  In 2010, the unified gas kinetic scheme (UGKS) was proposed by Xu et al . (A
unified gas-kinetic scheme for continuum and rarefied flows, Journal of
Computational Physics, 2010). In the past decade, many numerical techniques
have been developed to improve the capability of the UGKS in the aspects of
efficiency increment, memory reduction, and physical modeling. The methodology
of the direct modeling of the UGKS on discretization scale provides a general
framework for construction of multiscale method for multiscale transport
processes. This paper reviews the development and extension of the UGKS in its
first decade.
