{ "id": "2410.07448", "version": "v1", "published": "2024-10-09T21:29:55.000Z", "updated": "2024-10-09T21:29:55.000Z", "title": "On the Propulsion of a Rigid Body in a Viscous Liquid Under the Action of a Time-Periodic Force", "authors": [ "Mher M. Karakouzian", "Giovanni P. Galdi" ], "categories": [ "math.AP" ], "abstract": "A rigid body $\\mathcal{B}$ moves in an otherwise quiescent viscous liquid filling the whole space outside $\\mathcal{B}$, under the action of a time-periodic force $\\boldsymbol{\\mathsf{f}}$ of period $T$ applied to a given point of $\\mathcal{B}$ and of fixed direction. We assume that the average of $\\boldsymbol{\\mathsf{f}}$ over an interval of length $T$ does not not vanish, and that the amplitude, $\\delta$, of $\\boldsymbol{\\mathsf{f}}$ is sufficiently small. Our goal is to investigate when $\\mathcal{B}$ executes a non-zero net motion; that is, $\\mathcal{B}$ is able to cover any prescribed distance in a finite time. We show that, at the order $\\delta$, this happens if and only if $\\boldsymbol{\\mathsf{f}}$ and $\\mathcal{B}$ satisfy a certain condition. We also show that this is always the case if $\\mathcal{B}$ is prevented from spinning. Finally, we provide explicit examples where the condition above is satisfied or not. All our analysis is performed in a general class of weak solutions to the coupled system body-liquid problem.", "revisions": [ { "version": "v1", "updated": "2024-10-09T21:29:55.000Z" } ], "analyses": { "keywords": [ "rigid body", "time-periodic force", "propulsion", "coupled system body-liquid problem", "non-zero net motion" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }