## Abstract

The dynamics of rapid granular flows is governed by dissipative

interactions of particles with each other and with the system walls. To adequately describe these interactions, roughness and particle shape must be

taken into account. The coefficient of restitution for arbitrary particles thus

depends not only on material properties and impact velocity but also on the

angular orientation at the instant of the collision. By measurements of the

coefficient of restitution from the sound signal emitted by a sphere bouncing

repeatedly off the ground, it was found that small deviations from the perfect shape of the sphere lead to large measurement errors. Using stochastic

methods, the effective coefficient of restitution for the collision of a rough

sphere with a plane was described as a fluctuating quantity, characterized by

a rather uncommon probability density function. It was shown that modelling

the coefficient of restitution as a stochastic variable significantly affects the

dynamics of particles under rapid granular flows. The decay of temperature

of rapid granular flows in the homogeneous cooling state deviates from Haff’s law for gases of particles interacting via a constant coefficient of restitution

also from the scaling law for gases of viscoelastic particles.

interactions of particles with each other and with the system walls. To adequately describe these interactions, roughness and particle shape must be

taken into account. The coefficient of restitution for arbitrary particles thus

depends not only on material properties and impact velocity but also on the

angular orientation at the instant of the collision. By measurements of the

coefficient of restitution from the sound signal emitted by a sphere bouncing

repeatedly off the ground, it was found that small deviations from the perfect shape of the sphere lead to large measurement errors. Using stochastic

methods, the effective coefficient of restitution for the collision of a rough

sphere with a plane was described as a fluctuating quantity, characterized by

a rather uncommon probability density function. It was shown that modelling

the coefficient of restitution as a stochastic variable significantly affects the

dynamics of particles under rapid granular flows. The decay of temperature

of rapid granular flows in the homogeneous cooling state deviates from Haff’s law for gases of particles interacting via a constant coefficient of restitution

also from the scaling law for gases of viscoelastic particles.

Original language | English |
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Title of host publication | Particles in Contact |

Subtitle of host publication | Micro Mechanics, Micro Process Dynamics and Particle Collective |

Editors | Sergiy Antonyuk |

Publisher | Springer |

ISBN (Electronic) | 978-3-030-15899-6 |

ISBN (Print) | 978-3-030-15898-9 |

Publication status | Published - 2019 |