高温加熱鉛直平板周りに発達する自然対流境界層の乱流遷移過程の時空間構造

抄録

We performed a large-eddy simulation for a natural convection boundary layer along a vertical plate heated at high temperature, which gave the turbulence transition with the significant non-Boussinesq effects. An open source CFD code, Fire FOAM, was used to consider the density fluctuation effects directly and the one-equation model was applied to estimate SGS components. The spatial distributions of statistics with Reynolds decomposition clearly showed the transition at Grz ≅ 10⁹; this critical Gr number agreed with that in the boundary layer without non-Boussinesq effects. The non-Boussinesq effects were definitive in the amplification process of fluctuations, i.e., the density fluctuations primarily generated the velocity fluctuations with reduction in correlation with temperature fluctuations.