2D turbulence closures for the barotropic jet instability simulation

In the present work the possibility of turbulence closure applying to improve barotropic jet instability simulation at coarse grid resolutions is considered. This problem is analogous to situations occurring in eddy-permitting ocean models when Rossby radius of deformation is partly resolved on a computational grid. We show that the instability is slowed down at coarse resolutions. As follows from the spectral analysis of linearized equations, the slowdown is caused by the small-scale normal modes damping arising due to numerical approximation errors and nonzero eddy viscosity. In order to accelerate instability growth, stochastic and deterministic kinetic energy backscatter (KEBs) parameterizations and scale-similarity model were applied. Their utilization led to increase of the growth rates of normal modes and thus improve characteristic time and spatial structure of the instability.

Study on Automobile Interior Noise Characteristic

This paper researched on four different types cars, analyzing interior noise at the same speed under different points, the same point different speeds and the same car different speed different points, it is concluded that family car interior noise distribution law; Through analysis noise spectrum curve which can get the main frequency band, that may provide theoretical basis for automotive noise reduction. In addition, this paper gets that medium low-frequency noise(0-2Brk) are the biggest to composition car’s characteristics loudness from research on characteristic loudness curve, and with speed continuously improve characteristic loudness growth is very significant.

Dynamical Simulation of Magnetorheological Fluid Characteristics

The aim of this research is to improve characteristic of magnetorheological fluid, and to supply theoretic basis for preparing MRF and applying MRF. By molecular dynamical simulation in MATLAB, microstructure of MRF, mechanism of MRF, and factors of affecting MRF characteristic were investigated. Based on theory of magnetic dipoles and microstructure characteristic of MRF, various factors affecting magnetic chain structure were considered, microcosmic model of MRF was established, factors affecting velocity of MRF forming chains were analyzed.