Learning Forum

[dhaya400]

Hi,

I am running a transient flow simulation in Ansys Fluent. I have been running the simulation for 10 cycles to get convergence.

After that, I am enabling passive scalar transport to know the concentration of scalar at different outlets.

My question: How many cycles I have to run the simulation, after enabling passive scalar model to get converged solution?

with regards,

DK

[Karthik Remella]

Hello When you say cycles, are you referring to iterations or time-steps? If you are referring to iterations per time-step, you may want to make sure that your residuals go down by at least 3 orders of magnitude. The actual number depends on the choice of time-step, the velocity scales, and the mesh size.
Karthik

[dhaya400]

Hi
Here the cycle refers to input sinusoidal wave for a period of 1s. So 10 cycles refers to total time of 10s.
Would you please clarify now?
with regards DK

[Rob]

If it's a pulse it's until not much is coming out. If the scalar is always on it's until the result is showing a "constant" value or cycle. You'll have an idea of the flow residence time, so it's usually a function of a few times that.