corrected the visc bcs
Merge branch 'fluidity-core/MultiFluids_Dev' of github.com:FluidityProject/fluidity into fluidity-core/MultiFluids_Dev
Merge branch 'fluidity-core/MultiFluids_Dev' of github.com:FluidityProject/fluidity into fluidity-core/MultiFluids_Dev
corrected the visc bcs