Thermal collapse of a granular gas under gravity.
Free cooling of a gas of inelastically colliding hard spheres represents a central paradigm of kinetic theory of granular gases. At zero gravity the temperature of a freely cooling homogeneous granular gas follows a power law in time. How does gravity, which brings inhomogeneity, affect the cooling? We combine molecular dynamics simulations, a numerical solution of hydrodynamic equations and an analytic theory to show that a granular gas cooling under gravity undergoes thermal collapse: it cools down to zero temperature and condenses on the bottom of the container in a finite time.
Volfson
Dmitri
D
Bioengineering Department, University of California, San Diego, La Jolla, California 92093-0402, USA.
Meerson
Baruch
B
Tsimring
Lev S
LS