Help: diffusive flux BC at wall

Quarkz

hi,

i've written a non-staggered FVM NS solver based on fractional step in cartesian grid. i've used the BC based on peric's book which states that du/dx & dv/dy =0 at the wall, hence diffusive flux at wall=0. my diffusive flux are also handled implicitly

now i'm modifying to structured grids. there's no transformation involved and i'm evaluating the fluxes in the physical face. hence, i'm still using u & v in x,y components

Now along the wall boundary, du(n)/dn=0 as before. however, my cell centered vel are still in x,y components. how do i make use of du(n)/dn=0 or do i just neglect this condition?

Thanks alot!