A CONTRIBUTION TO FLOW-SEPARATION PROBLEM IN UNSTEADY MOTION OF A BODY

Roll motion is the least predictable of ship motions, largely because of viscosity effects, which in turn causes flow separations to occur. As a result of these phenomena, roll damping is often highly nonlinear. It is best estimated in the present state of the art by strictly empirical methods. In this report, several relevant flow-separation problems are studied from a fundamental point of view. These are divided generally into two categories: (1) boundary-layer separation and (2) sharp-edge separation. In both cases, starting motion and oscillatory motion are considered separately. Emphasis is placed on rather simple methods of calculations. Results are compared with experiments and/or more detailed calculation methods wherever such are available. Finally, a procedure is proposed (but not carried out) for treating the formation of vortex sheets by a translating rolling ship hull. (Author)

• Corporate Authors:

  University of Michigan, Ann Arbor

  Department of Naval Architects and Marine Engineers
  Ann Arbor, MI  United States  48109
• Authors:
  • Himeno, Y
• Publication Date: 1979-7

Media Info

• Pagination: 46 p.

Subject/Index Terms

• TRT Terms: Boundary layer flow; Boundary layer separation; Curvature; Damping (Engineering); Damping (Physics); Hulls; Mathematical models; Moments (Mechanics); Oscillation; Rolling; Ship motion; Starting (Driving); Unsteady flow; Viscosity; Vortex shedding; Vortices
• Uncontrolled Terms: Ship hulls; Starting
• Old TRIS Terms: Curved profiles; Roll; Roll damping; Rolling moment; Vortex theory
• Subject Areas: Marine Transportation; Vehicles and Equipment;

Filing Info

• Accession Number: 00326083
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: 220 Final Rpt.
• Contract Numbers: N00014-79-C-0244
• Files: TRIS
• Created Date: Nov 19 1981 12:00AM