Modeling of Unsteady Turbulent Flow in a Buried Co-Axial Exchanger—The Use of Green's Functions Theory

Abstract

This work presents an analytical and numerical investigation of the heat transfer problem of turbulent flow under forced convection in a buried co-axial exchanger. A hybrid model consisting of a finite element method at the boundary (BEM) for the heat transfer problem on the boundary, and a finite volume method (FVM) to solve the turbulent flow inside solves this complicated problem. The development of the BEM method is based on Green's functions theory. The mathematical model employed makes a scientific contribution to a similar practical situation. The results can be of great interest for industrial processes requiring the estimation of the heating time necessary to obtain steady states. Essentially, the axial evolution of the heat transfer coefficient versus Reynolds number and transfer duration is treated here. The temperature field and the heat flux density at the wall are also investigated.

The authors thank R. Schiestel of Institut de Recherche sur les Phénomènes Hors Equilibre (I.R.P.H.E), UMR 6594 CNRS, Marseille, France for his generous help. The authors also wish to thank Mr. J. Y. Desmons of Laboratoire de Mécanique et Energétique (L.M.E) de l'Université de Valenciennes, France.