Setting Solver Parameters and Stopping Criteria
Set the appropriate solver parameters and stopping criteria for the simulation.
The under-relaxation factors for the solvers are decreased to help the solution converge. These relaxation factors have not been tuned for best performance in this one particular case. Rather, they have been chosen to also allow converged solutions to be obtained for many of the test conditions reported in Bartolemei (1982) ([972]).
To set the solver parameters and stopping criteria:
-
Edit the
Solvers node and set the following properties:
Node Property Setting Implicit Under-Relaxation Factor 0.5 Under-Relaxation Factor 0.1 Volume Fraction Implicit Under-Relaxation Factor 0.1 S-gamma Implicit Under-Relaxation Factor 0.1 Segregated Energy Fluid Under-Relaxation Factor 0.5 K-Epsilon Turbulence Under-Relaxation Factor 0.5 The Sauter Mean Diameter is predicted from the ratio of S2 and volume fraction. Therefore the Volume Fraction and S-gamma solvers are given the same relaxation factors to ensure that these two fields are progressed together.
In addition to solver relaxation factors, there are further relaxation factors that are associated with some specific model terms.
-
Edit the
node and set the following properties:
Node Property Setting Boiling Mass Transfer Rate Relaxation Factor 0.1 Wall Boiling Relaxation Factor 0.1 Wall Dryout Area Fraction
Bubbly Layer Relaxation Factor 0.5 -
Edit the
Stopping Criteria node and set the following properties:
Node Property Setting Maximum Steps Enabled Activated Maximum Steps 3000 - Save the simulation.