Subscriber I'm sorry I wasn't clearer earlier. Please refer to the picture in my original post above. I'm adding a source term to model the surface tension which is exactly the same as the CSF model by Brackbill et al. already implemented in Fluent, but there is one small change which is indicated in bold at the bottom of the image (I want to smoothen the interface by changing the definition of the cell phase fraction, and area-averaging it).

@DrAmine, @Rob, Could you please guide on how to calculate the laplacian of a scalar? The scalar in this case is stored in UDS0 right now. I know that I can get the first derivative of that using UDSI_G for that UDS0. I can get the unit vector by dividing the gradient by its magnitude. But for getting the divergence of the unit vector, I'll have to get the derivative of that and sum the x and y components right? How do I go about doing that?n