A numerical study of laterally strained wall-bounded turbulence

Abstract

Direct numerical simulation (DNS) is used to study the effects of mean lateral divergence and convergence on wall-bounded turbulence, by applying uniform irrotational temporal deformations to a plane-channel domain. This extends a series of studies of similar deformations. Fast and slow straining fields are considered, leading to a matrix of four cases, all corresponding to zero-pressure-gradient (ZPG) flows along the centreplane in ducts with constant rectangular cross-sectional area but varying aspect ratio. The results are used to address basic physical and modelling questions, and create a database that allows detailed yet straightforward testing of turbulence models. Initial tests of three representative one-point models reveal meaningful differences. The extra-strain effects introduced by the matrix of fast and slow divergence and convergence are documented, separating the direct effects of the strain from the indirect ones that alter the shear rate and change the distance from the wall. Some findings are predictable, and none contradict experimental findings. Others require more thought, notably an asymmetry between the effect of convergence and divergence on the peak turbulence kinetic energy.

Turbulence structural measurements using a comprehensive laser–Doppler velocimeter in two- and three-dimensional turbulent boundary layers

“…As noted by many previous authors, there is a reduction in the near-wall TKE and Reynolds shear stress for a wide array of 3D TBLs and correspondingly in the TKE and shear stress production, the present flow included (Simpson, 2005;Coleman et al, 2000;Moin et al, 1990;Ölc ßmen and Simpson, 1996;Eaton, 1995). In the present data, reduction of the near-wall TKE and Reynolds shear stress production (not plotted) is accompanied by reduced values of P ii compared with the 2DFPTBL (Fig.…”

“…The importance of the velocity-pressure gradient term in wall-bounded threedimensional (3D) flows has been shown for low Reynolds numbers by the DNS of Coleman et al (2000). In the strained channel flow DNS, those authors discovered that P ij is of primary importance to the evolution of the Reynolds stresses.…”

Non-equilibrium three-dimensional boundary layers at moderate Reynolds numbers

“…Despite equilibrium 3DTBL, such as the Ekman layer, are of paramount importance (see e.g. Spalart (1989); Coleman et al (1990); Littell & Eaton (1994); Wu & Squires (1997); Coleman et al (2000)), the subject of the present work is the non-equilibrium response of 3DTBL, which is one of the most challenging cases for the current turbulence theories. In addition to their equilibrium state (or lack thereof), 3DTBL are also classified according to the mechanisms by which the three-dimensionality is incorporated into the flow.…”

Effects of distributed pressure gradients on the pressure–strain correlations in a supersonic nozzle and diffuser

“…The turbulence production is separated into production by mean shear and applied strain, showing that the net increase in TKE in the outer layer can be traced back to the production by extra strain. Recently, Coleman et al (2009) have used DNS to study the pure effects of mean lateral divergence and convergence on wall-bounded turbulence, by applying the strained channel strategy (see Coleman et al 2003). Irrotational strain (∂W/∂z = −∂V/∂y) deforms the constant-area duct (including the walls) and the in-plane wall motion emulates the zero-pressure-gradient (ZPG) condition in streamwise direction.…”