LAMINARIZATION OF TURBULENT GAS-FLOW INSIDE A STRONGLY HEATED TUBE

A numerical study is performed to investigate thermal transport phenom ena of the laminarizing flow in a strongly heated circular tube. A k-e psilon turbulence model is employed to determine the turbulent viscosi ty and the turbulent kinetic energy. The turbulent heat flux is expres sed by Boussinesq approximation in which the eddy diffusivity for heat is determined by a t(2)-epsilon(t) heat-transfer model. Both models a re slightly modified to improve the accuracy in the turbulent-to-lamin ar transition region. The governing boundary-layer equations are discr etized by means of a control volume finite-difference technique and nu merically solved using a marching procedure. Results are obtained for Stanton number, turbulent kinetic energy, temperature variance and vel ocity and temperature dissipation time scales in laminarizing flow. (C ) 1997 Elsevier Science Ltd.