### Abstract

Original language | English |
---|---|

Article number | 174508 |

Number of pages | 5 |

Journal | Physical Review B: Condensed Matter and Materials Physics |

Volume | 77 |

Issue number | 17 |

DOIs | |

Publication status | Published - 12 May 2008 |

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### Keywords

- mathematical models
- thermal counterflow turbulence

### Cite this

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**Motion of a spherical solid particle in thermal counterflow turbulence.** / Kivotides, Demosthenes.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Motion of a spherical solid particle in thermal counterflow turbulence

AU - Kivotides, Demosthenes

PY - 2008/5/12

Y1 - 2008/5/12

N2 - With numerical methods, we formulate and solve a mathematical model of solid-particle motion in thermal counterflow turbulence. We find a direct link between the intensity of vortex-particle collision induced Kelvin waves (vortex-gas "temperature") and the intensity of the particle-velocity fluctuations around its mean value. The latter mean value is determined by three factors: (a) the frequency of head-on particle-vortex collisions, (b) the formation of a vortex-tail behind the particle, and (c) the viscous drag. The frequency of head-on particle-vortex collisions depends on (a) the vortex line density, (b) the average tangle drift relative to the particle, and (c) the degree of tangle stratification normal to the counterflow direction. A higher stratification degree reduces the frequency of head-on collisions and allows the vortex-tail effect to dominate. At T=1.3 K, vortex voids in the tangle act like barriers to particle motion; the particle-velocity fluctuations are comparable to its mean value and, thus, the particle's direction of motion is sporadically reversed.

AB - With numerical methods, we formulate and solve a mathematical model of solid-particle motion in thermal counterflow turbulence. We find a direct link between the intensity of vortex-particle collision induced Kelvin waves (vortex-gas "temperature") and the intensity of the particle-velocity fluctuations around its mean value. The latter mean value is determined by three factors: (a) the frequency of head-on particle-vortex collisions, (b) the formation of a vortex-tail behind the particle, and (c) the viscous drag. The frequency of head-on particle-vortex collisions depends on (a) the vortex line density, (b) the average tangle drift relative to the particle, and (c) the degree of tangle stratification normal to the counterflow direction. A higher stratification degree reduces the frequency of head-on collisions and allows the vortex-tail effect to dominate. At T=1.3 K, vortex voids in the tangle act like barriers to particle motion; the particle-velocity fluctuations are comparable to its mean value and, thus, the particle's direction of motion is sporadically reversed.

KW - mathematical models

KW - thermal counterflow turbulence

UR - http://www.scopus.com/inward/record.url?scp=43549104902&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.77.174508

DO - 10.1103/PhysRevB.77.174508

M3 - Article

VL - 77

JO - Physical Review B: Condensed Matter and Materials Physics

JF - Physical Review B: Condensed Matter and Materials Physics

SN - 1098-0121

IS - 17

M1 - 174508

ER -