you are not going to be able to mesh in hexa the solid that is a block. hexahedron (i,j,k) requires that a valid quad mesh (“i.e. there should be eight nodes shared by three quadrangles and the rest nodes should be shared by four quadrangles” from SMESH/share/doc/salome/gui/SMESH/basic_meshing_algos.html) which is not your case.
when you will divide correctly the geometry, (dividing the hexagonal block into 9 different blocks) you will not be able to run correctly the viscous layer addition. this happends as you have a 3 block, one edge situation, as i commented in this post Bug SMESH hexahedron + layer generation issue with internal faces of blocks so at least with this kind of blocking you will not be able to add a BL to it.