{
  "abstract": "Motile microorganisms inhabit oscillatory flows encountered in physiological and engineering systems, yet the influence of flow unsteadiness on their shear-induced preferential concentration remains less understood. We investigate transverse transport of elongated microswimmers in oscillatory pressure-driven channel flow using complementary Langevin simulations and two- and one-dimensional Fokker-Planck models. Agreement between particle-based and continuum descriptions across governing parameters establishes the fidelity of the Fokker-Planck formulation for swimmer transport in oscillatory shear flows. Our analysis demonstrates that oscillatory forcing fundamentally modifies classical steady-flow shear-trapping. We find that increasing Womersley number $Wo$ reduces centerline depletion by confining oscillatory shear to thinner near-wall regions. In contrast, increasing frequency ratio $β$, of swimmer rotational diffusion rate and flow oscillation frequency, promotes sustained orientational anisotropy, and leads to a saturating increase in centerline depletion. In the weak-swimming limit, we derive a hierarchy of coupled orientational moments, enabling analytical solutions at arbitrary temporal harmonic order. The asymptotic solutions establish a universal transfer law showing that, for a given swimmer shape, the normalized leading-order orientational response depends solely on $β$. Reconstruction of the orientational distribution yields closed-form expressions for the swimmer concentration profile and depletion index, $I_D$. Our asymptotic solution recovers the steady-flow weak-shear scaling of $I_D$ with flow Peclet number, $Pe_f$, of $I_D \\propto Pe_f^2$, and reveals that oscillatory forcing attenuates this response by a factor $16β^2/(1+16β^2)$. These results provide a theoretical framework to predict transverse transport of microswimmers in oscillatory channel flows.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.06393",
  "author_total": 2,
  "authors": [
    {
      "name": "Raghav Ram"
    },
    {
      "name": "Ashwin Ramachandran"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/79gavg1rxjxfj.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.06393",
  "fulltext_url": null,
  "id": "79gavg1rxjxfj",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.06393",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.bio-ph"
    ],
    [
      "arxiv",
      "physics.flu-dyn"
    ],
    [
      "openalex",
      "3104|Micro and Nano Robotics"
    ]
  ],
  "openalex": "W7212068319",
  "pdf_url": "https://arxiv.org/pdf/2609.06393",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-06",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/79gavg1rxjxfj.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:48Z",
      "native_id": "2609.06393",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.06393"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:physics.bio-ph",
      "subfield": "biological-medical"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.flu-dyn",
      "subfield": "fluid-dynamics"
    }
  ],
  "title": "Transverse transport of microswimmers in oscillatory channel flows",
  "title_text": "Transverse transport of microswimmers in oscillatory channel flows",
  "type": "preprint",
  "updated_at": "2026-10-30T12:19:48Z",
  "url": "https://research.draconitic.com/paper/79gavg1rxjxfj",
  "venue": "arXiv",
  "versions": []
}