scholarly journals Flow states and transitions in flows past arrays of tandem cylinders

2021 ◽  
Vol 910 ◽  
Author(s):  
Negar Hosseini ◽  
Martin D. Griffith ◽  
Justin S. Leontini
Keyword(s):  
Tandem Cylinders ◽  
Flow States

Abstract

scholarly journals Interactions between Tandem Cylinders in an Open Channel: Impact on Mean and Turbulent Flow Characteristics

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1718
Author(s):  
Hasan Zobeyer ◽  
Abul B. M. Baki ◽  
Saika Nowshin Nowrin
Keyword(s):  
Turbulent Flow ◽  
Open Channel ◽  
Recirculation Zone ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Flow Recirculation ◽  
Tandem Cylinders ◽  
Flow Development ◽  
The Mean ◽  
Recirculation Length

The flow hydrodynamics around a single cylinder differ significantly from the flow fields around two cylinders in a tandem or side-by-side arrangement. In this study, the experimental results on the mean and turbulence characteristics of flow generated by a pair of cylinders placed in tandem in an open-channel flume are presented. An acoustic Doppler velocimeter (ADV) was used to measure the instantaneous three-dimensional velocity components. This study investigated the effect of cylinder spacing at 3D, 6D, and 9D (center to center) distances on the mean and turbulent flow profiles and the distribution of near-bed shear stress behind the tandem cylinders in the plane of symmetry, where D is the cylinder diameter. The results revealed that the downstream cylinder influenced the flow development between cylinders (i.e., midstream) with 3D, 6D, and 9D spacing. However, the downstream cylinder controlled the flow recirculation length midstream for the 3D distance and showed zero interruption in the 6D and 9D distances. The peak of the turbulent metrics generally occurred near the end of the recirculation zone in all scenarios.

scholarly journals Analysis of fluid flow states in viscometers in ansys software

2021 ◽  
Vol 1067 (1) ◽  
pp. 012091
Author(s):  
H N Azziz ◽  
E Q Hussein ◽  
M A Abdulhameed
Keyword(s):  
Fluid Flow ◽  
Ansys Software ◽  
Flow States

Metabolism of the fat cell in low-flow states

1966 ◽  
Vol 6 (6) ◽  
pp. 254-258 ◽  
Author(s):  
William Schumer
Keyword(s):  
Low Flow ◽  
Fat Cell ◽  
Flow States

Three-dimensional wake transition

1996 ◽  
Vol 328 ◽  
pp. 345-407 ◽  
Author(s):  
C. H. K. Williamson
Keyword(s):  
Shear Layer ◽  
Three Dimensional ◽  
Streamwise Vortex ◽  
Physical Structure ◽  
Small Scale ◽  
Half Cycle ◽  
Vortex Loops ◽  
Wake Transition ◽  
Mode A ◽  
Flow States

It is now well-known that the wake transition regime for a circular cylinder involves two modes of small-scale three-dimensional instability (modes A and B), depending on the regime of Reynolds number (Re), although almost no understanding of the physical origins of these instabilities, or indeed their effects on near-wake formation, have hitherto been made clear. We address these questions in this paper. In particular, it is found that the two different modes A and B scale on different physical features of the flow. Mode A has a larger spanwise wavelength of around 3–4 diameters, and scales on the larger physical structure in the flow, namely the primary vortex core. The wavelength for mode A is shown to be the result of an ‘elliptic instability’ in the nearwake vortex cores. The subsequent nonlinear growth of vortex loops is due to a feedback from one vortex to the next, involving spanwise-periodic deformation of core vorticity, which is then subject to streamwise stretching in the braid regios. This mode gives an out-of-phase streamwise vortex pattern.In contrast, mode-B instability has a distinctly smaller wavelength (1 diameter) which scales on the smaller physical structure in the flow, the braid shear layer. It is a manifestation of an instability in a region of hyperbolic flow. It is quite distinct from other shear flows, in that it depends on the reverse flow of the bluff-body wake; the presence of a fully formed streamwise vortex system, brought upstream from a previous half-cycle, in proximity to the newly evolving braid shear layer, leads to an in-phase stream-wise vortex array, in strong analogy with the ‘Mode 1’ of Meiburg & Lasheras (1988) for a forced unseparated wake. In mode B, we also observe amalgamation of streamwise vortices from a previous braid with like-sign vortices in the subsequent braid.It is deduced that the large scatter in previous measurements concerning mode A is due to the presence of vortex dislocations. Dislocations are triggered at the sites of some vortex loops of mode A, and represent a natural breakdown of the periodicity of mode A instability. By minimizing or avoiding the dislocations which occur from end contamination or which occur during wake transition, we find an excellent agreement of both critical Re and spanwise wavelength of mode A with the recent secondary stability analysis of Barkley & Henderson (1996).Wake transition is further characterized by velocity and pressure measurements. It is consistent that, when mode-A instability and large-scale dislocations appear, one finds a reduction of base suction, a reduction of (two-dimensional) Reynolds stress level, a growth in size of the formation region, and a corresponding drop in Strouhal frequency. Finally, the present work leads us to a new clarification of the possible flow states through transition. Right through this regime of Re, there exist two distinct and continuous Strouhal frequency curves: the upper one corresponds with purley small- scale instabilities (e.g. denoted as mode A), while the lower curve corresponds with a combination of small-scale plus dislocation structures (e.g. mode A*). However, some of the flow states are transient or ‘unstable’, and the natural transitioning wake appears to follow the scenario: (2D→A*→B).

scholarly journals The Role of Nonduality in the Relationship Between Flow States and Well-Being

Mindfulness ◽  
2021 ◽  
Author(s):  
Julianna M. Lynch ◽  
Allison S. Troy
Keyword(s):  
Positive Emotion ◽  
Satisfaction With Life ◽  
Well Being ◽  
Theoretical Work ◽  
Subjective Well Being ◽  
Psychological Well Being ◽  
The Relationship ◽  
Flow States

Abstract Objectives The current study investigated the hypothesis that the relationship between flow states and well-being is mediated by nondual experiences. Past empirical and theoretical work suggests flow states share similarities with nondual experiences. The current study expanded upon previous work by examining the relationships between flow, nondual experiences, emotion, and well-being. Methods Students enrolled in various artistic classes (N = 104) were surveyed once a week for four weeks. Participants reported on their experiences of flow, nonduality, emotion, and psychological and subjective well-being. Results Higher scores on measures of both flow (b = 7.03, SE = 0.82, p < .001) and nondual experiences (b = 0.17, SE = 0.02, p < .001) predicted increased positive emotion immediately after class. Nondual experiences partially mediated this relationship, such that when accounting for nondual experiences, the relationship between flow and positive emotion was significantly decreased (b = 4.30, SE = 0.45, p < .001). Longitudinally, nondual experience also mediated the relationship between flow and satisfaction with life (Sobel t = 1.94, SE = 1.06, p = .05). However, while flow predicted increased psychological well-being (b = 0.32, SE = 0.14, p = .02) after the four weeks, nondual experience did not (b = −0.003, SE = 0.002, p = .13). Conclusions These findings suggest that flow states may facilitate some features of nonduality and share similarities with meditative states. Additionally, the link between flow and well-being may be explained by its similarities to meditative states, and that creative activities could be useful in fostering well-being.

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