# Q)How do I calculate the gross flow across a plane?A)Sometimes it is useful to know the flow across a plane in one direction only instead of the net flow.For example it may be useful to know how much total flow is coming in across an opening.In CFX-Post create an expression for the velocity normal to a face, e.g:LIBRARY: CEL: EXPRESSIONS: VelFaceExp=max(u*nx+ v*ny+w*nz, 0.0 [m/s]) END ENDENDwhere (nx,ny,nz) are the x,y,z components of the unit normal vector, that is normal to the required face.The max function ensures that only flows in the direction of the normal give a positive result.Then create a scalar variable using this expression:USER SCALAR VARIABLE:VelFace Boundary Values = Conservative Calculate Global Range = Off Expression = VelFaceExp Recipe = Expression Variable to Copy = PressureENDThe gross flow across a plane is then given by the area integral of the variable over the required locator.This works for bondaries and CFX-Post locators, e.g:flow = areaInt(VelFace)@openingflow = areaInt(VelFace)@Plane 1

 Q)How do I calculate the gross flow across a plane?A)Sometimes it is useful to know the flow across a plane in one direction only instead of the net flow.For example it may be useful to know how much total flow is coming in across an opening.In CFX-Post create an expression for the velocity normal to a face, e.g:LIBRARY: CEL: EXPRESSIONS: VelFaceExp=max(u*nx+ v*ny+w*nz, 0.0 [m/s]) END ENDENDwhere (nx,ny,nz) are the x,y,z components of the unit normal vector, that is normal to the required face.The max function ensures that only flows in the direction of the normal give a positive result.Then create a scalar variable using this expression:USER SCALAR VARIABLE:VelFace Boundary Values = Conservative Calculate Global Range = Off Expression = VelFaceExp Recipe = Expression Variable to Copy = PressureENDThe gross flow across a plane is then given by the area integral of the variable over the required locator.This works for bondaries and CFX-Post locators, e.g:flow = areaInt(VelFace)@openingflow = areaInt(VelFace)@Plane 1