2009 年 75 巻 749 号 p. 1-10
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.