[praveensrikanth91]

I am in the process of adding phase change capabilities to the chtMultiRegionFoam solver for computing phase change at a liquid-vapor interface. However at this interface I would like to have a viscous coupling between the two phases as the vapor flow over the liquid would cause the liquid to have some internal flow. To do this I was planning to do something similar to the slip BC with zeroGradient for the tangential velocity across the interface and a fixedValue for the normal velocity (based on the phase change).

I worked it out for just the normal velocity but I am unable to figure out how to calculate the tangential velocity at the boundary. The boundary is not always aligned with the coordinate axes. Has anyone done this or have any experience with this?

I would imagine it would be beneficial to also equate the tangential stress components on both the domains for coupling.

Any help would be much appreciated

Thanks,
Praveen