Homogeneous cooling state of frictionless rod particles

S.M. Rubio-Largo, F. Alonso-Marroquin, Thomas Weinhart, R.C. Hidalgo

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

Abstract

In this work, we report some theoretical results on granular gases consisting of frictionless 3D rods with low energy dissipation. We performed simulations on the temporal evolution of soft spherocylinders, using a molecular dynamics algorithm implemented on GPU architecture. A homogeneous cooling state for rods, where the time dependence of the system’s intensive variables occurs only through a global granular temperature, has been identified. We have found a homogeneous cooling process, which is in excellent agreement with Haff’s law, when using an adequate rescaling time τ(ξ)τ(ξ), the value of which depends on the particle elongation ξξ and the restitution coefficient. It was further found that scaled particle velocity distributions remain approximately Gaussian regardless of the particle shape. Similarly to a system of ellipsoids, energy equipartition between rotational and translational degrees of freedom was better satisfied as one gets closer to the elastic limit. Taking advantage of scaling properties, we have numerically determined the general functionality of the magnitude Dc(ξ)Dc(ξ), which describes the efficiency of the energy interchange between rotational and translational degrees of freedom, as well as its dependence on particle shape. We have detected a range of particle elongations (1.5<ξ<4.01.5<ξ<4.0), where the average energy transfer between the rotational and translational degrees of freedom results greater for spherocylinders than for homogeneous ellipsoids with the same aspect ratio.
Original languageEnglish
Pages (from-to)477-485
Number of pages9
JournalPhysica A
Volume443
DOIs
Publication statusPublished - 1 Feb 2016

Fingerprint

Cooling
rods
cooling
degrees of freedom
Degree of freedom
Ellipsoid
ellipsoids
Elongation
elongation
equipartition theorem
Granular Gases
Equipartition
Dynamic Algorithms
Rescaling
Time Dependence
Energy Transfer
Energy Dissipation
Velocity Distribution
Energy
Molecular Dynamics

Keywords

  • METIS-314857
  • IR-99068

Cite this

Rubio-Largo, S. M., Alonso-Marroquin, F., Weinhart, T., & Hidalgo, R. C. (2016). Homogeneous cooling state of frictionless rod particles. Physica A, 443, 477-485. https://doi.org/10.1016/j.physa.2015.09.046
Rubio-Largo, S.M. ; Alonso-Marroquin, F. ; Weinhart, Thomas ; Hidalgo, R.C. / Homogeneous cooling state of frictionless rod particles. In: Physica A. 2016 ; Vol. 443. pp. 477-485.
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Rubio-Largo, SM, Alonso-Marroquin, F, Weinhart, T & Hidalgo, RC 2016, 'Homogeneous cooling state of frictionless rod particles' Physica A, vol. 443, pp. 477-485. https://doi.org/10.1016/j.physa.2015.09.046

Homogeneous cooling state of frictionless rod particles. / Rubio-Largo, S.M.; Alonso-Marroquin, F.; Weinhart, Thomas; Hidalgo, R.C.

In: Physica A, Vol. 443, 01.02.2016, p. 477-485.

Research output: Contribution to journalArticleAcademicpeer-review

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N2 - In this work, we report some theoretical results on granular gases consisting of frictionless 3D rods with low energy dissipation. We performed simulations on the temporal evolution of soft spherocylinders, using a molecular dynamics algorithm implemented on GPU architecture. A homogeneous cooling state for rods, where the time dependence of the system’s intensive variables occurs only through a global granular temperature, has been identified. We have found a homogeneous cooling process, which is in excellent agreement with Haff’s law, when using an adequate rescaling time τ(ξ)τ(ξ), the value of which depends on the particle elongation ξξ and the restitution coefficient. It was further found that scaled particle velocity distributions remain approximately Gaussian regardless of the particle shape. Similarly to a system of ellipsoids, energy equipartition between rotational and translational degrees of freedom was better satisfied as one gets closer to the elastic limit. Taking advantage of scaling properties, we have numerically determined the general functionality of the magnitude Dc(ξ)Dc(ξ), which describes the efficiency of the energy interchange between rotational and translational degrees of freedom, as well as its dependence on particle shape. We have detected a range of particle elongations (1.5<ξ<4.01.5<ξ<4.0), where the average energy transfer between the rotational and translational degrees of freedom results greater for spherocylinders than for homogeneous ellipsoids with the same aspect ratio.

AB - In this work, we report some theoretical results on granular gases consisting of frictionless 3D rods with low energy dissipation. We performed simulations on the temporal evolution of soft spherocylinders, using a molecular dynamics algorithm implemented on GPU architecture. A homogeneous cooling state for rods, where the time dependence of the system’s intensive variables occurs only through a global granular temperature, has been identified. We have found a homogeneous cooling process, which is in excellent agreement with Haff’s law, when using an adequate rescaling time τ(ξ)τ(ξ), the value of which depends on the particle elongation ξξ and the restitution coefficient. It was further found that scaled particle velocity distributions remain approximately Gaussian regardless of the particle shape. Similarly to a system of ellipsoids, energy equipartition between rotational and translational degrees of freedom was better satisfied as one gets closer to the elastic limit. Taking advantage of scaling properties, we have numerically determined the general functionality of the magnitude Dc(ξ)Dc(ξ), which describes the efficiency of the energy interchange between rotational and translational degrees of freedom, as well as its dependence on particle shape. We have detected a range of particle elongations (1.5<ξ<4.01.5<ξ<4.0), where the average energy transfer between the rotational and translational degrees of freedom results greater for spherocylinders than for homogeneous ellipsoids with the same aspect ratio.

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