Solve divergence for the PISO algorithm in unsteady solution (ANSYS FLUENT)
hello to all
I'm doing an unsteady simulation for the delta wing in the Fluent. I compared PISO and SIMPLE-C algorithms in this investigation. Since Fluent offers to use the PISO algorithm for transient flow but the solution was diverging for this algorithm and the system gave a floating-point error. In contrast, the solution was convergent in the SIMPLE-C method. I don't know why the PISO algorithm is inefficient at this unsteady project (Contrary to Fluent's suggestion). Time step adjusted about 0.0002 s. I used to see the same question in a different place but I did not get the right answer.
Also, when I used Extrapolate Variables the solve was diverging for both algorithms.
please guide me.