I would like to ask your help to select the best method for solving a flow problem.

There is an air channel 10mm x 2mm x 1mm and it is heated in a part of a channel. The air speed is between 0m/s and 50 m/s.

I would like to modell the effect of the heating to the velocity field and to the turbulence.

Do you think it will good approximate the real circumstances if I set the air material properties the following way: I set density as "ideal-gas" and set both viscosity and thermal conductivity as "kinetic-theory"?

What do you think which turbulence method gives the best approximation?

Thank you for your answer!

Hi,

In your case, the mesh needs to be very fine near all walls and the material property is set as a actual gas. "ideal-gas-law" is the good appoximation and the other properties should be a function of temperature or "kinetic theory" as your remarks.

I think "LES" is the best model.

Thanks

FJ

Thank you for your answer!

I will read books on turbulence soon... Maybe you know a simply answer so I put on the question.

If there is an real flow thing and I want to modell it with Fluent how do I know the best parameters for turbulence specification (at inlet velocity parametrisation)? And if I select intensity and length scale, which values gives the best approximations to the real circumstances? Could you give me some suggestions please?

Thank you in advance!

Laszlo:

answer to your question is in the online help for fluent 6.1

please read chapter 6. Boundary Conditions

Your answer was useful! Thanks! In velocity inlet part I read I shouldn't use velocity inlet with compressible flows.

At chapter 6.2.2. there is a calculation method for Turbulence Length Scale in duct flow. It was helpful too.