# measure flow through a hole in cfd post

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 August 19, 2010, 09:10 measure flow through a hole in cfd post #1 New Member   name Join Date: Mar 2009 Posts: 9 Rep Power: 16 Hi, I have a problem in CFD post. Inside my fluid domain, I have a structure which has two holes for an opening. I want to compare the fluid flow of those two holes. I could use an expression to evaluate the mass flow. However I dont have a location (plane, etc.) for those two holes. Is it possible to select create a location for the hole? The geometry looks something like this: Code: ```--- ---- --- ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ --------------``` Thanks a lot!

 August 19, 2010, 18:26 #2 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,366 Rep Power: 139 Yes. It is a bit clunky but it can be done. You need to define a surface to integrate the flow over somehow - options include planes with limits, contour surfaces or I think you can import XYZ points as user surfaces. Then use the function calculator to get the flow rate (or whatever you want) across the surface.

 August 20, 2010, 05:19 #3 New Member   name Join Date: Mar 2009 Posts: 9 Rep Power: 16 thanks, that helped. now i can calculate the massflow with an expression, but how could i calculate the heat flow?

 August 22, 2010, 18:29 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,366 Rep Power: 139 use the function calculator to get the heat flux integrated over the surface.

 August 23, 2010, 03:20 #5 New Member   name Join Date: Mar 2009 Posts: 9 Rep Power: 16 but it says that the variable is not available on the plane. is it in general only available on boundaries and interfaces, as it says in the help or is there a chance to use it on planes?

 August 23, 2010, 07:36 #6 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,366 Rep Power: 139 Sorry, I meant general heat flux, not the variable heat flux which is only at the walls. Integrate the enthalpy.