Natural convection in an annulus between coaxial horizontal cylinders with internal heat generation

Natural convection of gas (Pr = 0.7) between two horizontal coaxial cylinders with uniform internal heat generation is numerically investigated. Such a problem plays an important role in the analysis of lasers in which a similar circuit of a heat-conducting path is used. It has been found that the behavior of the system critically depends on three parameters including the inverse relative gap width σ(=diameter of the inner cylinder/gap width), the Rayleigh number Ra and the modified Rayleigh number RaT which describes heat generation. In the case RaT = 0 our results coincide with the known ones. It has been established that in such a system there exist two types of fluid flow for low Rayleigh numbers with different vortex structure. Optimization of the corresponding coaxial laser system has been analyzed.