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I'm sorry, but DEM is not for fluid simulation. It's used to simulate granular materials by default. Also the hopper discharge that is shown does not contain an

I'm sorry, but DEM is not for fluid simulation. It's used to simulate granular materials by default. Also the hopper discharge that is shown does not contain any fluid. The fluid is usually modeled using a different tool (e.g. using the finite volume method) which is then coupled to the particles.

szvsw 2y ago
Okay, fair, I was using fluid loosely (and inaccurately) to mean both granular and fluid behavior. But there’s nothing inherently incompatible between fluid dynamics and the discrete element method as far as I am aware, just like there is nothing inherently incompatible with solids. Sure SPH or LBM or FVM are the more traditional choices for fluids and computationally more tractable in most cases, but they aren’t necessarily “more right.” Awesome paper on how powerful particle based methods can be: https://www.sciencedirect.com/science/article/pii/S1877750323002582 https://www.sciencedirect.com/science/article/pii/S187775032... And a fun image of a DEM solid model of fracture: http://www.cba.mit.edu/media/DEM/index.html http://www.cba.mit.edu/media/DEM/index.html
- Azrael3000 2y ago
  No worries. I would still consider these methods to be very different from each other. SPH, FVM and so on are methods to discretize continuum equations. If you have a continuum equation that describes your granular material you can use them and DEM kind of interchangeably. But often times such continuum equations do not exist for granular media or they break down in certain flow regimes. DEM on the other hand is not based on the continuum representation. Instead it is based on interaction forces that originate from particles being close by. While it might be possible to link these two, afaik nobody has done this, but I'm no longer active in the field.
  - szvsw 2y ago
    Take a look at the paper I linked, specifically section 4, which illustrates finding force laws to match the desired dynamics of a real physical material (in this case, Delrin, including elastic and plastic deformation. I guarantee you will like this paper!

szvsw 2y ago

Okay, fair, I was using fluid loosely (and inaccurately) to mean both granular and fluid behavior. But there’s nothing inherently incompatible between fluid dynamics and the discrete element method as far as I am aware, just like there is nothing inherently incompatible with solids. Sure SPH or LBM or FVM are the more traditional choices for fluids and computationally more tractable in most cases, but they aren’t necessarily “more right.” Awesome paper on how powerful particle based methods can be: https://www.sciencedirect.com/science/article/pii/S1877750323002582 https://www.sciencedirect.com/science/article/pii/S187775032... And a fun image of a DEM solid model of fracture: http://www.cba.mit.edu/media/DEM/index.html http://www.cba.mit.edu/media/DEM/index.html

Azrael3000 2y ago
No worries. I would still consider these methods to be very different from each other. SPH, FVM and so on are methods to discretize continuum equations. If you have a continuum equation that describes your granular material you can use them and DEM kind of interchangeably. But often times such continuum equations do not exist for granular media or they break down in certain flow regimes. DEM on the other hand is not based on the continuum representation. Instead it is based on interaction forces that originate from particles being close by. While it might be possible to link these two, afaik nobody has done this, but I'm no longer active in the field.
- szvsw 2y ago
  Take a look at the paper I linked, specifically section 4, which illustrates finding force laws to match the desired dynamics of a real physical material (in this case, Delrin, including elastic and plastic deformation. I guarantee you will like this paper!