Merge branch '71-wrong-automatic-definition-of-the-laplacian-coefficient-2' into 'branch_4.2'

Resolve "Wrong automatic definition of the laplacian coefficient"

Closes #71 (closed)

See merge request !298 (merged)

(cherry picked from commit 3d32aa16)

5f746cf4 Change Reynolds nb from 1/12 to 1/2 (Laplacian)