{
  "id": "2402.12553",
  "version": "v2",
  "published": "2024-02-19T21:23:00.000Z",
  "updated": "2024-06-18T18:36:21.000Z",
  "title": "Triglobal resolvent-analysis-based control of separated flows around low-aspect-ratio wings",
  "authors": [
    "Jean Hélder Marques Ribeiro",
    "Kunihiko Taira"
  ],
  "categories": [
    "physics.flu-dyn"
  ],
  "abstract": "We perform direct numerical simulations (DNS) of actively controlled laminar separated wakes around low-aspect-ratio wings with two primary goals: (i) reducing the size of the separation bubble and (ii) attenuating the wing tip vortex. Instead of preventing separation, we modify the three-dimensional ($3$-D) dynamics to exploit wake vortices for aerodynamic enhancements. A direct wake modification is considered using optimal harmonic forcing modes from triglobal resolvent analysis. For this study, we consider wings at angles of attack of $14^\\circ$ and $22^\\circ$, taper ratios $0.27$ and $1$, and leading edge sweep angles of $0^\\circ$ and $30^\\circ$, at a mean-chord-based Reynolds number of $600$. The wakes behind these wings exhibit $3$-D reversed-flow bubble and large-scale vortical structures. For tapered swept wings, the diversity of wake vortices increases substantially, posing a challenge for flow control. To achieve the first control objective for an untapered unswept wing, root-based actuation at the shedding frequency is introduced to reduce the reversed-flow bubble size by taking advantage of the wake vortices to significantly enhance the aerodynamic performance of the wing. For both untapered and tapered swept wings, root-based actuation modifies the stalled flow, reduces the reversed-flow region, and enhances aerodynamic performance by increasing the root contribution to lift. For the goal of controlling the tip vortex, we demonstrate the effectiveness of actuation with high-frequency perturbations near the tip. This study shows how insights from resolvent analysis for unsteady actuation can enable global modification of $3$-D separated wakes and achieve improved aerodynamics of wings.",
  "revisions": [
    {
      "version": "v2",
      "updated": "2024-06-18T18:36:21.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "triglobal resolvent-analysis-based control",
      "low-aspect-ratio wings",
      "separated flows",
      "controlled laminar separated wakes",
      "wake vortices"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 0,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}