Effect Of Horizontal Flow On The Flow Characteristics Of The Flow Layer Heated Form The Bottom

The "heat island" effect in the urban, Ocean circulation in the ocean and Environmental pollution caused by industrial sewage in the industry, they all come down to convective motion.According to the different mechanism of production, convective motion can be divided into natural convection and forced convection, the natural convection is caused by the change of density which came into being by concentration difference or temperature difference; However forced convection is driven by external force. This paper is mainly to study the thermal convection, thermal convection is a kind of convection among natural convection, which is also a way of heat transfer. Thermal convection is a process which the hot and cold parts of the liquid or the gas through the circulation flow to made the temperature tends to be uniform.Rayleigh-Benard convection model can be commendably used to study the thermal convection,domestic, foreign experts and scholars widely use the Rayleigh-Benard convection model . The model is simple and easy to control, convenient to carry out theoretical analysis. Through the research of scientific workers, the research results of Rayleigh-Benard convection are obtained,these research results can not only reveal the convection phenomenon well, which can also enrich the research of basic disciplines such as physics, classical mechanics and fluid mechanics.According to the fluid of Prandtl number at Pr = 6.99,0.72,0.0272 , numerical simulation of 2-D equations of hydrodynamics is used in this paper; The effects of the height of the cavity,the horizontal flow and the periodic heating on the spatiotemporal structure, the convection pattern and the convection characteristics of Rayleigh-Benard convection are studied. The results are as follows:(1) In the aspect of the cavity height: When cavity height is selected atd = 1d0,1.4d0,1.8d0,2d0,3d0 , the dynamic characteristics of convective motion are studied. It is found that the number of convective cell number decreases with the increase of the cavity height d, and the convective wave number k is kept constant. After convective reached stable,the relationship between the convection amplitude , the Nusselt number and the cavity heightd is studied.(2) In the aspect of the horizontal flow: Under the effect of horizontal flow, the following conclusions can be obtained from the research of the convection: 1. The process of the convective growth can be divided into three stages, namely, convective development,convective exponential growth and periodic variation; In the exponential growth phase, the linear growth rate increases with the increase of the reduced Rayleigh number; The dependence of the traveling wave period on the horizontal flow Reynolds number. 2. The localized traveling wave has the horizontal flow upper and lower critical Reynolds number, and the horizontal flow upper and lower critical Reynolds number increases with the reduced Rayleigh number increasing. 3. The convection pattern is divided into the traveling wave region, the local traveling wave region, the horizontal flow region; the convective pattern exist two perturbation growth models in the three region. 4. the horizontal flow width of the localized traveling wave vary with the horizontal flow Reynolds number and the reduced Rayleigh number.(3) In the aspect of the periodic heating: The bottom of the chamber is periodically heated, the variation of the fluid motion with horizontal flow is studied, the steady period of the localized traveling wave motion vary with the horizontal flow Reynolds number, the local traveling wave motion interval depend on the horizontal flow Reynolds number.