ISSN Online: 2377-424X
ISBN Print: 0-89116-299-2
International Heat Transfer Conference 7
MODELING ASSUMPTIONS FOR TURBULENT HEAT TRANSFER
要約
In order to improve existing modeling
assumptions for the turbulent heat transfer we
start with the transport equation for the Reynolds
heat flux. We neglect the convective and diffusive
terms. This is approximately valid for boundary
layer type flow not too far from equilibrium. In
connection with Prandtl's well known k-model, our
modeling assumptions lead to a simple algebraic
formula Prt = K1 + K2/(Pr Rem) for the turbulent
Prandtl number which agrees very well with known
experiments. Based on this expression, the Reynolds
heat flux, the thermal diffusivity, and the
temperature profiles are determined for a fully
developed turbulent tube flow with constant heat
transfer rate. Finally, the Nusselt number is
calculated and compared with empirical relationships
as well as measurements. Our numerical results
for the Nusselt number are approximated by
a simple formula Nu = A + B (Pr Re)n.