M. Skote et al., Direct numerical simulation of self-similar turbulent boundary layers in adverse pressure gradients, FLOW TURB C, 60(1), 1998, pp. 47-85
Direct numerical simulations of the Navier-Stokes equations have been carri
ed out with the objective of studying turbulent boundary layers in adverse
pressure gradients. The boundary layer flows concerned are of the equilibri
um type which makes the analysis simpler and the results can be compared wi
th earlier experiments and simulations. This type of turbulent boundary lay
ers also permits an analysis of the equation of motion to predict separatio
n. The linear analysis based on the assumption of asymptotically high Reyno
lds number gives results that are not applicable to finite Reynolds number
flows. A different non-linear approach is presented to obtain a useful rela
tion between the freestream variation and other mean flow parameters. Compa
rison of turbulent statistics from the zero pressure gradient case and two
adverse pressure gradient cases shows the development of an outer peak in t
he turbulent energy in agreement with experiment. The turbulent flows have
also been investigated using a differential Reynolds stress model. Profiles
for velocity and turbulence quantities obtained from the direct numerical
simulations were used as initial data. The initial transients in the model
predictions vanished rapidly. The model predictions are compared with the d
irect simulations and low Reynolds number effects are investigated.