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Murthy March 30, 2002 19:35

Adiabatic condition at inlet
Hello, This may look strange but I want to model an adiabatic inlet condition.The boundary type is velocity inlet and I am trying set the inlet as adiabatic.Any suggestion help would be of great help. Thanks in advance Murthy

chiseung March 31, 2002 08:42

Re: Adiabatic condition at inlet
How about using the "interpolate" in solver.

By solving the momentum equation and energy equation separately, you can give the adiabatic boundary condition at your inlet.

P.S. If the energy trasport in your system is strongly affected by flow field, above treatment would be improper.

Murthy March 31, 2002 16:12

Re: Adiabatic condition at inlet
Could you please expound on "interpolate" and how we can then use this to define the boundary condition. I am using Fluent 5.5 and using the segregated solver for the solution process. THanks in advance, Murthy

chiseung March 31, 2002 21:20

Re: Adiabatic condition at inlet
The function "Interpolate" can export your field variables(velocity, scalar, pressure, k value, epsilon value. etc.) as a file. This "interpolate" function is used frequently when field initialization is required. Compared to "profile" file, this is used in whole computational domain or part of volume you have designated.

Though I just recommended the "interpolate" function, I'm not sure that the use of "interpolate" is proper to your system. The reason is I don't know your system exactly.

Murthy April 1, 2002 13:33

Adiabatic condition at inlet
Hello, I just looked at the interpolate function in the file menu,but I have not been able to get further info. I was thinking if it were possible to implement the same using UDF's.I tried the same but at the face the gradient of temperature cannot exist hence ,I want to get some more ideas regarding implementing this using UDF and UDS and thanks for the reply. Murthy

chiseung April 2, 2002 08:13

Re: Adiabatic condition at inlet
Follow these sequences but this is only my opinion.

(1) Set the solver to solve only momentum equation with the option "energy" is turned on(besides, turn down energy equation in "solve->control" menu).

(2) Solve the momentum equation with above solver settings.

(3) If the solutions are converged, change your inlet boundary type to "wall" boundary in boundary condition panel and give the adiabatic b.c. at the changed inlet boundary.

(4) Turn on flow equation and turbulence(if you solve this) and turn down energy equation in "solve->control" menu).

This is, I think, numerically describing your question but I'm not sure this is physically meaningful. It's up to you.

Robin April 2, 2002 13:42

Re: Adiabatic condition at inlet
Hi Murthy,

Just what do you mean by adiabatic? Your inlet should be advecting fluid at some temperature, are you saying you do not want to specify the temperature at your inlet?


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