Two-dimensional fluid dynamics in a sharply bent channel: Laminar flow, separation bubble, and vortex dynamics

2016 ◽  
Vol 28 (10) ◽  
pp. 103602 ◽  
Author(s):  
Daichi Matsumoto ◽  
Koji Fukudome ◽  
Hirofumi Wada
Keyword(s):  
Fluid Dynamics ◽  
Laminar Flow ◽  
Flow Separation ◽  
Vortex Dynamics ◽  
Separation Bubble ◽  
Two Dimensional

Analogous formulation of electrodynamics and two-dimensional fluid dynamics

2014 ◽  
Vol 761 ◽  
Author(s):  
Rick Salmon
Keyword(s):  
Fluid Dynamics ◽  
Charge Density ◽  
Compressible Flow ◽  
Vortex Dynamics ◽  
Point Vortex ◽  
Point Vortices ◽  
Classical Electrodynamics ◽  
Two Dimensional ◽  
Electric Charge Density ◽  
Limiting Case

AbstractA single, simply stated approximation transforms the equations for a two-dimensional perfect fluid into a form that is closely analogous to Maxwell’s equations in classical electrodynamics. All the fluid conservation laws are retained in some form. Waves in the fluid interact only with vorticity and not with themselves. The vorticity is analogous to electric charge density, and point vortices are the analogues of point charges. The dynamics is equivalent to an action principle in which a set of fields and the locations of the point vortices are varied independently. We recover classical, incompressible, point vortex dynamics as a limiting case. Our full formulation represents the generalization of point vortex dynamics to the case of compressible flow.

Structure and dynamics of a laminar separation bubble near a wingtip

2021 ◽  
Vol 929 ◽  
Author(s):  
Connor E. Toppings ◽  
Serhiy Yarusevych
Keyword(s):  
Vortex Shedding ◽  
Vortex Dynamics ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Surface Flow ◽  
Laminar Separation Bubble ◽  
Two Dimensional ◽  
Flow Topology ◽  
Laminar Separation ◽  
The Mean

The three-dimensional flow topology of a laminar separation bubble forming on the suction surface of a semispan wing with an aspect ratio of $2.5$ and NACA 0018 airfoil section is characterised experimentally using surface pressure measurements and particle image velocimetry at a chord Reynolds number of $125\ 000$ . In the inboard region of the wing, the separation bubble is essentially two-dimensional, and the transition process in the separated shear layer leads to periodic vortex shedding, which dominates the bubble dynamics, similar to two-dimensional separation bubbles. However, progressive spanwise changes in the mean structure and vortex dynamics occur near the wingtip, leading to an open separation and eventual suppression of the bubble. In the immediate proximity of the wingtip, the boundary layer remains attached, no vortex shedding occurs and the flow remains laminar, terminating separation bubble formation. Despite variations in the mean separation bubble topology and vortex dynamics along the span, the fundamental shedding characteristics remain nearly invariant across the portion of the wing where vortex shedding occurs, and the flow appears to lock onto a common instability mode across the span, leading to minimal changes in the mean bubble characteristics despite notable changes in the effective angle of attack along the span. A comparison with available surface flow visualisations from previous studies indicates that the observed changes to the mean bubble footprint along the span of the wing are similar across different geometries and flow characteristics, suggesting similarities in the three-dimensional bubble topology and dynamics on finite wings.

Vortex dynamics of veno-arterial extracorporeal circulation: A computational fluid dynamics study

2021 ◽  
Vol 33 (6) ◽  
pp. 061908
Author(s):  
Ashwin Seetharaman ◽  
Hamed Keramati ◽  
Kollengode Ramanathan ◽  
Matthew E Cove ◽  
Sangho Kim ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vortex Dynamics ◽  
Extracorporeal Circulation

Fast and facile synthesis of two-dimensional FeIII nanosheets based on fluid-shear exfoliation for highly catalytic glycolysis of poly(ethylene terephthalate)

2021 ◽  
Author(s):  
Jae-Min Jeong ◽  
Se Bin Jin ◽  
Seon Gyu Son ◽  
Hoyoung Suh ◽  
Jong-Min Moon ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Ethylene Terephthalate ◽  
Two Dimensional ◽  
Fluid Shear ◽  
Facile Synthesis ◽  
Oxidation Method ◽  
Poly Ethylene Terephthalate ◽  
Poly Ethylene

2D FeIII nanosheets are synthesized by a fluid dynamics–assisted exfoliation and oxidation method for highly-catalyzed glycolysis reaction of PET.

The Effect of Bench Arrangements on the Natural Ventilation of a Multispan Greenhouse

2013 ◽  
Author(s):  
Sunita Kruger ◽  
Leon Pretorius
Keyword(s):  
Fluid Dynamics ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Low Velocity ◽  
Lower Velocity ◽  
Cfd Models ◽  
Temperature Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Plant Level

In this paper, the influence of various bench arrangements on the microclimate inside a two-span greenhouse is numerically investigated using three-dimensional Computational Fluid Dynamics (CFD) models. Longitudinal and peninsular arrangements are investigated for both leeward and windward opened roof ventilators. The velocity and temperature distributions at plant level (1m) were of particular interest. The research in this paper is an extension of two-dimensional work conducted previously [1]. Results indicate that bench layouts inside the greenhouse have a significant effect on the microclimate at plant level. It was found that vent opening direction (leeward or windward) influences the velocity and temperature distributions at plant level noticeably. Results also indicated that in general, the leeward facing greenhouses containing either type of bench arrangement exhibit a lower velocity distribution at plant level compared to windward facing greenhouses. The latter type of greenhouses has regions with relatively high velocities at plant level which could cause some concern. The scalar plots indicate that more stagnant areas of low velocity appear for the leeward facing greenhouses. The windward facing greenhouses also display more heterogeneity at plant level as far as temperature is concerned.

Two-dimensional vortex dynamics in decoupledYBa2Cu3O7/PrBa2Cu3O7superlattices

2003 ◽  
Vol 68 (2) ◽  
Author(s):  
X. G. Qiu ◽  
G. X. Chen ◽  
B. R. Zhao ◽  
V. V. Moshchalkov ◽  
Y. Bruynseraede
Keyword(s):  
Vortex Dynamics ◽  
Two Dimensional

Bifurcation Characteristics of Flows in Rectangular Sudden Expansion Channels

2005 ◽  
Author(s):  
Francine Battaglia ◽  
George Papadopoulos
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Critical Reynolds Number ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Expansion Ratio ◽  
Sudden Expansion ◽  
Two Dimensional ◽  
Effective Expansion ◽  
Three Dimensional Simulations

The effect of three-dimensionality on low Reynolds number flows past a symmetric sudden expansion in a channel was investigated. The geometric expansion ratio of in the current study was 2:1 and the aspect ratio was 6:1. Both experimental velocity measurements and two- and three-dimensional simulations for the flow along the centerplane of the rectangular duct are presented for Reynolds numbers in the range of 150 to 600. Comparison of the two-dimensional simulations with the experiments revealed that the simulations fail to capture completely the total expansion effect on the flow, which couples both geometric and hydrodynamic effects. To properly do so requires the definition of an effective expansion ratio, which is the ratio of the downstream and upstream hydraulic diameters and is therefore a function of both the expansion and aspect ratios. When the two-dimensional geometry was consistent with the effective expansion ratio, the new results agreed well with the three-dimensional simulations and the experiments. Furthermore, in the range of Reynolds numbers investigated, the laminar flow through the expansion underwent a symmetry-breaking bifurcation. The critical Reynolds number evaluated from the experiments and the simulations was compared to other values reported in the literature. Overall, side-wall proximity was found to enhance flow stability, helping to sustain laminar flow symmetry to higher Reynolds numbers in comparison to nominally two-dimensional double-expansion geometries. Lastly, and most importantly, when the logarithm of the critical Reynolds number from all these studies was plotted against the reciprocal of the effective expansion ratio, a linear trend emerged that uniquely captured the bifurcation dynamics of all symmetric double-sided planar expansions.

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