Learning Forum

[P_Heng]

Hello everyone,

I want you to recommend to choose the option in Ansys Fluent Setup for Bouyancy. And put it in the case of static and dynamic. The governing equation is sent below.

[DrAmine]

Do you outlet? If yes what is outside?

[P_Heng]

I will send you the boundary condition picture.

My regards Pho Prosheng.

[P_Heng]

[P_Heng]

Hello everyone if I run the calculation in Ansys Fluent, How can I know my process of running the calculation is Bouyancy or density?

IÔÇÖm sorry that my explanation is not good enough. I hope you understand what I mean.

I send the picture again.

[Rob]

I can't read that, where (and what) are the boundaries? Given your other thread, make sure you have enough mesh to see any flow profiles: you want 10 cells minimum across the channel.

[P_Heng]

My prof said it doesnÔÇÖt matter how many cells do I use for the mesh, the flow should parallel the shape of domain.

Now, I can make the flow vectors parallel the shape of domain by use Presto for pressure (in method)

This picture is boundary condition .
if I run the calculation in Ansys Fluent, How can I know my process of running the calculation is Bouyancy or density?

My regards Pho Prosheng.

[Rob]

I can't see what boundaries you have set, and are they flow, hot/cold walls etc. Buoyancy is calculated assuming gravity is on, and the material density can vary: otherwise the buoyancy term is zero. With a near zero velocity and coarse mesh convergence may be poor, and therefore results may be misleading. Refine the mesh, converge the solution and see how the result changes.

[DrAmine]

:) PRESTO! is recommended for buyoancy flows and to avoid the velocity issues you saw nevertheless again your mesh is not adequate.

[P_Heng]

I found the 7.3.1. Bouyancy-Driven Flows and Natural Convection in ANSYS Fluent User Guide Manual. It tells the process of Buoyance-Driven Flows.

Your answer is right. I just change pressure from second order to PRESTO! , Now my flow is good and parallel the shape of the domain.

Thank you.

My regards,
Pho Prosheng.

[P_Heng]

and
Thank you for your response. You help me a lot.

My regards Pho Prosheng.

[DrAmine]

Welcome!

[P_Heng]

:) :)

[Rob]

You're welcome. Just remember,and I are always right, unless we contradict each other.

[P_Heng]

Yes, sir. Thank you. :)

My regards P. Heng.