SIMILARITY ANALYSIS OF BOUNDARY-LAYER EQUATIONS OF A CLASS OF NON-NEWTONIAN FLUIDS

A similarity analysis of three-dimensional boundary layer equations of a class of non-Newtonian fluids in which the stress is an arbitrary f unction of rates of strain is made. It is shown that under scaling tra nsformation, for an arbitrary stress function, only 90-degrees of wedg e flow leads to similarity solutions, whereas for a specific more rest ricted form, similarity solutions exist for arbitrary wedge angles. In the case of spiral group transformation, no similarity solutions exis t if we force the stress function to remain arbitrary after the transf ormation, whereas for a specific more restricted form, similarity solu tions exist for arbitrary wedge angles. For both transformations, simi larity equations for power-law and Newtonian fluids are presented as s pecial cases of the analysis. Finally the conditions for invariance an d the form of the stress function for a two-dimensional case are also presented.