ISSN Online: 2377-424X
International Heat Transfer Conference 12
Recent advances in numerical simulation of 3D unsteady convection controlled by buoyancy and rotation
Résumé
Various approaches to generate 3D unsteady numerical solutions for non-isothermal turbulent flows under action of buoyancy and/or rotation are discussed. Well-known techniques are Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES). With reference to applications of the LES technique in problems of engineering interest, a special attention is paid to near-wall-layer models dealing with coarse or moderate grids. A recently developed technique based on a hybridisation of Reynolds-Averaged Navier-Stokes models with LES (RANS/LES) is described. Results of examination of LES and RANS/LES capabilities as compared with known high-accuracy DNS data for turbulent Rayleigh-Benard convection in a rotating horizontal layer are discussed. A promising experience of application of RANS/LES technique to strongly turbulent thermal convection of mercury in a cylindrical cell is presented. Recent achievements in LES and RANS/LES of molten silicon turbulent convection in real-geometry rotating crucibles of Czochralski (CZ) systems for single-crystal growth are reviewed. Attention is paid to capabilities of these numerical techniques to predict baroclinic instabilities at the melt periphery and high-intensity fluctuations in the under-crystal region, playing a primary role in formation of macroscopic inhomogeneities of the growing crystal. Results of DNS studies of 3D unsteady mixed convection developing in a rapidly rotating annular cavity are described in comparison with known experimental data for a simplified model of configurations typical for axial compressors of high-temperature gas turbines.