Reynolds stress budgets for both Couette and boundary layer flows are evaluated and presented. Data are taken from direct numerical simulations of rotating and non-rotating plane turbulent Couette flow and turbulent boundary layer with and without adverse pressure gradient. Comparison of the total shear stress for the two flows suggests that the Couette case may be regarded as the high Reynolds...

Recently found unstable time-periodic solutions to the incompressible Navier-Stokes equation are reviewed to discuss their relevance to plane Couette turbulence and isotropic turbulence. It is shown that the periodic motion embedded in the Couette turbulence exhibits a regeneration cycle of near-wall coherent structures, which consists of formation and breakdown of streamwise vortices and low-v...

The stability of compressible plane Couette flow, which is a simple case of hypersonic wall-bounded shear flows, is not well understood even though incompressible Couette flow has been studied extensively by linear stability analysis and shown to be stable to linear disturbances. As a first step in studying the stability of three-dimensional hypersonic boundary layers, this paper studies the te...

We have conducted a numerical studv of spherical Couette Vlow -the flow between differentiallv rotatin~ concentric spheres. When the qa D ratio o{(R2-RI)/RI (where R 1 and R 2 are the radii of the inner and outer spheres) is small, the flow near the e~uator resembles that between cylinders, the classic Tavlor-Couette ~roblem. As in Tavlor-Couette flow, when the angular momentum gradient, measur...

We show that turbulent "spirals" and "spots" observed in Taylor-Couette and plane Couette flow correspond to a turbulence-intensity modulated finite-wavelength pattern which in every respect fits the phenomenology of coupled noisy Ginzburg-Landau (amplitude) equations with noise. This suggests the existence of a long-wavelength instability of the homogeneous turbulence regime.

We study a large-scale instability in a sheared nonhelical turbulence that causes generation of large-scale vorticity. Three types of the background large-scale flows are considered, i.e., the Couette and Poiseuille flows in a small-scale homogeneous turbulence, and the "log-linear" velocity shear in an inhomogeneous turbulence. It is known that laminar plane Couette flow and antisymmetric mode...

A mesoscale kinetic-type approach is proposed to solve shear driven micro flows of binary gas mixtures in MEMS. The coupled linear integro-differential equations, which formally describe the flow, are solved using the discrete velocity method. The complicated collision integral term is approximated by the McCormack model. The proposed approach is applied in one and two dimensions, solving the C...

The threshold amplitude for subcritical transition in Poiseuille and Couette ows is investigated. For Poiseuille ow we present examples where the threshold scales like R ?7=4 for 1500 R 5000, where R is the Reynolds number. For Couette ow we present an example where the threshold scales like R ?5=4 for 500 R 2000.

This study focuses on the dynamics of the Taylor-Couette Vortex Flow (TVF) in a photo-bioreactor in which CO2 is changed to O2 with high efficiency by the photosynthesis ability of micro algae. Stirring by means of a screw propeller is generally used for a simple agitation. However, the problem is that there exists a very high shearing flow region just near the propeller, which causes the destr...