In turbomachinery flows, the boundary-layer can remain laminar up to 70% of the chord length, due to a relatively low local Reynolds number on the blade. The high free-stream turbulence intensity penetrates into the laminar boundary-layer by the combined action of turbulence diffusion and pressure fluctuations, and triggers the transition process to a turbulent state. This transition process is...

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...

A new Boussinesq-type model describing periodic wave propagation over a constant depth has been developed for the cases where the effects of a turbulent boundary layer are significant. In this paper, the eddy viscosity model is employed in the turbulent boundary layer and is further approximated as a linear function of the distance measured from the seafloor. The boundary-layer velocities are c...

Toroidal magnetic fields subject to the Tayler instability can transport angular momentum. We show that the Maxwell and Reynolds stress of the nonaxisymmetric field pattern depend linearly on the shear in the cylindrical gap geometry. Resulting angular momentum transport also scales linear with shear. It is directed outwards for astrophysical relevant flows and directed inwards for superrotatin...

Simulations of stochastically forced shear-flow turbulence in a shearing-periodic domain are used to study the spontaneous generation of large-scale flow patterns in the direction perpendicular to the plane of the shear. Based on an analysis of the resulting large-scale velocity correlations it is argued that the mechanism behind this phenomenon could be the mean-vorticity dynamo effect pioneer...

The " local-equilibrium " hypothesis that assumes a local balance between the viscous dissipation and the subgrid-scale dissipation at the same physical location in turbulent flow has been commonly used for turbulence modeling. For example, based on the local equilibrium hypothesis, Germano et al. (1991) and Moin et al. (1991) developed dynamic procedures for determining the model coefficients ...

Aims. To understand the fundamental physical processes important for the evolution of solar rotation and distribution of chemical species, we provide theoretical predictions for particle mixing and momentum transport in the stably stratified tachocline. Methods. By envisioning that turbulence is driven in the tachocline, we compute the amplitude of turbulent flow, turbulent particle diffusiviti...

The flow and turbulence in an IC engine cylinder were studied using the SSG variant of the Reynolds stress turbulence closure model. In-cylinder turbulence is characterized by strong turbulence anisotropy and flow rotation, which aid in air-fuel mixing. It is argued that solving the differential transport equations for each turbulent stress tensor component, as implied by second-moment closures...

An eddy-viscosity based, subgrid-scale model for Large Eddy Simulations is derived from the analysis of the singular values of the resolved velocity gradient tensor. It is shown that the proposed σ-model has the property to automatically vanish as soon as the resolved field is two-dimensional, including the pure shear and solid rotation cases. In addition, the model generates no subgrid-scale v...

A general solution for the eddy viscosity within the surface layer is presented on the basis of rst order closure. Eddy viscosity for stable or unstable stratiication is calculated for given friction velocity, buoyancy ux and length scale. The turbulent length scale is obtained from comparison with several empirical prooles of the diabatic wind proole. Zusammenfassung Eine allgemeine LL osung d...