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Old   September 2, 2004, 04:18
Default Transient Boundary Conditions
  #1
James Date
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Hi guys,

A simple question:

Which is the best way to apply a transient boundary condition i.e. time varying inflow condition using data from a look up table, rather than a user defined function f(t) in the CCL language?

I've used the CCL language to apply transient boundary conditions that are easily described by a mathematical function dependant on time, however, I was wondering what approach is best for boundary condition which aren't easily described by mathematical functions.

In CFX-4.3 I used to use a user FORTRAN routine called USERBCS, is a similar approach taken in CFX-5.7?

Regards James

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Old   September 2, 2004, 06:29
Default Re: Transient Boundary Conditions
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test
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Hi, You need not create use user-subroutine.. you can use the 1D or cloud interpolation function where in you can import the file containing the data of points Time vs variable. (the data can be either tab/comma seperated. one set of data on one line in notepad/wordpad) remember unlike in CFX-4 you need not have the first line representing the number of data points.

Go to Create--> Library objects--> User Functions in the pre window (define a name to the funtion being created).

Suppose you create a function called as myfunction, which specifies temperature as a funtion of time. The argument of the function would be time while the result would be temprature. Give the units the argument and result enclosed in square brackets.

you can eiher enter the data one by one or right click in the data box and click on import and import the file.

In the boundary condition tab, you can refer to this function as

myfunction(t)

where t refers to time
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Old   September 2, 2004, 08:11
Default Re: Transient Boundary Conditions
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James Date
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Hi

Thanks ever so much for your help, it seems pretty simple to set up, we'll compared with what you used to have to do in CFX-4.3.

Thanks again.

James
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Old   September 8, 2004, 16:52
Default Re: Transient Boundary Conditions
  #4
Robin
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Hi James,

You could also create your own user defined CEL function, written in Fortran.

Regards, Robin
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Old   September 13, 2004, 03:20
Default Re: Transient Boundary Conditions
  #5
sharath
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Hello, I want to know how I can incorporate transient boundary condition in Fluent.I have time dependant inlet velocity. Consider this as urgent. Thanks in advance. sharath.
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Old   September 13, 2004, 11:34
Default Re: Transient Boundary Conditions
  #6
Robin
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Try the Fluent forum.
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