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Home Forums ANSYS Fluent Beginners to Advanced level Lesson 15: Query regarding pressure based vs density based solvers

• # Lesson 15: Query regarding pressure based vs density based solvers

Posted by on October 4, 2023 at 8:41 am

Hi everyone,

I am currently finishing my assignment for lesson 15 where I try out different solvers to simulate the flow over a geometry.

The geometry I chose was a NACA2412 aerofoil and I gave the inlet flow velocity as 200 m/s.

I tried different solvers as mentioned in the lesson video such as pressure-based (coupled, SIMPLE, PISO) and density-based solvers. However, I just wanted some validation to check if my answers were correct.

My solution converged for pressure-based solvers (coupled and SIMPLE) but diverged for pressure-based PISO and density-based solvers. It would be really helpful if someone could explain why is that the case that is diverged for only PISO in the pressure-based solver and for the density-based solver.

I am attaching my residual PNG files as a reference.

replied 6 months ago 3 Members · 3 Replies
• 3 Replies
• ### aryal.bibek.biz

Member
October 4, 2023 at 5:54 pm

I have also got similar results, but how can we write it effectively and what are the reasons for it?

• ### Aditya

Member
October 5, 2023 at 10:27 am

Yes, I got similar results.

However, I am not sure why the PISO method fails to converge even though the SIMPLE and SIMPLEC converges. More puzzling is why the density-based method didn’t converge as I reckoned it should have converged for high velocities such as 200 m/s

• ### balliburak93

Member
December 11, 2023 at 7:39 pm

I have obtained the same solutions. I’m unsure why the density-based solver didn’t work for this problem. I expected achieving a converged solution using the density-based solver instead of the pressure-based solver.

After reviewing Bibek’s solutions, I have doubts about my mesh structures. While the mesh structures around the aerofoil were indeed perfect, I utilized a very coarse mesh far away from the aerofoil, and this might be why I couldn’t achieve a converged solution. The drag coefficient values in Bibek’s solution are very similar, suggesting that the solution near the aerofoil is likely converged.

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