scholarly journals A simulation study demonstrating the importance of large-scale trailing vortices in wake steering

2018 ◽  
Vol 3 (1) ◽  
pp. 243-255 ◽  
Author(s):  
Paul Fleming ◽  
Jennifer Annoni ◽  
Matthew Churchfield ◽  
Luis A. Martinez-Tossas ◽  
Kenny Gruchalla ◽  
...  
Keyword(s):  
Power Generation ◽  
Simulation Study ◽  
Large Scale ◽  
Wind Farm ◽  
Flow Structures ◽  
New Model ◽  
Trailing Vortices ◽  
Engineering Models ◽  
Large Scale Flow

Abstract. In this paper, we investigate the role of flow structures generated in wind farm control through yaw misalignment. A pair of counter-rotating vortices is shown to be important in deforming the shape of the wake and in explaining the asymmetry of wake steering in oppositely signed yaw angles. We also demonstrate that vortices generated by an upstream turbine that is performing wake steering can deflect wakes of downstream turbines, even if they are themselves aligned. We encourage the development of improvements to control-oriented engineering models of wind farm control, to include the effects of these large-scale flow structures. Such a new model would improve the predictability of control-oriented models. Further, we demonstrate that the vortex structures created in wake steering can lead to greater impact on power generation than currently modeled in control-oriented models. We propose that wind farm controllers can be made more effective if designed to take advantage of these effects.

scholarly journals From wake steering to flow control

2017 ◽  
Author(s):  
Paul Fleming ◽  
Jennifer Annoni ◽  
Matthew Churchfield ◽  
Luis Martinez ◽  
Kenny Gruchalla ◽  
...  
Keyword(s):  
Flow Control ◽  
Large Scale ◽  
Wind Farm ◽  
Control Strategies ◽  
Wind Farms ◽  
New Physics ◽  
Flow Structures ◽  
Engineering Models ◽  
Improved Performance ◽  
Large Scale Flow

Abstract. In this paper, we investigate the role of flow structures generated in wind farm control through yaw misalignment. A pair of counter-rotating vortices are shown to be important in deforming the shape of the wake and in explaining the asymmetry of wake steering in oppositely signed yaw angles. We motivate the development of new physics for control-oriented engineering models of wind farm control, which include the effects of these large-scale flow structures. Such a new model would improve the predictability of control-oriented models. Results presented in this paper indicate that wind farm control strategies, based on new control-oriented models with new physics, that target total flow control over wake redirection may be different, and perhaps more effective, than current approaches. We propose that wind farm control and wake steering should be thought of as the generation of large-scale flow structures, which will aid in the improved performance of wind farms.

Experimental Study of Large-Scale Flow Structures in an Aneurysm

2018 ◽  
Author(s):  
Paulo Yu ◽  
Vibhav Durgesh
Keyword(s):  
Large Scale ◽  
Flow Structures ◽  
Pump System ◽  
Vortical Structures ◽  
Abnormal Growth ◽  
Image Velocimetry ◽  
Large Scale Flow ◽  
The Impact ◽  
Inflow Conditions ◽  
Aneurysm Model

An aneurysm is an abnormal growth in the wall of a weakened blood vessel, and can often be fatal upon rupture. Studies have shown that aneurysm shape and hemodynamics, in conjunction with other parameters, play an important role in growth and rupture. The objective of this study was to investigate the impact of varying inflow conditions on flow structures in an aneurysm. An idealized rigid sidewall aneurysm model was prepared and the Womersley number (α) and Reynolds number (Re) values were varied from 2 to 5 and 50 to 250, respectively. A ViVitro Labs pump system was used for inflow control and Particle Image Velocimetry was used for conducting velocity measurements. The results showed that the primary vortex path varied with an increase in α, while an increase in Re was correlated to the vortex strength and formation of secondary vortical structures. The evolution and decay of vortical structures were also observed to be dependent on α and Re.

Intraseasonal to decadal variability of Rossby wave packet properties

2021 ◽  
Author(s):  
Georgios Fragkoulidis ◽  
Volkmar Wirth
Keyword(s):  
Rossby Wave ◽  
Large Scale ◽  
Decadal Variability ◽  
Phase Speed ◽  
Diagnostic Methods ◽  
Temperature And Precipitation ◽  
Ongoing Work ◽  
Large Scale Flow

<p>The large-scale extratropical upper-tropospheric flow tends to organize itself into eastward-propagating Rossby wave packets (RWPs). Investigating the spatiotemporal evolution of RWPs and the underlying physical processes has been beneficial in showcasing the role of the upper-tropospheric flow in temperature and precipitation extremes. The use of recently developed diagnostics of local in space and time wave properties has provided further insight in this regard. Motivated by the above, these diagnostic methods are now being employed to investigate the intraseasonal to decadal variability of key RWP properties such as their amplitude, phase speed, and group velocity in reanalysis datasets. It is shown that these properties exhibit a distinct seasonal and interregional variability, while interesting patterns thereof emerge. Moreover, the interannual and long-term variability in these RWP properties is explored and significant decadal trends for specific regions and seasons are highlighted. Ongoing work aims at further utilizing the presented diagnostics and analyses toward an improved understanding of the extratropical large-scale flow variability from weather to climate time scales.</p>

Coherent large–scale flow structures in turbulent convection

2008 ◽  
pp. 606-608
Author(s):  
C. Resagk ◽  
R. du Puits ◽  
E. Lobutova ◽  
A. Maystrenko ◽  
A. Thess
Keyword(s):  
Large Scale ◽  
Turbulent Convection ◽  
Flow Structures ◽  
Large Scale Flow

scholarly journals Experimental investigation of large-scale flow structures in an aircraft cabin mock-up

2020 ◽  
Vol 184 ◽  
pp. 107224 ◽  
Author(s):  
Yongzhi Zhang ◽  
Jiayu Li ◽  
Mingxin Liu ◽  
Junjie Liu ◽  
Congcong Wang
Keyword(s):  
Experimental Investigation ◽  
Large Scale ◽  
Flow Structures ◽  
Aircraft Cabin ◽  
Large Scale Flow

scholarly journals The role of crystal fabric in flow near an ice divide

2007 ◽  
Vol 53 (181) ◽  
pp. 277-288 ◽  
Author(s):  
Erin C. Pettit ◽  
Throstur Thorsteinsson ◽  
H. Paul Jacobson ◽  
Edwin D. Waddington
Keyword(s):  
Flow Pattern ◽  
Large Scale ◽  
Cone Angle ◽  
West Antarctica ◽  
Crystal Preferred Orientation ◽  
Siple Dome ◽  
Polycrystalline Ice ◽  
Measured Profile ◽  
Large Scale Flow

AbstractPolycrystalline ice near an ice divide typically shows a crystal fabric (crystal preferred orientation) with c axes clustered vertically. We explore the effect of this fabric on the large-scale flow pattern near an ice divide. We incorporate an analytical formulation for anisotropy into a non-linear flow law within a finite-element ice-sheet flow model. With four different depth profiles of crystal fabric, we find that the effect of fabric is significant only when a profile has a minimum cone angle of less than ~25º. For a steady-state divide, the shape and size of the isochrone arch can depend as much on the crystal fabric as it does on the non-linearity of ice flow. A vertically oriented fabric tends to increase the size of the isochrone arch, never to reduce it. Also, non-random fabric has little effect on the ice-divide-flow pattern when ice is modeled as a linear (Newtonian) fluid. Finally, when we use a crystal-fabric profile that closely approximates the measured profile for Siple Dome, West Antarctica, the model predicts concentrated bed-parallel shearing 300 m above the bed.

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