Simcenter FLOEFD Simcenter FLOEFD : number of iterations per travel
Summary
Simcenter FLOEFD performs the first convergence check upon reaching 1 travel. The term "travel" is an internal calculation terminology and from a user-standpoint can be imagined as the point of time when beginning from the defined inlet(s) a fluid particle passes the outlet(s) for the first time. The term "Iterations per 1 travel" is a calculus estimate of how much iterations Simcenter FLOEFD needs to perform to reach this first travel. Sometimes it could be of interest to manually perform such an estimate. What is the formula with which the value for the term "Iterations per 1 travel" is calculated by Simcenter FLOEFD?
Details
When dealing with particular physics, it can be noted during the run that the number of iterations per travel are very high.
Let’s restrict our investigation by stationary and incompressible (with or without cavitation).
In this case number of iterations per 1 travel will be = coefficient * POW(number of fluid AV, 1/3)
Information on the Number of fluid control volumes AV: G.Fluid , can be found in the mesher logfile *.cpt.stdout (with * being the number of the project/results directory) under the lines which reports "BRICKS":
Coefficient (the value of this coefficient can significantly change according to the simulation type and physical features taken into account for the calculation (internal, external, cavitation, combustion etc.).
Please refer to this table for some possible Coefficient values:
| Examples for possible used Coefficients | |
| Cavitation / (usually Combustion too) cases in internal flow tasks | Coefficient = 50 |
| Cavitation / (usually Combustion too) cases in external flow tasks | Coefficient = 10 |
| Other cases | Coefficient = 2 |
For transient analyses with automatic timestep the formula is following:
Iterations per 1 travel = coefficient * POW (number of bricks, 1/3)
where coefficient:
| Examples for possible used Coefficients | |
| Cavitation / (usually Combustion too) cases in internal flow tasks | Coefficient = 125 |
| Cavitation / (usually Combustion too) cases in external flow tasks | Coefficient = 25 |
| Other cases | Coefficient = 5 |
This is an update/correction of the existing technote: MG585798