Pressure as the variable in Expression in CFX-Pre

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 February 16, 2005, 14:42 Pressure as the variable in Expression in CFX-Pre #1 Atit Koonsrisuk Guest   Posts: n/a Please someone suggest me how to use 'Pressure' and 'area' at a certain face inside the domain as the variable in 'Expressions' of CFX-Pre. I would like to define one variable in 'Expressions' of CFX-Pre as the function of the pressure at one certain face of my domain. I found the name of face is F5.B1.P3 and the formula is the pressure at that face times face area. However I do not know how to define that pressure. I already tried: Pressure@F5.B1.P3 and Pressure()@F5.B1.P3 and Pressure("F5.B1.P3") and massFlowAve(Pressure)@F5.B1.P3 but none of them is acceptable. Do anyone know how to define the pressure at certain face in 'Expressions' In addition, Function Calculator in CFX-Post can compute 'area' at any face, so there must be 'area' as the parameter in CFX, isn't it? However I have no idea how to get 'area' to use in CFX-Pre. I have tried: area@F5.B1.P3 and area()@F5.B1.P3 they all doesn't work. In my domain, there are some 2D regions that I specify the boundary conditions. For example, I have 'in' as the 2D region for 'Inlet' boundary condition. I have tried area@in CFX accept this definition, but the preprocessor does not support its evaluation in CFX-Pre. Do I have to define F5.B1.P3 as the 2D region? I think that we define 2D region for specifying boundary conditions, while this face is the face on fluid subdomain for energy source, which need not any boundary condition. So I think specify it as 2D region is not right, isn't it? Thank you very much for your kind consideration. Atit

 February 16, 2005, 14:55 Re: Pressure as the variable in Expression in CFX- #2 Juan Carlos Guest   Posts: n/a Hi, The callback functions within CFX-Pre and the CFX-Solver only support the use of regions that are defined as : domain, sub-domain, boundary, domain interfaces, point sources or monitor points. There is no mechanism for accessing a face that is not a boundary or a domain interface. Can you make that region a domain interface? and treat the subdomain as a domain? For further information, you can look at the CEL Variables, Functions and Constants section of the CFX-5.7/5.7.1 documentation. Regards, Juan Carlos

 February 16, 2005, 15:09 Re: Pressure as the variable in Expression in CFX- #3 Atit Koonsrisuk Guest   Posts: n/a Dear Carlos, Thank you very much for your kind answer. I follow your suggestion by defining that face as the domain interface named 'ADin'. As I stated earlier that area@in do work, but area@ADin doesn't work. Why? In addition, do you have idea how to use pressure, because even Pressure@in doesn't work Thank you very much. Atit

 February 16, 2005, 16:18 Re: Pressure as the variable in Expression in CFX- #4 Juan Carlos Guest   Posts: n/a Hi, When you refer to the domain interface, you should refer to a side of it. Then, you really refer to the boundary on the side you are interest in. I think that will solve the area@ADin problem.. Second, callbacks are single value functions.. You cannot access the Pressure array on a boundary via a callback yet.. You can average, min, max the array but not access the array itself.. You may be confused with the syntax, for example area is a function not a variable with syntax area@location. Other example is areaAve(variable, like Pressure)@location. For example, to obtain the area integral of Pressure over a surface, you do : areaInt(Pressure)@location Regards, Juan Carlos

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