This paper delineates experimental and numerical results concerning the effect of the stratification and the tilt on the 3D instabilities of a cylinder wake led at moderate Reynolds numbers from the 2D von Karman vortex street. For a vertical cylinder, shadowgraph visualisations put forward an unstable mode similar to the mode A well known in homogeneous fluids. When the cylinder is tilted a ne...

A von Karman vortex street generated in the usual way was subjected to a deceleration, thereby changing the ratio of longitudinal to lateral spacing between the vortices. Distortion of the individual vortices followed which resulted in annihilation of concentrated vortex regions and creation of a stationary wake flow. This wake flow was itself dynamically unstable and developed into a new vorte...

To control the Karman vortex street formed behind a thin airfoil at a certain incidence, a control cylinder was placed at the suction side apart from the airfoil in the downstream region. Both smoke visualization and hot-wire measurements confirmed that the Karman vortex street was completely suppressed. The mechanism for suppression of the vortex street was examined with a hot-wire survey.

Introduction. The Karman-vortex street formed behind two-dimensional bluff bodies has attracted interest because of its beautiful flow pattern. It goes without saying that this beautifulness results from the alternative vortices regularly shed from the body. Vortex shedding induces aerodynamic force perpendicular to the mean flow. This force causing mechanical vibration of the model is accompan...

The stability to three-dimensional disturbances of three classical steady vortex configurations in an incompressible inviscid fluid is studied in the limit of small vortex cross-sectional area and long axial disturbance wavelength. The configurations examined are the single infinite vortex row, the Karman vortex street of staggered vortices and the symmetric vortex street. It is shown that the ...

We perform numerical experiments with a novel cellularautomaton fluid model. The model has simple pair-interaction rules and works in arbitrarily many dimensions; here we consider the twodimensional case. By observing the smoothing-out of the velocity profile of a shear flow and the relaxation of a shear wave, we measure the kinematic shear viscosity and obtain a value of :::::: 0.5. To demonst...

Different models of self-excited oscillators which are four-dimensional extensions of the van der Pol system are reported. Their symmetries are analyzed. Three of them were introduced to model the release of vortices behind circular cylinders with a possible transition from a symmetric to an antisymmetric Bénard-von Karman vortex street. The fourth reported self-excited oscillator is a new mode...

In this paper, the lateral line trunk canal (LLTC) of a fish is modeled to investigate how it is affected by an external flow field. Potential flow theory is adopted to model the flow field around a fish's body in the presence of a Karman vortex street. Karman and reverse Karman streets represent the flow patterns behind a bluff body and a traveling fish, respectively. An analytical solution is...

An inviscid model for the Karman vortex street, containing vortices of uniform vorticity surrounded by irrotational fluid, is related to the wake behind a bluff body by a global analysis requiring the conservation of momentum, energy and vorticity. Some comparison is made with experimental results reported in the literature. A qualitative procedure is proposed whereby the slow evolution of the ...