Fix/make versioncheck compatible with CMake 3.1

Closes #669

See merge request !1517

[fix][cmake][handbook] Replace VERSION_GREATER_EQUAL by NOT .. VERSION_LESS to be backward-compatible

Dennis Gläser authored 6 years ago and Timo Koch committed 6 years ago

This flux variables cache precomputes the shape values at the tpfa
flux support point necessary on interior boundary scvfs with Neumann
BCs specified on them.

Dennis Gläser authored 6 years ago and Timo Koch committed 6 years ago

This way we can formulate the flux dependent on both the matrix as
well as the facet permeability. This significantly reduces the condition
number of the resulting matrix and thus improves newton convergence.

Feature/facetcoupling with mpfa

See merge request !1431

Dennis Gläser authored 6 years ago and Timo Koch committed 6 years ago

On 3d grids, the maximum value of 8-bit integer types can easily be
surpassed for the local indices within interaction volumes. We use the
larger local index type now. This way we should always be on the safe
side.