Experimental and numerical study on energy dissipation in freely cooling granular gases under microgravity

Abstract

Energy dissipation is one of the most important properties of granular gas, which makes its behavior different from that of molecular gas. In this work we report our investigations on the freely-cooling evolution of granular gas under microgravity in a drop tower experiment, and also conduct the molecular dynamics (MD) simulation for comparison. While our experimental and simulation results support Haff's law that the kinetic energy dissipates with time t as E(t) ∼ (1 + t/τ) −2 , we modify τ by taking into account the friction dissipation during collisions, and study the effects of number density and particle size on the collision frequency. From the standard deviation of the measured velocity distributions we also verify the energy dissipation law, which is in agreement with Haff's kinetic energy dissipation.

Sub-anomalous diffusion and unusual velocity distribution evolution in cooling granular gases: theory

“…These results agree quantitatively well with existing numerical and experimental reports [22][23][24][25][26][27][28] on the decay of the mean velocity (eq. ( 2)) and the drop in the kinetic energy (eq.…”

Parametric study of the clustering transition in vibration driven granular gas system*

“…4(b), the characteristic cooling time is plotted as a function of ε. We have modified Haff's time by adding a friction term γ to make the time τ H given by [6] τ…”

“…Therefore, it is necessary to conduct experimental study of the granular gas behavior either under microgravity [4,5] or by computer simulation. [6,7] In a pioneering experiment, cluster forming in granular gas was reported by Falcon et al [8] The system was mechanically driven into a steady-state by shaker to balance the internal energy dissipation. Clustering occurred when the global volume fraction φ g exceeded a critical value, resulting in a decrease in both pressure and kinetic temperature.…”

Characteristics of a Magnetic Bulk Thermostat for Granular Gas Investigations in Microgravity

“…Thus, the investigations have been carried out thoroughly by simulations (Cafiero et al , 2002Kang et al 2010;Li et al 2011;Miller and Luding 2004;Mitrano et al 2012;Rubio-Largo et al 2016), while several experimental investigations have been performed in microgravity platforms e.g. drop tower, parabolic flight, sounding rocket, and magnetic levitation, where particles were excited by means of mechanical-boundary shaking or magnetic force (Aumaître et al 2018;Evesque et al 2005;Falcon et al 1999Falcon et al , 2013Harth et al 2013;Hou et al 2008;Maaß et al 2008;Olafsen and Urbach 1998;Rouyer and Menon 2000;Sack et al 2013;Wang et al 2018;Yu et al 2019). In addition, an analytical method for granular gas investigations was developed aided by machine learning technique to evaluate structural and dynamic properties of the particles (Puzyrev et al 2020).…”