How to get normal vector to the face?
 

In the framework of my project I want to do the separation of zones by specific criteria. This results in generation of new interfaces (face zones).

The question is: is there a Schema-function or UDF-function using which I could determine whether the normal vector to the given face zone or face is directed inwards or outwards of the given adjacent cell zone?

The sign of such a normal vector affects the surface flux reporting and gives positive or negative signs, depending on the direction of the normal vector. However, I want to report all incoming fluxes as positive and all outcoming fluxes as negative. This is only possible if I know the direction of the normal vector.

I can see the 'averaged normal' in the properties of the interface of 'fan' type, but it is not reported by any function. I can also compute 'X Surface Area' and 'Y Surface Area' which can be also positive or negative, but they only make sense for rectangular zones and provide no useful information for curved interfaces.

So I need the function to get either coordinates of normal vector for each individual face (then I can determine threads and zones, and define the direction) or the direction of normal to the interface in respect to the adjacent zone.

Does anybody know how to do this in Schema or in the UDF?

hi Viatcheslav, Though it's a long time but I'm faceing the same problem.Have you figured it out?