关键词: time-dependent rotating flow, non-Newtonian fluid, Oldroyd fluid B, computational symbolic manipulation, computational analytical approach

Abstract: A combination of the computational symbolic calculation, mathematical approach and physico-mechanical model leads to a computational intellectual analytical approach developed by the author. There is a principal difference between the computer proof and the computer derivation completed by the computer,also difference between the numerical and symbolic calculations. In this investigation the computational analytical approach is extended,and an unsteady flow of non-Newtonian fluid in the gap between two rotating coaxial cylinders is studied. The Oldroyd fluid B model is used by which the Weissenberg effects are explained in a good comparison with the experiments. The governing equations are reduced to a partial differential equation of 3rd order for the dimensionless velocity. Using the computer software Macsyma and an improved variational approach the problem with the initial and boundary conditions is then reduced to a problem of an ordinary differential equation for different approximations. The analytical solutions are given for the 1st, 2nd and 3rd approximations. The present investigation shows the ability of the computational symbolic manipulation in solving the problems of non-Newtonian fluid flows. There is a possibility of that to solve the problems in mathematics and mechanics. An important conclusion can be drawn from the results that the transition from a steady state to another steady state is non-unique.

Key words: time-dependent rotating flow, non-Newtonian fluid, Oldroyd fluid B, computational symbolic manipulation, computational analytical approach