The extended collision stencil uses particles in neighboring cells to calculate the collision probability. The current model only uses particles in the current cell to calculate the collision frequency, where in this case particles in the closest N cells to the current particle location (where N is set by the user) are also allowed to collide.

The model should be used when the mesh is very fine and the spray is represented by relatively few particles per cell. Using a larger sample volume improves the statistics of the collision calculation. Note that the cost for calculating collision depends on the square of n, where n is the number of particles in the sampled volume, so increasing the number of cells beyond 3 or 4 can increase the computation time significantly.

To use this model (after enabling beta feature access, described in Introduction ), enter the following text command:

define → models → dpm → spray-model → droplet-collision? and enter the following responses to the commands:

  Spray collision model [yes]
  Spray collision model type [0-O’Rourke, 1-Stencil, 2-NTC]  [0] 1 
  Spray collision stencil size  [1]
   Spray collision event type [0-All, 1-Eff.Diam, 2-Impinging]  [0]