[luckyluke]

Requested reference cell 0 is on a constraint boundary, selecting reference cell 1?

[henry]

The reference cell location and value are used for the solution of the pressure equation when zeroGradient BCs are applied on all boundaries. However, the current implementation of matrix manipulation to apply this constraint does not handle the coefficients on constraint boundaries and hence cannot be applied to cells that lie on constraint boundaries. We will rewrite matrix constraints to handle and solve this and other problems with the current implementation when we get time but until then I added a search procedure to find a cell not on a constraint boundary.