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The purpose of this study is to investigate the natural convection in a Γ-shaped enclosure using hybrid thermal lattice Boltzmann method (HTLBM). The vertical walls are at cold temperature while the horizontal walls are adiabatic. In our mathematical formulation, a 2D Multiple Relaxation Time-Lattice Boltzmann Equation (MRT-LBE) D2Q9 and Finite Difference Method (FDM) are applied for fluid velocity and temperature respectively. Results are presented, for different step size and for Rayleigh number varying from 103 to 106, in form of isotherms, streamlines and Nusselt number. It is observed that the step height and the buoyancy force, induced by the temperature difference, significantly affect the velocity and temperature distributions and the rate of heat transfer from the heated wall.

A numerical investigation to simulate the fluid flow and heat transfer in a two-dimensional horizontal channel containing a multi heated physical rectangular bodies is conducted using hybrid thermal lattice Boltzmann method (HTLBM). A combination between the Multiple Relaxation Time-Lattice Boltzmann Equation (MRT-LBE) D2Q9 for fluid velocity and Finite Difference Method (FDM) for temperature is used. In the plane channel, the bodies are placed in a side-by-side arrangement and normal to the incoming flow. The air flow is assumed to be laminar and incompressible. Special attention is paid to investigate the effect of the Reynolds number on the fluid flow and the heat transfer, where the dimensions and the distance between the bodies are fixed.

In this paper, the power spectrum density theoretical model of an entirely random modulation signal function, that means random carrier with random pulse position technique, is established. The entirely random switching signal can spread electromagnetic energy concentrated in modulation carrier frequency and is more effective suppression conduction EMI than one simple variable random modulation technique formerly in power electronics. The spectral estimation method is consistent with the model calculation results. The effects of random range for two random variables are discussed.