Comparison of calculated and experimental heat transfer coefficients at the surface of circular cylinders placed in a turbulent cross-flow of air

Heat transfer coefficients have been calculated using computational fluid dynamics (C.F.D.) at the surface of an infinite circular cylinder (d = 0.1 m) subjected to a turbulent cross-flow of air whose velocity and turbulence intensities ranged from 0.5 to 5.0 m.s(-1) and from 1.5 to 40%, respectively. The turbulence was accounted for by a k-epsilon model completed by near-wall treatment based either on a wall function or on Wolfshtein's low-Reynolds number model. Results confirm that the wall function approach leads to great differences between calculated and experimental mean transfer coefficients. However; mean transfer coefficients are described efficiently by Wolfshtein's model providing that the variation of the damping of turbulent viscosity with the boundary sublayer thickness is considered Finally this payer :shows that the prediction of surface coefficients by C.FD. calculations alone has to he taken with caution. (C) 1998 Elsevier Science Limited. All rights reserved.