scholarly journals Experimental and numerical investigation of the vortex formation process behind a heated cylinder

2004 ◽  
Vol 16 (8) ◽  
pp. 3103-3114 ◽  
Author(s):  
Maosheng Ren ◽  
Camilo C. M. Rindt ◽  
Anton A. van Steenhoven
Keyword(s):  
Numerical Investigation ◽  
Formation Process ◽  
Vortex Formation ◽  
Heated Cylinder

Mechanisms of Enhanced Heat Transfer for Oscillating Circular Cylinders

Volume 1 ◽  
2004 ◽  
Author(s):  
Tait Pottebaum ◽  
Mory Gharib
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Vortex Formation ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Transfer Enhancement ◽  
Heated Cylinder ◽  
Wide Range ◽  
Temperature And Velocity Fields ◽  
Oscillating Circular Cylinders

Experiments were conducted to determine the relationship between wake structure and heat transfer for an oscillating circular cylinder in cross-flow. An internally heated cylinder was suspended in a water tunnel and oscillated transverse to the freestream. The cylinder’s heat transfer coefficient was measured over a wide range of oscillation amplitudes and frequencies. By comparing these results to the known wake mode regions in the amplitude-frequency plane, relationships between wake mode and heat transfer were identified. Representative cases were investigated further by using digital particle image thermometry/velocimetry (DPIT/V) to simultaneously measure the temperature and velocity fields in the near-wake. This revealed more detail about the mechanisms of heat transfer enhancement. The dynamics of the vortex formation process, including the trajectories of the vortices during roll-up, are the primary cause of the heat transfer enhancement.

Vortex rings and plasma toroidal vortices in homogeneous unbounded media. II. The study of vortex formation process

2011 ◽  
Vol 38 (9) ◽  
pp. 275-282 ◽  
Author(s):  
U. Yusupaliev ◽  
N. P. Savenkova ◽  
Yu. V. Troshchiev ◽  
S. A. Shuteev ◽  
S. A. Skladchikov ◽  
...  
Keyword(s):  
Formation Process ◽  
Vortex Formation ◽  
Vortex Rings ◽  
Toroidal Vortices ◽  
Unbounded Media

Wake Flow Behind a Cylinder With a Detached Splitter Plate

2005 ◽  
Author(s):  
Minter Cheng
Keyword(s):  
Strouhal Number ◽  
Vortex Shedding ◽  
Formation Process ◽  
Vortex Formation ◽  
Splitter Plate ◽  
Wake Flow ◽  
Plate Length ◽  
Splitter Plates ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

Fluid flow across a bluff body can induce a series alternating vortices in the downstream flow field. The vortex flow can produce adverse effects on many engineering applications. A number of studies have shown that the wake splitter plate is one of the means to stabilize the vortex formation process. However, most of the previous studies are confined to cylinders with attached splitter plates. Very few studies investigate the effects of the spacing between the cylinder and the splitter plate on the formation of wake vortices. In the present study, the effects of the splitter plate length as well as the gap distance between the splitter plate and the cylinder on the wake flow behind a cylinder have been studied experimentally for low Reynolds number of 400. Both circular and square cylinders are studied in this research. Four splitter plates with different length, 1 ≤ L/D ≤ 4, have been used and a range of cylinder and splitter plate gap distance, 0 < G/D < 6, have been studied. By using flow visualization technique and hot-film anemometer measurement, detailed measurements of the velocity distribution, the vortex shedding frequency, the wake width, and the wake formation length are carried out in order to get a clear understanding of the flow interference behavior. The experimental results indicate that splitter plates alter the vortex formation process in the wake causing a decrease in vortex shedding frequency. The Strouhal number decreases with increasing the splitter plate length as well as the gap distance between the cylinder and the splitter plate. It is shown that a jump in Strouhal number occurs at G/D of 3 to 6. The jump is splitter plate length dependent, and generally the gap distance at which jump takes place increases as the splitter plate length increases.

scholarly journals Numerical Investigation of the Cavitation Effects on the Vortex Shedding from a Hydrofoil with Blunt Trailing Edge

Fluids ◽  
2020 ◽  
Vol 5 (4) ◽  
pp. 218
Author(s):  
Jian Chen ◽  
Linlin Geng ◽  
Xavier Escaler
Keyword(s):  
Numerical Investigation ◽  
Vortex Shedding ◽  
Reference Frames ◽  
Vortex Formation ◽  
Wake Flow ◽  
Trailing Edge ◽  
Hydraulic Machinery ◽  
Laminar To Turbulent Transition ◽  
Blunt Trailing Edge ◽  
Shedding Frequency

Vortex cavitation can appear in the wake flow of hydrofoils, inducing unwanted consequences such as vibrations or unstable behaviors in hydraulic machinery and systems. To investigate the cavitation effects on hydrofoil vortex shedding, a numerical investigation of the flow around a 2D NACA0009 with a blunt trailing edge at free caviation conditions and at two degrees of cavitation developments has been carried out by means of the Zwart cavitation model and the LES WALE turbulence model which permits predicting the laminar to turbulent transition of the boundary layers. To analyze the dynamic behavior of the vortex shedding process and the coherent structures, two identification methods based on the Eulerian and Lagrangian reference frames have been applied to the simulated unsteady flow field. It is found that the cavitation occurrence in the wake significantly changes the main vortex shedding characteristics including the morphology of the vortices, the vortex formation length, the effective height of the near wake flow and the shedding frequency. The numerical results predict that the circular shape of the vortices changes to an elliptical one and that the vortex shedding frequency is significantly increased under cavitation conditions. The main reason for the frequency increase seems to be the reduction in the transverse separation between the upper and lower rows of vortices induced by the increase in the vortex formation length.

scholarly journals Analytical and Numerical investigation of natural convection in a heated cylinder using Homotopy Perturbation Method

2014 ◽  
Vol 36 (4) ◽  
pp. 669-677 ◽  
Author(s):  
Mazaher Rahim-Esbo ◽  
Shahab BayanI ◽  
Reza Mohammadyari ◽  
Alireza Khalili Asboei ◽  
Saed Mohsenian ◽  
...  
Keyword(s):  
Natural Convection ◽  
Perturbation Method ◽  
Numerical Investigation ◽  
Homotopy Perturbation Method ◽  
Heated Cylinder ◽  
Homotopy Perturbation

Vortex formation out of two-dimensional orifices

2010 ◽  
Vol 655 ◽  
pp. 198-216 ◽  
Author(s):  
GIANNI PEDRIZZETTI
Keyword(s):  
Shear Layer ◽  
Formation Process ◽  
Vortex Formation ◽  
Formation Time ◽  
Inviscid Limit ◽  
Small Scale ◽  
Two Dimensional ◽  
Single Vortex ◽  
Vortex Model ◽  
Vortex Pairs

The understanding of the vortex formation process is currently driving a novel attempt to evaluate the performance of fluid dynamics in biological systems. The concept of formation time, developed for axially symmetric orifices, is here studied in two-dimensional flows for the generation of vortex pairs. The early stage of the formation process is studied with the single vortex model in the inviscid limit. Within this framework, the equation can be written in a universal form in terms of the formation time. The single vortex model properly represents the initial circular spiralling vortex sheet and its acceleration for self-induced motion. Then, an analysis is performed by numerical simulation of the two-dimensional Navier–Stokes equations to cope with the spatially extended vortex structure. The results do not show the pinch-off phenomenon previously reported for vortex rings. The two-dimensional vortex pair tends to a stably growing structure such that, while it translates and extends longitudinally, it remains connected to the sharp edge by a shear layer whose velocity is always about twice that of the leading vortex. At larger values of the Reynolds number the instability of the shear layer develops small-scale vortices capable of destabilizing the coherent vortex growth. The absence of a critical formation number for two-dimensional vortex pairs suggests further considerations for the development of concepts of optimal vortex formation from orifices with variable curvature or of a tapered shape.

scholarly journals A numerical investigation on the vortex formation and flow separation of the oscillatory flow in jet pumps

2015 ◽  
Vol 137 (4) ◽  
pp. 1722-1731 ◽  
Author(s):  
Joris P. Oosterhuis ◽  
Simon Bühler ◽  
Theo H. van der Meer ◽  
Douglas Wilcox
Keyword(s):  
Numerical Investigation ◽  
Flow Separation ◽  
Oscillatory Flow ◽  
Vortex Formation ◽  
Jet Pumps
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