Topic
Velocity gradient
About: Velocity gradient is a research topic. Over the lifetime, 3013 publications have been published within this topic receiving 77120 citations.
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TL;DR: In this paper, the Boussinesq approximation has been used to model buoyancy effects on momentum transfer in a cubical cavity heated from below by means of the three-dimensional computation of the time dependent Navier-Stokes and energy transport equations in the range of Rayleigh numbers 3500 ⌽Ra ⩽ 10 000.
63 citations
TL;DR: The second-order invariant modeling technique for turbulent flows as developed by Donaldson is applied to the atmospheric surface layer as mentioned in this paper, where the steady, high-Reynolds number equations reduce to a universal set when the variables are scaled by the shear stress and vertical heat flux as suggested by Monin and Obukhov.
Abstract: The second-order, invariant modeling technique for turbulent flows as developed by Donaldson is applied to the atmospheric surface layer. The steady, high-Reynolds number equations reduce to a universal set when the variables are scaled by the shear stress and vertical heat flux as suggested by Monin and Obukhov. Numerical integration of these equations yields results for the mean velocity gradient, mean temperature gradient, Richardson number, rms vertical velocity and temperature fluctuations, and horizontal heat flux which agree favorably with experimental observations over the complete range of stability conditions.
63 citations
Metz1
TL;DR: In this paper, the evolution of texture in Equal Channel Angular Extrusion (ECAE) is discussed in detail, and a more precise flow field which uses an analytical flow function is proposed.
Abstract: The majority of the techniques of severe plastic deformation calls for simple shear deformation mode. This is why a special interest is given in this paper to textures that develop in simple shear. The evolution of texture in Equal Channel Angular Extrusion (ECAE) is also discussed in detail. The classical “simple shear model” of ECAE is examined as well as a new, more precise flow field which uses an analytical flow function. The proposed function is inspired from finite element calculations. The velocity gradient that follows from the analysis is incorporated into the self consistent viscoplastic polycrystal code. The evolution of deformation texture is predicted up to two passes in the A-route ECAE deformation of copper polycrystal when the extrusion angle is 90°.
63 citations
TL;DR: In this article, the SST k-ω turbulence scheme with turbulence damping at the interface gives better predictions than the standard K-e and RNG k-e models for the case under consideration.
63 citations
TL;DR: In this article, the authors derived explicit analytic formulas for the linear growth rate and the frequency in the combination of Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) instabilities in fluids with continuous density and velocity profiles.
Abstract: We have derived explicit analytic formulas for the linear growth rate and the frequency in the combination of Kelvin–Helmholtz (KH) and Rayleigh–Taylor (RT) instabilities in fluids with continuous density and velocity profiles. It is found that the density gradient effect (i.e., the density transition layer) decreases the linear growth rate in the RT instability (RTI), especially for the short perturbation wavelength. The linear growth rate for the KH instability (KHI) is increased by the density gradient effect but decreased by the velocity gradient effect (i.e., the velocity transition layer). The frequency in the KHI is reduced by both the density gradient effect and the velocity gradient effect. In most cases, both the linear growth rate and the frequency are decreased by the combination of density and velocity transition layers, i.e., the combined effect of density and velocity gradients stabilizes the KHI. The density gradient effect has an opposite influence on the linear growth rates of the RTI an...
63 citations