Experimental study of quasi two-dimensional granular gases in microgravity
Abstract
We revisit the properties of quasi two-dimensional mono-disperse granular gases under micro-gravity conditions using an air table. The air flow provides a microgravity-like environment and homogeneously injects energy into the system. The energy supplied to the particles is dissipated through aerodynamic drag and by collisions between particles, thus leading to a steady state. The horizontal components of the translational velocity and the vertical component of the angular velocity of the particles are found to follow remarkably well Gaussian distributions except at very low surface fraction. We independently varied the particle size , the surface coverage , and the air flow speed , and found that the variation of the mean square horizontal velocity of the particles can be well described by a simple scaling law: < 2 > proportional to 0.4-0.25-0.65. Importantly, the dependence of the scaling exponents on and can be inferred from the kinetic theory of granular gases, combined with the experimental determination of the collisional friction coefficient and the normal restitution coefficient in particle-particle collisions. Additionally, we show that the power injected per particle by the air flow is independent of the surface coverage and particle size. solely depends on the air flow speed as proportional to 0.6. Interestingly, our quasi 2D granular system behaves similarly to a twodimensional gas of hard disks and the measured mean free path and self-diffusion coefficient agree perfectly with the prediction of the kinetic theory. However, the analysis of the rotational granular temperature of this two-dimensional gas indicates that it is much smaller than its translational granular temperature , and that energy equipartition between translational and rotational degrees of freedom is therefore not satisfied.
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BibTeX
@article{sadah2026experimental,
title = {{Experimental study of quasi two-dimensional granular gases in microgravity}},
author = {Rawad Sadah and Renaud Delannay and Alexandre Valance},
journal = {Mechanics Research Communications},
year = {2026},
month = jun,
doi = {10.1016/j.mechrescom.2026.104752},
url = {https://hal.science/hal-05766823v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Experimental study of quasi two-dimensional granular gases in microgravity
AU - Rawad Sadah
AU - Renaud Delannay
AU - Alexandre Valance
PY - 2026
DA - 2026/06/16
JO - Mechanics Research Communications
DO - 10.1016/j.mechrescom.2026.104752
UR - https://hal.science/hal-05766823v1
AB - We revisit the properties of quasi two-dimensional mono-disperse granular gases under micro-gravity conditions using an air table. The air flow provides a microgravity-like environment and homogeneously injects energy into the system. The energy supplied to the particles is dissipated through aerodynamic drag and by collisions between particles, thus leading to a steady state. The horizontal components of the translational velocity and the vertical component of the angular velocity of the particles are found to follow remarkably well Gaussian distributions except at very low surface fraction. We independently varied the particle size , the surface coverage , and the air flow speed , and found that the variation of the mean square horizontal velocity of the particles can be well described by a simple scaling law: < 2 > proportional to 0.4-0.25-0.65. Importantly, the dependence of the scaling exponents on and can be inferred from the kinetic theory of granular gases, combined with the experimental determination of the collisional friction coefficient and the normal restitution coefficient in particle-particle collisions. Additionally, we show that the power injected per particle by the air flow is independent of the surface coverage and particle size. solely depends on the air flow speed as proportional to 0.6. Interestingly, our quasi 2D granular system behaves similarly to a twodimensional gas of hard disks and the measured mean free path and self-diffusion coefficient agree perfectly with the prediction of the kinetic theory. However, the analysis of the rotational granular temperature of this two-dimensional gas indicates that it is much smaller than its translational granular temperature , and that energy equipartition between translational and rotational degrees of freedom is therefore not satisfied.
SN - 0093-6413
ER -