Two and Three Dimensional Numerical Simulations of Accretion Discs in a   Close Binary System
  We perform 2D and 3D numerical simulations of an accretion disc in a close binary system using the Simplified Flux vector Splitting (SFS) finite volume method. In our calculations, gas is assumed to be the ideal one, and we calculate the cases with gamma=1.01, 1.05, 1.1 and 1.2. The mass ratio of the mass-losing star to the mass-accreting star is one. Our results show that spiral shocks are formed on the accretion disc in all cases. In 2D calculations we find that the smaller gamma is, the more tightly the spiral winds. We observe this trend in 3D calculations as well in somewhat weaker sense.   Recently, Steeghs, Harlaftis & Horne (1997) found the first convincing evidence for spiral structure in the accretion disc of the eclipsing dwarf nova binary IP Pegasi using the technique known as Doppler tomography. We may claim that spiral structure which we have discovered in numerical simulations before are now found observationally. 
Makoto Makita, Kenji Miyawaki, Takuya Matsuda (Kobe University)