题目:Heat Transport in Turbulent Thermal Convection 主讲:Professor Quan Zhou (Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University) 时间:9月11日(星期四)15:00 地点:力学一楼239
内容简介: Thermal convection is an efficient means to carry heat flux across space by a moving fluid, and it is ubiquitous in nature. A classical model system to study such phenomenon is Rayleigh-Bénard convection (RBC), i.e. the motion of a fluid layer that is heated from below and cooled from above. Due to the buoyancy instability the fluid moves and carries a heat flux upwards, which is typically many times of that by thermal diffusion. An important question to ask is how much heat flux moves through the RBC cell given an enclosed fluid and an imposed temperature difference across the cell. This heat flux is usually characterized by a non-dimensional parameter, defined as the Nusselt number Nu, which depends largely on the control parameters of the system, such as the Rayleigh number Ra, the Prandtl number Pr, and the aspect ratio of the convection cell. In this talk, I will introduce our recent works on heat transfer problems, i.e. the dependence of Nu on (Ra, Pr, ). Especially, I will report an experimental and numerical study that reveals a novel mechanism that leads to dramatically enhanced heat transport, i.e. when partition walls are inserted into a convection cell with thin gaps left open between the partition walls and the cooling/heating plates, it is found that the convective flow becomes much more coherent and self- organized, leading to a dramatically enhanced heat transport of up to 2.3 times that without any partitions. We expect that this surprising discovery might bring profound changes in many industrial applications where thermal flux through a fluid is involved.