## What is/are Granular Gas?

Granular Gas - A system of differential equations of sunflower seeds motions, as a granular gas, under the action of a vibrating surface was developed, taking into account the elastic-damping interaction and physical and mechanical properties of seeds.^{[1]}Granular gases are interesting multiparticle systems which, irrespective of the apparent simplicity of particle interactions, exhibit a rich scenario of so far only little understood features.

^{[2]}We apply shadow-based and feature-tracking methods to analyze the dynamics of granular gases in a container with vibrating side walls under microgravity.

^{[3]}We demonstrate the operation of the device by analyzing the three-dimensional packing of particles (tomograms) and structure formation in a granular gas under periodic excitation (radiograms).

^{[4]}Some classical and modern instances of applications are: molecules in gases, electron transport in semiconductor materials, ions and electrons in plasmas, grains or beads in granular gases, stars or galaxies in astrophysics, endothelial cells in chemotactic movement for angiogenesis, neurons spike dynamics in neuroscience, fuel droplets in Diesel engines, dust particles in atmospheric pollution, animals in a swarm, agents in an economic market, pedestrians strolling around complex building geometries.

^{[5]}The present chapter provides a concise introduction to the kinetic theory of granular gases (namely, gases of hard spheres with inelastic collisions) at low and moderate densities.

^{[6]}We consider two popular models derived from the theory of granular gases.

^{[7]}Transport properties of granular gases driven by a stochastic bath with friction are determined.

^{[8]}However, the collective effects of Coulomb forces on the nonequilibrium dynamics and aggregation process in a granular gas – a model representative of the above physical processes – have so far evaded theoretical scrutiny.

^{[9]}In this paper, we propose a simple fast Fourier spectral method for the inelastic Boltzmann collision operator, with its application to one of the widely used models of granular gases, the inelastic Boltzmann equation with a heating source.

^{[10]}Energy dissipation is one of the most important characteristics of granular gas, which makes its behavior different from that of molecular gas.

^{[11]}Granular material is subjected to intense vibration, transferring it into the state of a “granular gas” before separation.

^{[12]}This chapter addresses the study of non-Newtonian transport properties of several steady laminar flows in granular gases.

^{[13]}

## homogeneous cooling state

Conditions for the stability under linear perturbations around the homogeneous cooling state are studied for dilute granular gases of inelastic and rough hard disks or spheres with constant coefficients of normal (α) and tangential (β) restitution.^{[1]}A normal solution to the revised Enskog kinetic theory of smooth monocomponent granular gases is obtained via the Chapman–Enskog method for states close to the local homogeneous cooling state.

^{[2]}A homogeneous state, akin to the homogeneous cooling state of granular gases, is seen to arise and the singular behavior of both the collisions and the precollisional correlations are highlighted.

^{[3]}This chapter deals with the problem of the so-called homogeneous cooling state (namely, a homogeneous state where granular temperature monotonically decays in time) for mono- and multicomponent granular gases.

^{[4]}

## Dilute Granular Gas

Conditions for the stability under linear perturbations around the homogeneous cooling state are studied for dilute granular gases of inelastic and rough hard disks or spheres with constant coefficients of normal (α) and tangential (β) restitution.^{[1]}The transport coefficients for dilute granular gases of inelastic and rough hard disks or spheres with constant coefficients of normal (α) and tangential (β) restitution are obtained in a unified framework as functions of the number of translational (d_{t}) and rotational (d_{r}) degrees of freedom.

^{[2]}We numerically and theoretically investigate how the softness of particles affects the rheology of sheared dilute granular gases.

^{[3]}This paper presents an analytical study of the Riemann problem for dilute granular gas using initial conditions that result in a shock–contact–shock wave structure.

^{[4]}Inelastic Maxwell models for dilute granular gases are introduced in this chapter.

^{[5]}The direct simulation Monte Carlo method has been used to simulate dilute granular gases 1-3, where collisions between particles are uncorrelated and molecular chaos assumptions are valid.

^{[6]}

## Monocomponent Granular Gas

The GDH-theory extends to granular mixtures the results derived years ago for monocomponent granular gases by established kinetic theory models.^{[1]}A normal solution to the revised Enskog kinetic theory of smooth monocomponent granular gases is obtained via the Chapman–Enskog method for states close to the local homogeneous cooling state.

^{[2]}The study is carried out for monocomponent granular gases and binary granular mixtures in the tracer limit.

^{[3]}

## Multicomponent Granular Gas

In general, the total kinetic energy in a multicomponent granular gas of inelastic and rough hard spheres is unequally partitioned among the different degrees of freedom.^{[1]}This chapter deals with the problem of the so-called homogeneous cooling state (namely, a homogeneous state where granular temperature monotonically decays in time) for mono- and multicomponent granular gases.

^{[2]}

## Coupled Granular Gas

The experimental setup consists in two coupled granular gas nonequilibrium steady-state (NESS) heat baths, in which Brownian-like rotors are imbedded.^{[1]}The experimental set-up consists in two coupled granular gas Non-Equilibrium Steady State (NESS) heat baths, in which Brownian-like rotors are imbedded.

^{[2]}

## Dimensional Granular Gas

A model for continuous-opinion dynamics is proposed and studied by taking advantage of its similarities with a mono-dimensional granular gas.^{[1]}A linear stability analysis of the hydrodynamic equations of a model for confined quasi-two-dimensional granular gases is carried out.

^{[2]}

## Heated Granular Gas

experimentally explored the steady state dynamics of a heated granular gas of rod-like particles in microgravity [K.^{[1]}We analyze the linear response properties of the uniformly heated granular gas.

^{[2]}

## granular gas bubble

The comparison of recrystallization kinetics obtained from experiments and modeling suggests that the interstitial loop accumulation leads to the recrystallization and the interstitial loop growth is suppressed inside coarse grains due to the over-pressured intra-granular gas bubbles.^{[1]}Especially, intragranular and intergranular gas bubbles will make the fuel meat evolve into a porous structure, and the fuel porosity and pore pressure will change continuously with the irradiation time.

^{[2]}