DEM (Fluent): collision force and total force

- May 24, 2022 at 10:01 am
  
  yyds4092
  Subscriber
  
  Hi guys When we turn on the DEM model in Fluent, we can have particle variables like total force and collision force in X Y Z direction and their magnitudes.
  In Ansys_Fluent_Users_Guide_2022R1, the total force is defined as:
  the total force (body force and volume force) acting on the DEM particle during the DEM collision
  and the collision force is defined as:
  the body force acting on the DEM particle during the DEM collision
  Therefore, I try to figure out what body force and volume force refer to and what differences they have. I looked them up in Ansys theory and users guide but I cannot find any clear definition to distinguish them. Moreover, the book called Engineering fluid mechanics by Graebel William said ''Body forces (sometimes called volume forces) '', which makes this question a little bit silly. However, I compared these two forces in my simulation and they are quite different. I am wondering if anybody could help me out?
- May 24, 2022 at 12:53 pm
  
  yyds4092
  Subscriber
  
  Hi Dr Amine I am wondering if you could give me any advice about this problem or suggest how Fluent DEM calculated these forces.
  
  Sincerely
  Yyds4092
- May 24, 2022 at 1:12 pm
  
  Amine Ben Hadj Ali
  Ansys Employee
  
  Please be patient.
  One is the Net Force and the other just accounting for the collision force.
- May 24, 2022 at 2:51 pm
  
  yyds4092
  Subscriber
  
  Dear Dr Amin Excuse me, sorry for disturbing you.
  Do you mean the total force is the sum of the forces in the equation above (including collision force) and the collision force is just the force calculated from Collision Laws? I am wondering if there is any reference I could refer to as I want to put these results in my work.
  
  Sincerely
  Yyds4092