Equation Icon  l d-vli = λDlvli +-δi,0S--(vr0 − vl0), i = 0,− 1,− 2,..., (10.38 ) dt Δxl σl00 d r r r δi,0Sr l r --vi = λD vi + ---r-r-(v0 − v0), i = 0,1,2,.... (10.39 ) dt Δx σ00