Learning Forum

[DaN]

Hello everyone,

I simulate gas-phase-reactions in a flow field within a tube using Fluent, DPM (with UDF for absorption) and chemkin import.

The simulation is apparently on its way to convergence, but during the iterations with this message is written:

********** ISAT_ABORT **************

routine = phi2y

location = 1

message = non-positive species sum

****** END ISAT_ABORT **************

The iterations take much more time .

How can I indefinite the cause of this? I guess it is about some insufficient thermodynamic properties.

Thank you for your help.

[RK]

Hello,
Probably the time step is too large for the chemical kinetics. Can you reduce it by 2 or 3 orders of magnitude and try again?
If the issue still persists after lowering the time step, I would assume the issue is with the ISAT table. You can back track to a point before the error occurred, clear the ISAT table and continue with calculation.