# method for best approximation?

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 April 27, 2004, 11:52 method for best approximation? #1 Laszlo Guest   Posts: n/a 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!

 April 28, 2004, 01:48 Re: method for best approximation? #2 FJ Guest   Posts: n/a 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

 April 28, 2004, 10:22 Re: method for best approximation? #3 Laszlo Guest   Posts: n/a 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!

 April 29, 2004, 04:17 Re: method for best approximation? #5 Laszlo Guest   Posts: n/a 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.

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