Learning Forum

[DaN]

Hello everybody,

I use ISAT tables for a chemistry-only simulation within a flow field in Fluent (Stiff Chemistry Solver, Finite Rate, and DPM is used).

After around 400 regular Iterations an error occurs:

______________________________________________________________

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

routine = isat_leaf_init

location = 1

message = svd failed, INFO= 29

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

ell_radii: info, n, lwork, work(1) = 29 30 9600

1050.00000000000

sv =

NaN NaN NaN NaN NaN

NaN NaN NaN NaN NaN

NaN NaN NaN NaN NaN

NaN NaN NaN NaN NaN

NaN NaN NaN NaN NaN

NaN NaN NaN NaN NaN

The fl process could not be started.

________________________________________________________________

Does somebody understand what happend? Simulation was on the way to convergence. One species has a very rapidly, artificially high, unrealistic, one way kinetic ( "direct" combustion of ethanol to CO2 and H2O by only one equation and exzessive kinetic parameters). All other reactions (some potassium chemistry) have realistic parameters and are stable without the combustion of ethanol. Everything works great until the error occurs.

Additionally, I want to save the interim result but the program is not completely controllable after the error. Saving case, data, isat table and creating contour plot does not work. Is there something I can do? The interim results are satisfying to run further simulation from. Other program features like the adjusting of the setup is still possible.

Thank you very much!

[RK]

Hello,
This error could indicate stiffness of the reaction mechanism. Try lowering the pre-exponential factor by a couple of orders of magnitude and if you have any data to validate the results, check the impact of doing so. Another suggestion would be to look at alternative reaction mechanism.