how to get the unit volScalar, surfaceScalar and volVector
 

Hello every one,
I need to make a "unit phi" to get the div(phi,U)/mag(phi).
but in this case, the 1/mag(phi) may lead to a core dumped (floating point exception) error.

in fact, i try to make a surfaceScalar/volScalar/volVector such that:
-------------------------------------------------------

if ( mag(surfaceScalar) == 0 )
surfaceScalar = 0;
else
surfaceScalar/mag(surfaceScalar);
-------------------------------------------------------



can anyone help me?

I'm not sure what you want to achieve with "unit phi".

But to avoid FPE you can just simply add the machine epsilon in the denominator. Something like where VSMALL is float having magnitude 1.93e-34

in fact i am looking for a property on the cell face using *upwind* schemes, but without the phi magnitude.

for example .(mdot U) without the mdot magnitude.

by adding an small values, again, there is a possibility that the values ​​will be zero. because there are negative and positive values ​​of it.

stabilise() ? Eg, x / stabilise(y, SMALL)