Laminar transport phenomena in constricted parallel ducts

Abstract

A finite-difference numerical method is developed to solve heat and momentum transfer problems in viscous, incompressible, laminar flow through parallel ducts with abrupt contraction and enlargement. Consideration is given to two limiting thermal conditions: constant wall temperature and constant wall heat flux. Theoritical results are obtained for the loss coefficients due to abrupt contraction and expansion, heat transfer performance and combined hydrodynamic and thermal entrance length. The effects of the flow-area variation, thermal boundary conditions, and Reynolds and Prandtl number on the contraction and expansion coefficients, entrance length, and local and average Nusselt number are determined. The present numerical scheme is capable of producing results for the complex channel flows up to the transition Reynolds number. It is disclosed that the flow constrictions cause a substantial enhancement in heat transfer.