{
  "id": "2212.02188",
  "version": "v1",
  "published": "2022-12-05T11:50:48.000Z",
  "updated": "2022-12-05T11:50:48.000Z",
  "title": "Investigating the Origins of Fluctuation Forces in Homogeneous Isotropic Turbulence",
  "authors": [
    "Daniel Putt",
    "Rodolfo Ostilla-Mónico"
  ],
  "categories": [
    "physics.flu-dyn"
  ],
  "abstract": "A net force can arise on objects which lie in systems with complex energy partitions, even if the system is on average stationary. These forces are usually called fluctuation forces, as they arise due to the objects modifying the character of the fluctuations within the system. We continue the investigation of Spandan \\emph{et al.}, \\textit{Sci. Adv., 6(14), eaba0461} (2020), who found an attractive fluctuation force between two parallel plates in homogeneous isotropic turbulence (HIT). By conducting simulations which systematically vary the plate size, and Reynolds number, we confirm the two-fold origin of the force in HIT: the plates restrict the presence of energy structures in the slit, and pack intense vortical structures which stretch each other causing the pressure to drop. At $Re_\\lambda=100$, we find that small plates cannot effectively pack structures, and this causes the force to behave in a monotonic manner, with a maximum force for the smallest plate separations. Medium and large plates show a non-monotonic behaviour of the force with plate distance consistent with earlier studies, demonstrating that if the plates are large enough to pack structures their size is not an important determinant of the force. By decreasing $Re_\\lambda$, we show that removing vortex stretching decreases the attractive force, but does not completely eliminate it, and that the non-monotonic character of the force is due to vortex stretching. These results support the two-fold origin of the force, while shedding further light on the mechanisms that generate it.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2022-12-05T11:50:48.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "homogeneous isotropic turbulence",
      "fluctuation force",
      "two-fold origin",
      "pack structures",
      "plate distance consistent"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}