the estimation of velocity distribution plays a major role in the hydrodynamics of vegetated streams or rivers of extensive natural floodplains. the velocity profile in vegetated channels can be divided into three zones: uniform zone which is close to bed with uniform velocity distribution, logarithmic zone which involves the main channel with no vegetive cover and the transition zone that is a...

Turbulent Prandtl number distributions are measured in a laboratory boundary layer flow with bed roughness, active blowing and sucking, and scalar injection near the bed. The distributions are significantly larger than unity, even at large distances from the wall, in apparent conflict with the Reynolds analogy. An analytical model is developed for the turbulent Prandtl number, formulated as the...

We use DNS to study the effect of Prandtl number on mixing in weakly density stratified Kelvin-Helmholtz (KH) billows at low to moderate Reynolds numbers. The time evolution of the density field of the flow and the mixing are significantly influenced by the Prandtl number. By increasing the Prandtl number, the final amount of mixing increases for Reynolds that are too low to sustain three-dimen...

The growth of secondary vortices on the braids separating Kelvin–Helmholtz billows is investigated via numerical simulations. The similarity theory of Corcos & Sherman (1976) is extended to include mixing processes with Prandtl number greater than unity, and is shown to provide a useful description of the physics of the braid regions just prior to the onset of secondary instability. The numeric...

A model for the kinematic eddy viscosity has been developed which accounts for the turbulence produced as a result of jet interactions between adjacent streams as well as the turbulence initially present in the streams. In order to describe the turbulence contribution from jet interaction, the eddy viscosity suggested by Prandtl has been adopted, and a modification has been introduced to accoun...

Rayleigh-Taylor mixing is a classical hydrodynamic instability that occurs when a light fluid pushes against a heavy fluid. The two main sources of nonideal behavior in Rayleigh-Taylor (RT) mixing are regularizations (physical and numerical), which produce deviations from a pure Euler equation, scale invariant formulation, and nonideal (i.e., experimental) initial conditions. The Kolmogorov the...

In this paper, we use Prandtl mixing-length theory and semiempirical to extend the classical problem of wind in steady atmospheric Ekman layer with constant eddy viscosity. New generalized equations are established qualitative properties corresponding ODEs studied. Spatial wave solutions results for nonlinear implicit different nonlinearities presented.