HEAT-TRANSFER IN TRANSIENT AND UNSTEADY FLOWS PAST A HEATED CIRCULAR-CYLINDER IN THE RANGE 1 LESS-THAN-OR-EQUAL-TO R LESS-THAN-OR-EQUAL-TO 40

The response of a heated circular cylinder to impulsive and sinusoidal variations in the velocity of flow past it has been simulated by numerical integration of the governing equations. The fluid has been treated as viscous and incompressible and as having constant properties. The range of Reynolds number investigated was 1 ≪ R ≪ 40. Since vortex shedding normally does not occur in this range, the flows were treated as symmetrical. The thermal and flow transients are presented for the following cases.: (i)impulsive starts from rest to final steady state Reynolds numbers 1, 5, 10, 26·67; (ii)impulsive increases in velocities of 50% magnitude from steady state Reynolds numbers 1, 10 and 26·67; (iii)sinusoidal variation in velocity with amplitude of 10% impressed on a mean flow at Reynolds number 10. Results are also given for the thermal transients associated with instantaneous changes in cylinder temperature at Reynolds numbers 1, 5 and 40. The results obtained for transient and steady state flow parameters are in agreement with those obtained numerically and experimentally by other workers and the results for steady state heat flux from the cylinder are in agreement with experimental values. The new results obtained for heat transfer in unsteady flows provides information which is relevant to the operation of hot-wire anemometers. © 1979, Cambridge University Press