particle & wall and a second pair for particle & particle. There may be a little trial and error, or my test case is corrupt due to being built in Fluent v6

      To be honest, DEM in Fluent will cost you an awful lot of time because of the time steps needed to resolve the collisions. I'd favour Ansys Rocky coupled to Fluent, pure DPM or Eulerian over Fluent's DEM depending on need, particle loading and software availability. 

      The other properties are based on how the collisions behave, so may require experimental data. 

    • Vicky
      Subscriber

      Hello Rob, thank you very much for your answer; I only have the question if I should enter the information twice (for the same collision)?

      On the other hand, Could you please recommend a tutorial to learn how to use the Rocky software? 

      Thank you.

    • Rob
      Ansys Employee

      If you've managed to get the same collision twice delete it: I did say there may be some tinkering. 

      Ansys Rocky tutorials are on the Ansys Learning Hub, or direct from ESSS. At present it's not part of the Student bundle and I'm unsure whether it's in the Teaching/Research bundle. 

       

       

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