CFD Online Discussion Forums

CFD Online Discussion Forums (
-   Siemens (
-   -   mass flow in a specified surface (

lenson January 26, 2005 04:54

mass flow in a specified surface
Recently My teacher asked me to get a mass flow rate at a specified surface. how can I do ? because the inner built button does not exist such function for directly usage. can anyone help me using codes to caculate the mass flow rate in a specified surface ?

Mir January 26, 2005 10:48

Re: mass flow in a specified surface
You can specify the section plane and then use the INTEGRATE command. You should define a macro or panel to do easily this calculation.

lenson January 27, 2005 04:26

Re: mass flow in a specified surface
after using the command "integrate" I find there are five values computeted. there are NO.CELL TOT A TOT A*VN TOT A*S TOT A*VN*S But I don`t know the terminology "TOT A"ĦB" TOT A*VN" "TOT A*S" "TOT A*VN*S"

Volker January 27, 2005 08:19

Re: mass flow in a specified surface
TOT = Total A = Area VN = Vector Normal S = Scalar

Brian January 27, 2005 10:45

Re: mass flow in a specified surface
Like Volker said... :)

Also keep in mind the following:

INTEGRATE, RANGE: Integrates the currently selected (cell) post data items on the plane defined by the SPOINT and SNORMAL commands and prints the results to the screen. Cell data are treated as constant within the volume of each cell. Therefore, the integration simply sums the cell value times the area of the slice through each cell. Vector components (fluid velocities) are first resolved into a system that is normal and parallel to the given plane. Then the normal component only is used. This method is not exact and will provide only a rough estimate of the integrated values.

Obviously, finer meshes will yield more accurate values than coarser meshes located in the same geometry. To use this command, make sure that all three cell velocity components are loaded in the global Cartesian system and the appropriate scalar (or user item created via the OPERATE command) is loaded into register 4.

Note: The areas are all multiplied by the scale factor used last to write out geometry file.

All times are GMT -4. The time now is 17:57.