  When the molecules of a gaseous system are far apart, say in microscale gas
flows where the surface to volume ratio is high and hence the surface forces
dominant, the molecule-surface interactions lead to the formation of a local
thermodynamically non-equilibrium region extending few mean free paths from the
surface. The dynamics of such systems is accurately described by Boltzmann
equation. However, the multi-dimensional nature of Boltzmann equation presents
a huge computational challenge. With the recent mathematical developments and
the advent of petascale, the dynamics of full Boltzmann equation is now
tractable. We present an implementation of the recently introduced
multi-species discontinuous Galerkin fast spectral (DGFS) method for solving
full Boltzmann on streaming multi-processors. The present implementation solves
the inhomogeneous Boltzmann equation in span of few minutes, making it at least
two order-of-magnitude faster than the present state-of-art stochastic
method---direct simulation Monte Carlo---widely used for solving Boltzmann
equation. Various performance metrics, such as weak/strong scaling have been
presented. A parallel efficiency of 0.96--0.99 is demonstrated on 36 Nvidia
Tesla-P100 GPUs.
