Two-dimensional hydrodynamical simulations were made to calibrate the mixing length parameter for modeling red giant's convective envelope. As was briefly reported in Asida & Tuchman 1997, a comparison of simulations starting with models integrated with different values of the mixing length parameter, has been made. In this paper more results are presented, including tests of the spatial resolu...

Two-dimensional hydrodynamical simulations were made to calibrate the mixing length parameter for modeling red giant’s convective envelope. As was briefly reported in Asida & Tuchman 1997, a comparison of simulations starting with models integrated with different values of the mixing length parameter, has been made. In this paper more results are presented, including tests of the spatial resolu...

Some basic aspects of dynamics and transport in polar regions within one or two scale heights of the summer mesopause are examined, and the implications for local one-dimensional photochemical modeling of those regions discussed. Included is a simple thought experiment on gravity wave breaking that throws further light on the so-called "turbulent Prandtl number" question, and related questions....

We demonstrate a reduction in the measured inner wall shear stress in moderately turbulent Taylor-Couette flows by depositing sprayable superhydrophobic microstructures on the inner rotor surface. The magnitude of reduction becomes progressively larger as the Reynolds number increases up to a value of 22% at Re=8.0×10(4). We show that the mean skin friction coefficient C(f) in the presence of t...

We propose a semi-discrete in time semi-implicit numerical scheme for the infinite Prandtl model for convection. Besides the usual finite time convergence, this scheme enjoys the additional highly desirable feature that the stationary statistical properties of the scheme converge to those of the infinite Prandtl number model at vanishing time step. One of the key characteristics of the scheme i...

An empirical correlation for predicting the heat transfer coefficient for a cylinder under free convection, inclined at any arbitrary angle with the horizontal has been developed in terms of Nusselt number, Prandtl number and Grashof number. Available experimental data was used to determine the parameters for the proposed correlation. The proposed correlation predicts the available data well wi...

Direct numerical simulation of a fully developed turbulent channel flow with passive scalar transport has been carried out at four Reynolds numbers, 180, 395, 640 and 1020, based on the friction velocity and the channel half width. The molecular Prandtl numbers are 0.025 and 0.71 where the working fluids are assumed to be mercury and air, respectively. It is shown that for both Prandtl numbers,...

Amplification of magnetic field due to kinematic turbulent dynamo action is studied in the regime of small magnetic Prandtl numbers. Such a regime is relevant for planets and stars interiors, as well as for liquid-metal laboratory experiments. A comprehensive analysis based on the Kazantsev-Kraichnan model is reported, which establishes the dynamo threshold and the dynamo growth rates for varyi...

Abstract A gas-cooled nuclear reactor combined with a Brayton cycle shows promise as technology for high-power space power systems. Generally, helium–xenon gas mixture molecular weight of 14.5–40.0 g/mol is adopted the working fluid to reduce mass and volume turbomachinery. The Prandtl number mixtures this recommended mixing ratio may be low 0.2. As convective heat transfer closely related numb...