Hi,

I've run a simulation of two rooms separated by a thin surface with a hole in between the two. This is part of a larger solution domain. I want to measure the mass flow from room 1 in to room 2, so I have created a user surface from a points file to cover the hole between the two spaces. On the Tools tab in Post, I have calculated the mass flow, which for some cases is positive and for some, it is negative. I know the sign convention is based on positive if the direction of flow is in the direction of the surface normal, but how do I find out which way is the surface normal?

Thanks in advance,

Nicki

Create a vector using the variable Normal on the surface.

Fab. Thanks very much.