The effect of fluid elasticity on the vortex shedding from a cylinder at low Reynolds numbers
Abstract
Experimental results are presented showing the changes induced by fluid elasticity on the von Kármán vortex street in the wake of a cylinder placed normal to a uniform oncoming flow. The elastic fluids used are dilute aqueous polymer solutions of polyethylene oxide with a high molecular weight of about 10^6g/mol. The solutions, which are considered to have a constant shear viscosity, are characterized rheologically to quantify their elastic properties. LDA, PIV and hydrogen wire techniques are used to study the wake dynamics at Reynolds numbers in the range 50-150 and low Deborah numbers of the order of 0.1. A combination of endplates and ``end-cylinders'' is used to induce parallel shedding, i.e. to obtain quasi-2D conditions. A critical Reynolds - Deborah number relationship is established, illustrating the combined effects of elasticity and inertia on the stability of the cylinder wake. The influence of fluid elasticity on the velocity field and the Strouhal - Reynolds number relationship is also shown.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 2003
- Bibcode:
- 2003APS..DFD.JR007P