Search results for "Molecular chaos"
showing 3 items of 3 documents
Transport coefficients of self-propelled particles: Reverse perturbations and transverse current correlations
2019
The reverse perturbation method [Phys. Rev. E 59, 4894 (1999)] for shearing simple liquids and measuring their viscosity is extended to the Vicsek model (VM) of active particles [Phys. Rev. Lett. 75, 1226 (1995)] and its metric-free version. The sheared systems exhibit a phenomenon that is similar to the skin effect of an alternating electric current: Momentum that is fed into the boundaries of a layer decays mostly exponentially toward the center of the layer. It is shown how two transport coefficients, i.e., the shear viscosity $\ensuremath{\nu}$ and the momentum amplification coefficient $\ensuremath{\lambda}$, can be obtained by fitting this decay with an analytical solution of the hydr…
Modelling of Boltzmann transport equation for freeze-out
2005
The freeze-out (FO) in high-energy heavy-ion collisions is assumed to be continuous across finite layer in space–time. Particles leaving local thermal equilibrium start to freeze out gradually till they leave the layer, where all the particles are frozen out. To describe such a kinetic process we start from Boltzmann transport equation (BTE). However, we will show that the basic assumptions of BTE, such as molecular chaos or spatial homogeneity do not hold for the above-mentioned FO process. The aim of the presented work is to analyse the situation, discuss the modification of BTE and point out the physical causes, which yield to these modifications of BTE for describing FO.
Exact results for the homogeneous cooling state of an inelastic hard-sphere gas
1998
The infinite set of moments of the two-particle distribution function is found exactly for the uniform cooling state of a hard-sphere gas with inelastic collisions. Their form shows that velocity correlations cannot be neglected, and consequently the 'molecular chaos' hypothesis leading to the inelastic Boltzmann and Enskog kinetic equations must be questioned. © 1998 Cambridge University Press.