CONVENTIONAL AND MULTIPLE DECK BOUNDARY-LAYER APPROACH TO 2ND AND 3RDGRADE FLUIDS

A general analysis of boundary layers of second and third grade fluids are made in which the conventional as well as the multiple deck struc tures are investigated. It is shown that for second grade fluids only conventional two deck structure exists and a multiple deck boundary la yer is impossible. For the third grade fluids, three conventional boun dary layers are formulated. In the first one, we retain all the terms whereas in the second one the viscous, and in the third one, second gr ade terms come out to be negligible compared to other terms. A similar ity solution is presented for the third case. Under some restricted co nditions, it is shown that quadruple decks exist for the third grade f luids. For the lower deck equations to be matched with the middle deck equations, a decaying solution should exist, and this further require s that 2alpha1 + alpha2 = 0 where alpha1 and alpha2 are the material m oduli for third grade fluids.