Flow Visualization of Longitudinal Vortex Appeared at Vortex Formation of Two-Dimensional Wake

The numerical study of the flow over a two-dimensional cylinder which is symmetrically confined in a plane channel is presented to study the characteristics of vortex shedding. The numerical model has been established using direct numerical simulation (DNS) based on the open source computational fluid dynamics (CFD) code named OpenFOAM. In the present study, the flow fields have been computed at blockage ratio, β of 0.5 and at Reynolds number, Re of 200 and 300. Two-dimensional simulations investigated on the effects of Reynolds number based on the vortex formation and shedding frequency. It was observed that the presence of two distinct shedding frequencies appear at higher Reynolds number due to the confinement effects where there is strong interactions between boundary layer, shear layer and the wake of the cylinder. The range of simulations conducted here has shown to produce results consistent with that available in the open literature. Therefore, OpenFOAM is found to be able to accurately capture the complex physics of the flow.

Download Full-text

VORTEX FORMATION IN PLUNGING BREAKER

Coastal Engineering Proceedings ◽

10.9753/icce.v20.54 ◽

1986 ◽

Vol 1 (20) ◽

pp. 54 ◽

Cited By ~ 4

Author(s):

T. Sakai ◽

T. Mizutani ◽

H. Tanaka ◽

Y. Tada

Keyword(s):

Flow Visualization ◽

Particle Velocity ◽

Vortex Formation ◽

Water Particle ◽

Mac Method ◽

Long Wave ◽

Wave Celerity ◽

Maximum Water ◽

Slope Beach ◽

Plunging Breaker

By a flow visualization of a plunging breaker on 1/20 slope beach in a wave tank, an existence of 2nd and 3rd horizontal vortices(Miller, 1976) and slanting vortex (Nadaoka et al., 1986) is confirmed. A MAC method is applied to simulate a violent motion after an impinging of a jet from a crest of a plunging breaker on the trough surface. The calculated maximum water particle velocity in the jet is found to reach three times the linear long wave celerity. Values of circulation of the first four horizontal vortices are calculated and their changes in time are discussed.

Download Full-text

Three-dimensional vortex formation from an oscillating, non-uniform cylinder

Journal of Fluid Mechanics ◽

10.1017/s0022112092001629 ◽

1992 ◽

Vol 238 ◽

pp. 31-54 ◽

Cited By ~ 9

Author(s):

F. Nuzzi ◽

C. Magness ◽

D. Rockwell

Keyword(s):

Flow Structure ◽

Phase Plane ◽

Shear Flows ◽

Vortex Formation ◽

Excitation Frequency ◽

Three Dimensional ◽

Two Dimensional ◽

Near Wake ◽

Shedding Frequency

A cylinder having mild variations in diameter along its span is subjected to controlled excitation at frequencies above and below the inherent shedding frequency from the corresponding two-dimensional cylinder. The response of the near wake is characterized in terms of timeline visualization and velocity traces, spectra, and phase plane representations. It is possible to generate several types of vortex formation, depending upon the excitation frequency. Globally locked-in, three-dimensional vortex formation can occur along the entire span of the flow. Regions of locally locked-in and period-doubled vortex formation can exist along different portions of the span provided the excitation frequency is properly tuned. Unlike the classical subharmonic instability in free shear flows, the occurrence of period-doubled vortex formation does not involve vortex coalescence; instead, the flow structure alternates between two different states.

Download Full-text

Flow Around Baffles

Journal of Heat Transfer ◽

10.1115/1.3246747 ◽

1984 ◽

Vol 106 (4) ◽

pp. 743-749 ◽

Cited By ~ 89

Author(s):

C. Berner ◽

F. Durst ◽

D. M. McEligot

Keyword(s):

Flow Visualization ◽

Water Flow ◽

Heat Exchangers ◽

Pressure Loss ◽

Laser Doppler Anemometry ◽

Reynolds Numbers ◽

Two Dimensional ◽

Streamwise Direction ◽

Loss Coefficients ◽

Shell And Tube

Flow visualization, manometry, and laser-Doppler anemometry have been applied to approximately two-dimensional water flow around segmental baffles with baffle spacing/depth equal to 0.4, window cuts from 10 to 50 percent, and Reynolds numbers ranging from 600–10,500 in order to simulate important aspects relating to shellside flow in shell-and-tube heat exchangers. The main features of the flow (which is eventually periodic in the streamwise direction), development lengths, pressure loss coefficients, and mean and rms velocity distributions are presented.

Download Full-text