新衝突法を適用した超音速不足膨張噴流の三次元dsmc解析（平行噴流の相互干渉と矩形孔からの自由噴流）

摘要

直接シミュレーションモンテカルロ法（DSMC法）（1）rnは希薄気体流の解析法として開発されたが，計算機技rn術の発展に伴って，その適用範囲は，連続流状態までrn広がる傾向にある．DSMC法は，計算の発散とぃっrnた不安定要素がなく，また，境界条件も比較的与え易rnぃ．一方，DSMC法で最も問題となるのは，流れ場のrnセル分割を，平均自由行程と同程度の細かさで行う必rn要があるとぃう点である．%A supersonic free jet through a multi-aperture circular orifice that induces plume-plume interaction or through a rectangular orifice is investigated by the DSMC method with an improved new collision scheme. When the DSMC method is applied to a continuum or a near continuum fluid, the most serious problem is that it is necessary to divide the flow-field into a network of cells the dimension of which is smaller than the local mean free path. At the meeting of the RGD23 and RGD24, Usami et al. has proposed a new intermolecular collision scheme (U-system) in which velocity components of a molecule are modified according to positions of a collision pair and it enables a large cell dimension. The collision scheme (U-system 3) proposed in the present paper conserves the total energy of each collision pair precisely during an intermolecular collision and improves the stability of the scheme.