Direct numerical simulations of turbulence resulting from Kelvin–Helmholtz instability in stably stratified shear flow are used to study sources of anisotropy in various spectral ranges. The set of simulations includes various values of the initial Richardson and Reynolds numbers, as well as Prandtl numbers ranging from 1 to 7. We demonstrate that small-scale anisotropy is determined almost ent...

Reynolds' paper sought to explain the change in character of flow through a pipe from laminar to turbulent that his earlier experiments had shown to occur when the dimensionless group that today bears his name exceeded approximately 2000. This he did by decomposing the velocity into mean and fluctuating components and noting how the average kinetic energy generation and dissipation rates change...

The high-order statistics of fluctuations in velocity gradients in the crossover range from the inertial to the Kolmogorov and sub-Kolmogorov scales are studied by direct numerical simulations (DNS) of homogeneous isotropic turbulence with vastly improved resolution. The derivative moments for orders 0 ≤ n ≤ 8 are represented well as powers of the Reynolds number, Re, in the range 380 ≤ Re ≤ 22...

We use silicon strip detectors (originally developed for the CLEO III high energy particle physics experiment) to measure fluid particle trajectories in turbulence with temporal resolution of up to 70,000 frames per second. This high frame rate allows the Kolmogorov time scale of a turbulent water flow to be fully resolved for 140 ≥ Rλ ≥ 970. Particle trajectories exhibiting accelerations up to...

At present, the radius of wind turbine rotors ranges from several meters to one hundred meters, or even more, which extends Reynolds number of the airfoil profile from the order of 105 to 107. Taking the blade for 3MW wind turbines as an example, the influence of Reynolds number on the aerodynamic design of a wind turbine blade is studied. To make the study more general, two kinds of multi-obje...

The entropy generation analysis of fully turbulent convective heat transfer to nanofluids in a circular tube is investigated numerically using the Reynolds Averaged Navier–Stokes (RANS) model. The nanofluids with particle concentration of 0%, 1%, 2%, 4% and 6% are treated as single phases of effective properties. The uniform heat flux is enforced at the tube wall. To confirm the validity of the...

the paper numerically presents laminar forced convection of a nanofluid flowing in a duct at microscale. results were compared with both analytical and experimental data and observed good concordance with previous studies available in the literature. influences of brinkman and reynolds number on thermal and hydrodynamic indexes have been investigated. for a given nanofluid, no change in efficie...

A spatially confined stability analysis is reported for the cylinder wake at Reynolds numbers 190 and 260. The two three-dimensional instabilities at these Reynolds numbers are shown to be driven by the flow just behind the cylinder.

In this article, mixed convection heat transfer of alumina-water nanofluid in an inclined and baffled C-shape enclosure is studied. It is assumed that the flow is laminar and steady. There is no energy production, energy storage and viscous heat dissipation. Furthermore, the nanofluid is considered as a continuous, Newtonian and incompressible fluid. Governing equations are discretized by finit...

In this work, the stencil adaptive method is applied to investigate the effects of a magnetic field on mixed convection of Al2O3-water nanofluid in a square lid-driven cavity. The incompressible Navier-Stokes equations are solved by an adaptive mesh method which has superior numerical advantages compared to the traditional method on the uniform fine grid. The main objective of this study is to ...