Flow characteristics are presented of simulation results of plane impinging jets at high nozzle-plate distances, with two k-ω based hybrid RANS/LES (Reynolds Averaged Navier–Stokes/Large–Eddy Simulation) models and a k-ω RANS model. The first hybrid RANS/LES model is obtained by substitution of the turbulent length scale by the local grid size in the destruction term of the turbulent kinetic en...

The eddy viscosity is the tensor in the equation that governs the transport of the large-scale (modulational) perturbations of small-scale stationary flows. As an approximation to eddy viscosity the effective tensor, that arises in the limit as the ratio between the scales ε → 0, can be considered. We are interested here in the accuracy of this approximation. We present results of computational...

In this paper we study existence and uniqueness of weak solutions for some non-linear weighted Stokes problems using convex analysis. The characterization of these considered equations is that the viscosity depends on the strain rate of the velocity field with a weight being a positive power of the distance to the boundary of the domain. These non-linear relations can be seen as a first approac...

where 2S is the viscosity computed by the Smagorinsky formulation (Smagorinsky, 1963), α is a constant in the range 0.01-0.5 and A denotes the area of the current element. A value of α = 0.1 was used keeping in mind the fine resolution of the mesh. Similar to the eddy viscosity, turbulent diffusion in the transport equations (equation 4 in the paper) represents all those processes that can not ...

Aims. We provide a consistent theory of the tachocline confinement (or anisotropic momentum transport) within an hydrodynamical turbulence model. The goal is to explain helioseismological data, which show that the solar tachocline thickness is at most 5% of the solar radius, despite the fact that, due to radiative spreading, this transition layer should have thickened to a much more significant...

Large-eddy simulation (LES) has become a widely-used method for computation of field-scale environmental flows; however, challenges remain in determining the optimal turbulence closure method. Recently, the concept of explicit filtering and reconstruction has become recognized as a means to obtain more accurate simulation results (Carati et al. 2001, Winckelmans et al. 2001, Stolz et al. 2001, ...

This article presents a new turbulence closure based on the k-ω SST model for predicting turbulent flows of Herschel–Bulkley fluids, including Bingham and power-law fluids. The has been calibrated with direct numerical simulations (DNS) data fully-developed pipe flow shear-thinning viscoplastic shows good agreement in mean velocity, average viscosity, shear stress budget friction factor. latter...

Large Eddy Simulation (LES) has become an increasingly attractive option for turbulence modeling due to the rise in computing power and the improvement in sub-grid scale (SGS) parameterizations. This study tests the improvements in simulations of wall-bounded flows over heterogeneous surfaces attained by the implementation of three improvements in the eddy-viscosity SGS closure: the dynamic mod...