SESSION 7
MIXED AND FREE CONVECTION
NUMERICAL STUDY OF MIXED CONVECTION IN VERTICAL PIPE FLOWS WITH INLET FLOW RATE STEP. APPLICATIONS TO WATER RADIATORS
T.H. MAI, N. ELWAKIL, J. PADET(*)
(*) Laboratoire de Thermomécanique, UTAP
Faculté des Sciences, BP 1039, 51687 Reims (France)
In this paper we study a transient mixed convection problem. We consider a water flow in a vertical tube, submitted to a flow rate step. The characteristics of the transient velocity and temperature fields have been investigated numerically by a finite-difference procedure. The simulations have been performed with positive or negative steps. It is shown a dissymetry in the response of the system which can be characterized by two parameters: time lag and time constant. A strong difference in the temporal distributions of velocity and temperature profiles between these two cases, is also observed.
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