A convective model for a laminar unsteady ducted flow

The main lines of a numerical model especially built to analyze the dynamic and thermal developments for laminar pulsed ducted flows are presented. The energy and Navier-Stokes equations are treated by a finite-difference method using asymptotic developments for the different dynamic and thermal functions. An annular effect in temperature is presented and the evolution of its damping along the axis. Its relation to the unsteady temperature gradient at the wall and to the correlated heat transfer behavior is shown. The importance of the unsteady velocity and temperature amplitudes in the first development steps have been pointed out. These amplitude effects could be at the origin of an added steady flux and, too, of dynamic and thermal stresses at the wall of the entry zone.