[ndtrong]

Hi everyone,


I have a question about interface curvature as below:
Following definition of interface curvature, is defined as:

in which is normal vector of interface that is defined based on volume fraction in each cell as:

So:
is volVectorField and then is volScalarField, is that correct?

However, in interFoam solver, is defined on cell face () as:

where is defined by interpolation computation as:

then, face unit interface normal flux is defined as:


with is the normal vector of cell face (Note that then is a surfaceScalarField).

Then, interface curvature is defined as:


My question is:
- why do we need to interpolate the to cell face.
- when we mention about normal vector of interface (interface normal vector) which one is correct defined at cell's center or defined at cell's face?