任意物質の坮縮性熱対流が計算できる数値解法

摘要

これまでの数値流体力学（CFD）研究では，主に空rn気を対象とした圧縮性流れ，もしくは水を対象にしたrn非圧縮性流れが解析できるそれぞれの数値解法が数多rnく提案されてきた．前者は理想気体を仮定し，後者はrn密度変化なしと仮定される．これらの仮定に基づいたrn汎用のCFDソフトウエアも国内外でいくつか市販さrnれている．%A numerical method for simulating compressible thermal convections of arbitrary substance is presented. The numerical method is based on the preconditioning method proposed by the authors. This method is coupled with a database of thermochemical properties, PROPATH, developed by Kyushu University. Since PROPATH has accurate thermochemical models for 48 substances, the present method can calculate flows of such substances accurately. Also PROPATH can be used for not only substances in a gas state but also those in liquid and supercritical states. In this paper as numerical examples, natural convections in a square cavity for several substances, such as carbon-dioxide, water, nitrogen, methane and helium are calculated assuming gas and liquid conditions and the calculated results are compared with the existing numerical results and with each other. Especially, the natural convection of water liquid near 4℃ is calculated and the anomalous convection is captured and the results are compared with the existing numerical and experimental results.