How to prescribe a hyperbolic tangent profile into a transition interface of a field
 

Hello Everyone,

I've added a scalar transport equation into icoFoam for a concentration field (denoted as C). So generally the varying distribution of the field C is governed by the added transport equation. See the attached image, the pure red region where C=+1 represents one phase and the pure blue where C=-1 means the other. But for transition layer where the concentration changes from -1 to +1 , I want to prescribe a hyperbolic tangent profile C = tanh(x/a) where x indicates the local coordinate normal to the transition layer/interface, a is a parameter.

So could anyone give me some suggestions or hints on how to prescribe the profile for the transition layer? Thank you very much in advance.

Regards,
Xuan

How you introduced Hyperbolic tangent stretching in blockMesh? I want to do this as well.