SYMMETRY GROUPS OF BOUNDARY-LAYER EQUATIONS OF A CLASS OF NON-NEWTONIAN FLUIDS

A non-Newtonian fluid model in which the stress is an arbitrary functi on of the symmetric part of the velocity gradient is considered. Symme try groups of the two-dimensional boundary layer equations of the mode l are found by using exterior calculus. The complete isovector field c orresponding to some cases, such as arbitrary shear function, Newtonia n fluids, and power-law fluids, are found. Similarly, solutions for so me special transformations are presented. Results obtained in a previo us paper [M. Pakdemirli, Int. J. Non-Linear Mech. 29, 187 (1994)] usin g special groups of transformations (scaling, spiral) are verified in this study using a general approach. (C) 1996 Elsevier Science Ltd.