Large eddy simulation of a developing turbulent boundary layer at a low Reynolds number

Abstract

SUMMARYA spectral code has been used to simulate a developing turbulent boundary layer at low Reynolds number Re, (based on free stream velocity and momentum thickness) between 353 and 576. The starting field was generated by allowing a step change of temperature to diffuse outwards from one wall in a fully developed channel flow. The thermal boundary layer so created was conditionally sampled to convert it into a momentum boundary layer with an irrotational free stream region, a process which is justified by appeal to experiments. This initial field was allowed to develop until the momentum bsundary layer thickness a, , ,had grown to about 1.5 times its Original thickness. The results of the simulation have been compared with a wide range of experimental data. The outcome of this comparison is generally very satisfactory; the main trends of the experiments are well reproduced and our simulation supplements and extends the existing sets of experimental data. The simulation also gives pressure statistics which cannot be obtained experimentally. In particular, it gives the contribution of pressure diffusion to the balance equations for the Reynolds stress and indicates the error produced by omitting this term.

Turbulent Two-Dimensional Shear Flows

“…For a flat plate, ßU; = 2.8, but this value (strongly dependent on constants used in the log law) tends to decrease when Ra < 6000 (Coles, 1962) and falls to zero at Ra '" 465. Murlis et Al., 1982, Tsai & Leslie, 1990). Murlis et Al., 1982, Tsai & Leslie, 1990).…”