Reyes Francisco Vega, Garzó Vicente, Khalil Nagi
Departamento de Física, Universidad de Extremadura, 06071 Badajoz, Spain.
Phys Rev E Stat Nonlin Soft Matter Phys. 2014 May;89(5):052206. doi: 10.1103/PhysRevE.89.052206. Epub 2014 May 13.
Segregation induced by a thermal gradient of an impurity in a driven low-density granular gas is studied. The system is enclosed between two parallel walls from which we input thermal energy to the gas. We study here steady states occurring when the inelastic cooling is exactly balanced by some external energy input (stochastic force or viscous heating), resulting in a uniform heat flux. A segregation criterion based on Navier-Stokes granular hydrodynamics is written in terms of the tracer diffusion transport coefficients, whose dependence on the parameters of the system (masses, sizes, and coefficients of restitution) is explicitly determined from a solution of the inelastic Boltzmann equation. The theoretical predictions are validated by means of Monte Carlo and molecular dynamics simulations, showing that Navier-Stokes hydrodynamics produces accurate segregation criteria even under strong shearing and/or inelasticity.
研究了在驱动的低密度颗粒气体中，由杂质的热梯度引起的分离现象。该系统被封闭在两个平行壁之间，我们通过这两个壁向气体输入热能。我们在此研究当非弹性冷却恰好被某种外部能量输入（随机力或粘性加热）平衡时出现的稳态，从而产生均匀的热通量。基于纳维 - 斯托克斯颗粒流体动力学的分离准则是根据示踪剂扩散传输系数写出的，其对系统参数（质量、尺寸和恢复系数）的依赖性是通过非弹性玻尔兹曼方程的解明确确定的。理论预测通过蒙特卡罗和分子动力学模拟得到验证，结果表明即使在强剪切和/或非弹性条件下，纳维 - 斯托克斯流体动力学也能产生准确的分离准则。
