Laminar and Turbulent Natural Convection in Cavities: Numerical Modeling and Experimental Validation

摘要

In the study the authors consider natural convection determined flows in large enclosed spaces. Some examples of spaces where natural convection is extremely important or even dominant are: heated rooms, large factory halls, greenhouses, cooled food storage containers, clean rooms, underground coal gasification cavities, flat plate solar collectors, nuclear reactor vessels or waste containers, densely packed dissipating microelectronics, cavity-walls and double-glazing of windows. The most important dimensionless group in natural convection is the Rayleigh number. The number is a measure of the ratio of buoyant forces to viscous forces. Depending on the value of the Raleigh number, but also on other parameters, the flow in the enclosure can be laminar, turbulent or both flow regimes can be present in different parts of the enclosure. The Rayleigh number generally is high in large enclosures most often leading to turbulent flow.