(cherry picked from commit b613999c)

(cherry picked from commit b3cf5c2eb5dad849b6c8d71552ca995fbe7a487e)

(cherry picked from commit 07a4f9636751c016f7e73ff58b988da59f735921)

(cherry picked from commit eb6aadaaa24eff6acdd8563f1b5fef1b3ed21e2a)

cherry-pick 56b49f3

(cherry picked from commit 1c1c12968df801d995d39e0aaa4d2950eee7a73a)

(cherry picked from commit 4d49e04593989485e1c3710fe497fb45ae41d588)

(cherry picked from commit 77aca325)

before only one channel side could have a velocity boundary condition (bc). When setting a bc at a second side, the first bc was overwritten.
Velocity bcs were fied in the previous commit (bda2c544271657adfabb63e9ae974e77692566a6). This commit fixes the boundaryQs for velocity.

(cherry picked from commit 811e344b)

before only one channel side could have a velocity boundary condition (bc). When setting a bc at a second side, the first bc was overwritten.

(cherry picked from commit daa787a3)