tallred11
posted this
29 January 2019

- Last edited 29 January 2019
So, are you saying this approach won't give an accurate angle?

It seems a bit odd to me to look at the VOF gradient in a *cell* and dot it with the *face* area normal. What face would you use? Also, it seems we would need an additional step to get to an angle.

Currently, I find the cell with a VOF value closest to 0.5 that is in the row of cells closest to the wall. Then, I look at the volume fraction gradient in this cell and obtain the radial component of the gradient (in an axisymmetric simulation).

The manual states that for wall adhesion (which I'm not using but the same concepts should apply), the equation for the contact angle is n = n_w*cos(theta)+t_w*sin(theta), where n is the unit vector of the gradient of the volume fraction. Thus, the radial component of the gradient, divided by the magnitude of the gradient, should equal the t_w*sin(theta) term. So I take the arcsin of that value.

But I'm not very satisfied with the results. They seem to vary strangely and I'm not confident in the accuracy of the angle based on this gradient in a single cell. But, it seems that the approach you provided would be more or less the same unless I'm not understanding it properly.