Experimental investigation of Reynolds stress complex eddy viscosity model for coherent structure dynamics

Spectral and hyper eddy viscosity in high-Reynolds-number turbulence

For the purpose of studying the spectral properties of energy transfer between large and small scales in high-Reynolds-number turbulence, we measure the longitudinal subgrid-scale (SGS) dissipation spectrum, defined as the co-spectrum of the SGS stress and filtered strain-rate tensors. An array of four closely spaced X-wire probes enables us to approximate a two-dimensional box filter by averag...

A dynamic global-coefficient subgrid-scale eddy-viscosity model for large-eddy simulation in complex geometries

Experimental Investigation on the Viscosity of Nanofluids

In this study, the effect off adding SiO2 nanoparticles on the viscosity of base fluid is investigated experimentally. Base fluids are chosen among common heat transfer fluids such as ethylene glycol, transformer oil and water. In addition different volume percentages of ethylene glycol in water are used as ethylene glycol-water solution. In every base fluid different volume fractions of SiO2 n...

A Coherent vorticity preserving eddy-viscosity correction for Large-Eddy Simulation

This paper introduces a new approach to Large-Eddy Simulation (LES) where subgrid-scale (SGS) dissipation is applied proportionally to the degree of local spectral broadening, hence mitigated or deactivated in regions dominated by large-scale and/or laminar vortical motion. The proposed coherentvorticity preserving (CvP) LES methodology is based on the evaluation of the ratio of the test-filter...

Reynolds Stress and Eddy Diffusivity of b-Plane Shear Flows

The Reynolds stress induced by anisotropically forcing an unbounded Couette flow, with uniform shear g, on a b plane, is calculated in conjunction with the eddy diffusivity of a coevolving passive tracer. The flow is damped by linear drag on a time scale m. The stochastic forcing is white noise in time and its spatial anisotropy is controlled by a parameter a that characterizes whether eddies a...