抄録
It was shown in [J. Phys. Soc. Jpn. 52 (1983) 3382] that there are two theoretically sound simulation methods for solving the Boltzmann equation; one is Nanbu’s method and the other is Belotserkovskiy and Yanitskiy’s method. The only defect of these methods is in that the computation time is proportional to the square of the number of simulated molecules. Here is proposed an approximation the use of which makes the computation time directly proportional to the number of molecules. The essence of the approximation lies in using the collision probability in Nanbu’s method or the collision rate in Belotserkovskiy and Yanitskiy’s method averaged over local equilibrium distribution function. The error of the approximation is small over a wide range of the degree of nonequilibrium.
