A computational study of laminar flow and heat transfer to highly viscous pseudoplastic fluids in vertical pipes under constant heat flux is presented. Experimental local heat transfer coefficients are compared with the predictions by computer simulation based on the equations of continuity

momentum and energy. The numerical predictions fit the experimental data excellently. The results show that the difference in radial temperature is very large in heat transfer to highly viscous fluids. It is demonstrated that in order to minimize the difference in radial temperature and wall temperature it is necessary to use a smaller pipe diameter

which is an effective measure to solve the problem.