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Individual DEM - Fluid interaction
  • Dear Users/Developers

    I’m trying to drop chunk of DEM particles (let’s say sand) into the water. During reading the manual and source code I came up with couple of questions and suggestions as follow:

    1- What’s the best way to import individual DEM particles into the scene? Floating object might be a solution but problem is that the position of the particles in the floating objects are restricted by fixed spacing which is against what I want to do (individual DEM particles that can move independently).

    2- Is there any description/manual about structure of bi4 input files which holds information about initial particles positions and etc.? Knowing the structure of input file might help me to somehow manipulate it for my benefit.

    3- Suggestion: adding new type of particles (let’s say CODE_TYPE_DEM) to the program might give more freedom to the users that want to import individual DEM particles to the model without using the floating objects.

    any suggestions or comments!?

  • Hey Roozbeh,

    essentially answering all of your questions at the same time, the code as it stands is not prepared for what you want to do. The fundamental idea of the current model, even at a conceptual level, is that the a rigid body is much larger than the fluid discretization. A factor of 100 over a significant direction is usually where you start getting good results. You see the problem if you want to model sand...

    I would advise you and all interested to take a look into the works of Robinson et al 2013 ( for example.

    You are welcome to introduce a new type of particle and make the code changes you need. Use our GitHub, clone the repository and make a pull when you get a stable implementation so we can include it in the main code!


  • Recardo,

    thanks a lot for your response. I think I understand what you mean by size factor.