ANALYSIS OF THE HEAT TRANSFER BY LAMINAR FLOW IN THERMAL ENTRANCE REGION OF A CONDUIT WITH WAVY SURFACE SUBJECTED TO A UNIFORM WALL HEAT FLUX

Abstract

Thermal developing laminar Poiseuille flow via a conduit with wavy surface is studied taking plane and cylindrical geometries as a case in point. A transformation procedure from the original system with wavy walls heated by a type of heat change to the one of straight walls subjected to periodic heat flux of the same period is proposed. Then, by the functional analysis method the solution in thermal entry area is obtained with regard to uniform inlet temperature and neglecting both viscous dissipation and the axial conduction. Mean and local Nusselt numbers from Nusselt as well as temperature in the entrance region are obtained for a conduit with small amplitude of the wavy walls. The principal results presented show that the solution regarding the two geometries has the same form and describe completely the original problem, and the optimization of the system for walls with low amplitude corresponds to large dimensionless pulsation for great values of Péclet number.