[kishore208]

The steady state simulation is done and obtained an residual plot. Residuals values are below 10^-6 but after that varying. Do I have to perform transient simulation or can I modify some parameters to decrease those variations here only?

Image is attached here.

https://drive.google.com/file/d/1xJk...ew?usp=sharing

[Bloerb]

Check your solution tolerance in fvSolution. You'll find something like this:

    p_rgh
    {
        solver          GAMG;
        smoother        GaussSeidel;
        tolerance       1e-06;
        relTol          0.05;
    }

Which means either solving down to a tolerance of 1e-6 or reducing it to 0.05 of the previous value. Hence once you reach the tolerance values below it are by chance a bit below 1e-6 or quite a lot. You could reduce this tolerance further if needed. This wiggling will occur however once you reach the solution threshold.