Suppression of Vortex Shedding from a Hemisphere by the Addition of a Porous Coating

Details

• Personal Author:
  Jena, Satyasreet ; Turkevich, Leonid A. ; Jog, Milind A. ; Ghia, Urmila
• Description:
  Vortex shedding from a bluff body may be suppressed (via a mechanism not fully understood) by coating the body with a porous layer of solid particles. The porous layer alters the boundary layer near the surface of the bluff body, allowing for a more extended transition from no slip at the body surface to the free stream flow; this expansion of the flow profile may be sufficient to stabilize fluctuations in the boundary layer. This may be advantageous in engineering applications where there is a need to reduce aerodynamic forces and acoustic vibrations produced by the fluctuating pressure fields of vortex shedding. The current study aims to understand the role of the porous layer in suppressing vortex shedding for a hemisphere mounted on a substrate. The simulations are conducted at (hemisphere radius) Reynolds number 10,000. The porous layer is simulated by introducing Lagrangian multiphase solid particles with very high density, arranged as hemispherical shells around the solid dome. The porosity of the layer is controlled by varying the particle diameter, while the thickness of the coating is varied by successively adding shell layers. The simulations are conducted under zero gravitational acceleration; thus, the Lagrangian particles do not settle, but their infinite inertia precludes their being set in motion by the fluid. Adding a 1-layer shell with 70% porosity significantly reduces the vorticity oscillations at the apex of the hemisphere; at two layers, vortex shedding is eliminated. At increased coating porosity, vortex shedding may still be suppressed with additional coating thickness.
• Subjects:
  Occupational Health Safety
• Keywords:
  Author Keywords: Vortex Shedding; Porous Coating; Turbulent Flow Fluid Mechanics; Coatings; Porous Materials; Engineering;
• Source:
  Proceedings of the ASME 2025 International Mechanical Engineering Congress and Exposition (IMECE 2025), November 16-20, 2025, Memphis, Tennessee. Volume 7: Engineering Education; Fluids Engineering. New York: The American Society of Mechanical Engineers, paper no. IMECE2025-165609, 2025 Nov; 7:V007T11A024
• ISBN:
  9780791889381
• Publisher:
  The American Society of Mechanical Engineers
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  Ohio ; Chicago Region [OSHA]
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DFSE - Division of Field Studies and Engineering
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  7 pdf pages
• Volume:
  7
• NIOSHTIC Number:
  nn:20071473
• Federal Fiscal Year:
  2026
• Peer Reviewed:
  False
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:e4cc9718229b929a49510e364c75e8f9f648a703a9aa25d50515d13aa35810008ae76477d899a3f8a4ec79a66f0e6d1eae1e61767a7bc076147943cdc0101f41
• Download URL:
  https://stacks.cdc.gov/view/cdc/259071/cdc_259071_DS1.pdf
• File Type:
  [PDF - 1.42 MB ]