Using a code developed to compute high Reynolds number viscoelastic flows, polymer injection from the upstream stagnation point of a circular cylinder is modeled at Re 1⁄4 3900. Polymer stresses are represented using the FENE-P constitutive equations. By increasing polymer injection rates within realistic ranges, significant near wake stabilization is observed. Rather than a turbulent detached ...

Experiments with the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction demonstrate that three-dimensional scroll waves can rotate around filaments that end in the wake of a traveling excitation pulse. The vortex structures nucleate during the collision of three nonrotating excitation pulses. The nucleation process and the wave-termination of filaments are direct consequences of the system's an...

The long-term goals of the research are to investigate the important mechanisms involved in the interaction of current with axisymmetric or cylindrical bodies, which are tethered or free to respond to the fluid forcing. We intend to undertake studies that measure in-line and transverse dynamics and forces, wake vortical motions, and signatures of such bodies undergoing vortex-induced vibrations...

This study discusses hydrodynamic effects of horizontal spoilers fixed on submarine pipelines. Numerical calculations are conducted to investigate the influences of the spoiler on flow profile, vortex shedding frequency, drag coefficients and lift coefficients. The calculation results demonstrate that attached horizontal spoilers could change the wake flow and enhance the self-burial of the pip...

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We illustrate the problem of wake optimization on two examples. In the first example, the destruction of trailing vortices, we show that stochastic optimization is a flexible tool to identify vortex systems enhancing natural instabilities. In the second example, the problem of drag reduction in a cylinder wake, a priori information on the flow dynamics is highly desirable and we give some preli...

Nonlinear responses to a transversely oscillating cylinder in the wake of a stationary upstream cylinder are studied theoretically by using an immersed-boundary method at Re=100. Response states are investigated in the three flow regimes for a tandem-cylinder system: the “vortex suppression” regime, the critical spacing regime, and the “vortex formation” regime. When the downstream cylinder is ...

The function of the heterocercal tail in sharks has long been debated in the literature. Previous kinematic data have supported the classical theory which proposes that the beating of the heterocercal caudal fin during steady horizontal locomotion pushes posteroventrally on the water, generating a reactive force directed anterodorsally and causing rotation around the center of mass. An alternat...

Techniques for Improved Blade Vortex Interaction Modeling,”Proceedings of the 51st Annual Forum of the American Helicopter Society (Fort Worth, TX), 1995. 31Johnson, W., Helicopter Theory, Princeton Univ. Press, Princeton, NJ, 1980, Chap. 1. 32Miller, W., “Analytical/Numerical Matching and Periodic Inversion: Two Advances in Free Wake Analysis,” Ph.D. Dissertation, Dept. of Mechanical Engineeri...

Cl = section lift coefficient c = local chord length D = fading-memory constant G = nondimensional circulation l = section lift force/length m = number of points used in sine series expansion of circulation function N = consecutive iterations convergence parameter r = perpendicular distance from vortex tol = iteration relative tolerance of conversion U1 = freestream velocity magnitude w = downw...