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Multiscale non-equilibrium physics at large variations of local Knudsennumber are encountered in applications of aerospace engineering andmicro-electro-mechanical systems, such as high-speed flying vehicles and lowpressure of the encapsulation. An accurate description of flow physics in allflow regimes within a single computation requires a genuinely multiscalemethod. The adaptive unified gas-kinetic scheme (AUGKS) is developed for suchmultiscale flow simulation. The AUGKS applies discretized velocity space toaccurately capture the non-equilibrium physics in the multiscale UGKS, andadaptively employs continuous distribution functions following Chapman-Enskogexpansion to efficiently recover near-equilibrium flow region in GKS. The UGKSand GKS are dynamically connected at the cell interface through the fluxes fromthe discretized and continuous gas distribution functions, which avoids anybuffer zone between them. In this study, the AUGKS method with rotation andvibration non-equilibrium is developed. The real gas effect in different flowregimes has been captured. To capture aerodynamic heating accurately, the heatflux modifications are also included. Unstructured discrete particle velocityspace is adopted to further improve the computational performance. Numericaltests, including Sod tube, normal shock structure, high-speed flow around thetwo-dimensional cylinder and three-dimensional sphere and space vehicles, andan unsteady nozzle plume flow from the continuum flow to the background vacuum,have been conducted to validate the current scheme. In comparison with theoriginal UGKS, the current scheme speeds up the computation, reduces the memoryrequirement, and maintains the equivalent accuracy for multiscale flowsimulation, which provides an effective tool for non-equilibrium flowsimulations, especially for the flows at low and medium speed.

Adaptive unified gas-kinetic scheme for diatomic gases with rotational and vibrational nonequilibrium