How do I set the ISAT parameters in FLUENT?
The numerical error in the ISAT table is controlled by the ISAT Error Tolerance, which has a default value of 0.001. This value is relatively large, which allows faster convergence times. However, once the solution has converged, it is important to reduce this ISAT Error Tolerance and re-converge. This process should be repeated until the species that you are interested in modeling are unchanged. Note that as the error tolerance is decreased, the memory and time requirements to build the ISAT table will increase substantially. There is a large performance penalty in specifying an error tolerance smaller than is needed to achieve acceptable accuracy, and the error tolerance should be decreased gradually and judiciously.
1) Monitor a minor species (for example, the maximum value of a minor species at the outflow)
2) Start with a large ISAT Error tolerance (0.001)
3) Run the simulation until it converges
4) Erase the ISAT table, decrease the tolerance by a factor of 10
5) Repeat step 3
6) When the monitor is stable, you reached a good error tolerance for your chemical mechanism and operating conditions
You should set the ISAT Max. Storage to a large fraction of the available memory on your computer.