Development of the Wake Behind a Circular Cylinder Impulsively Started into Rotatory and Rectilinear Motion: Intermediate Rotation Rates
Abstract
Temporal development of 2-D viscous incompressible flow generated by a circular cylinder started impulsively into steady rotatory and rectilinear motion is studied by integrating a velocity/vorticity formulation of the governing equations, using an explicit finite-difference/pseudo-spectral technique and a new implementation of the Biot-Savart law. Results are presented for a Reynolds number of 200 (based on the cylinder diameter 2a and magnitude U of the rectilinear velocity) for several values of the angular/rectilinear speed ratio alpha = Omega(a)/u (where Omega is the angular speed) up to 3.25. For values of alpha > or = 1, our extension of the computations to larger dimension less times than those possible in the 1985 experimental work of Coutanceau & Menard or considered in the 1985 computational work of Badr & Dennis allows a more complete discussion of the long-term wake development. Several new kinematic and dynamic aspects are also discussed. For higher values of alpha, our results indicate that for Re = 200, vortex shedding does indeed occur for alpha = 3.25 (and possibly for higher value of alpha also), in contrast to the conclusion of Coutanceau & Menard. The shedding process is however, very different from that which gives rise to the usual Karman vortex street for alpha = 0. Consecutive vortices shed by the body can be shed from the same side, and be of the same sense, in contrast to the nonrotating case. Implications of the results are discussed in terms of the possibly of suppressing vortex shedding by open- or closed-loop rotation rate control.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA233295
Entities
People
- Arne J. Pearlstein
- Yen-ming Chen
- Yuh-roung Ou