Kinetic Model for Sheared Granular Flows in the High Knudsen Number Limit

Kinetic model for sheared granular flows in the high Knudsen number limit.

The sheared granular flow of rough inelastic granular disks is analyzed in the high Knudsen number limit, where the frequency of particle-wall collisions is large compared with particle-particle collisions, using a kinetic theory approach. An asymptotic expansion is used in the small parameter epsilon =(nsigmaL), which is the ratio of the frequencies of particle-particle and particle-wall colli...

Discrete unified gas kinetic scheme for all Knudsen number flows: low-speed isothermal case.

Based on the Boltzmann-BGK (Bhatnagar-Gross-Krook) equation, in this paper a discrete unified gas kinetic scheme (DUGKS) is developed for low-speed isothermal flows. The DUGKS is a finite-volume scheme with the discretization of particle velocity space. After the introduction of two auxiliary distribution functions with the inclusion of collision effect, the DUGKS becomes a fully explicit schem...

A diffusive information preservation method for small Knudsen number flows

Keywords: DSMC IP Molecular diffusion Time step Cell size a b s t r a c t The direct simulation Monte Carlo (DSMC) method is a powerful particle-based method for modeling gas flows. It works well for relatively large Knudsen (Kn) numbers, typically larger than 0.01, but quickly becomes computationally intensive as Kn decreases due to its time step and cell size limitations. An alternative appro...

Velocity autocorrelations and viscosity renormalization in sheared granular flows.

The decay of the velocity autocorrelation function in a sheared granular flow is analyzed in the limit where the wavelength of fluctuations is larger than the "conduction length," so that energy is a nonconserved variable. The decay of the velocity autocorrelation function is much faster than that in a fluid at equilibrium for which energy is a conserved variable. Specifically, the autocorrelat...

A slip model for rarefied gas flows at arbitrary Knudsen number