Setting Solver Parameters and Stopping Criteria

The Multiple Size-Group solver default under-relaxation settings give reliable convergence in one-speed cases. However, cases that have a high particle concentration, or multi-speed cases where each size-group can travel in a different direction, require additional relaxation. In this simulation, values of 0.7 and 0.5 respectively are appropriate.

The under-relaxation factors for the other solvers are set as high as possible. In this case, most settings are lower than the default values.

To set the solver parameters and stopping criteria:

  1. Edit the Solvers node and set the following properties:
    Node Property Setting
    Segregated EMP Flow > Phase Coupled Velocity Implicit Under-Relaxation Factor 0.8
    Explicit Under-Relaxation Factor 0.4
    Segregated EMP Flow > Pressure Under-Relaxation Factor 0.1
    Volume Fraction Implicit Under-Relaxation Factor 0.8
    Explicit Under-Relaxation Factor 0.2
    Multiple Size-Group Implicit Under-Relaxation Factor 0.7
    Explicit Under-Relaxation Factor 0.5
    AMG Linear Solver Convergence Tolerance 0.001
    Cycle Type V Cycle


This simulation requires about 1500 iterations to achieve reasonable convergence.
  1. Edit the Stopping Criteria node and set the following properties:
    Node Property Setting
    Maximum Steps Enabled Activated
    Maximum Steps 1500
  2. Save the simulation.