Problem: I have a combustion solution where my species monitors are exhibiting wide, saw tooth swings, but there is no corresponding fluctuation in global temperature. My reactions are implemented with UDF source terms. The time step is small and residuals generally look quite good. What might be causing this?
Tagged: 17.2, Convergence Problems, fluent, fluid-dynamics, General, Species/Reactions
January 25, 2023 at 7:17 amFAQParticipant
In this case, it is likely that the monitor locations are the culprit. If monitors are located are near a wall, and there is no near-wall resolution, for instance, the monitors will exhibit fluctuation as follows: UDF implemented reaction rates may be zero at the wall, so monitored values of species concentrations just off the wall will wander between reacted and unreacted extrema. The solution is to refine the near-wall mesh and locate the monitors further into the boundary layer
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