Magnetically heated granular gas in a low-gravity environment

Peidong Yu,Matthias Schröter,Masato Adachi,Matthias Sperl,M.A Aguirre,R Soto,L.A Pugnaloni,S Luding

doi:10.1051/epjconf/202124904002

Abstract

Magnetic forces are used to heat up thousands of spherical particles under low-gravity. This long range external excitation, combined with the induced particle-particle interactions, results in a homogeneous spatial distribution of the particles. Comparisons with predictions of kinetic theories can hence be carried out. Haff’s cooling law is verified qualitatively, while the measured cooling time scale is quantitatively different from the prediction. The high velocity tail of the velocity distribution during homogeneous cooling state (HCS) is measured, while the expected cluster formation after HCS can not be verified by our experiment.

Highlights

Based on a homogeneously heated granular gas system, our goals are to verify three important predictions ofFor kinetic theories, one great challenge posed by gran- kinetic theories for dissipative gases
The reproducibility of the experiments is demonstrated when comparing the product of the two fitted parameters v0 · τ, which is determined by system properties, from the first experiment with those from the other three
Haff’s law can qualitatively well describe the cooling behaviour of our system, the quantitative difference between τk.t. from kinetic theory and τ from experiment is more than 250%

Summary

Introduction

Based on a homogeneously heated granular gas system, our goals are to verify three important predictions ofFor kinetic theories, one great challenge posed by gran- kinetic theories for dissipative gases. After the exular gases is the energy dissipation through particle col- ternal heating is turned off, the system is expected to mainlisions. The focus on dealing with this dissipative term tain its homogeneity but cools down because the energy often leads to simplifying assumptions of other terms that loss is no longer compensated. The cooling behaviour of can complicate the dynamical equations [1]. One such im- this homogeneously cooling state (HCS) is described by: portant assumption, the spatial homogeneity of the particles, though straightforwardly achievable by simulations [2, 3] when the periodic boundary condition is adopted, inv(t) = v0(1 + t/τ)γ, (1). Haff in 1983, using hydrodynamic periment into a low-gravity environment [5, 6], such as a methods, first proposed this algebraic decaying behaviour parabolic flight, the drop tower, or a sounding rocket

Objectives

Methods

Results

Conclusion