Vortex dynamics during blade-vortex interactions

2015 ◽  
Vol 27 (5) ◽  
pp. 053104 ◽  
Author(s):  
Di Peng ◽  
James W. Gregory
Keyword(s):  
Vortex Dynamics ◽  
Vortex Interactions

LES investigation on vortex dynamics of transient sheet/cloud cavitating flow using different vortex identification methods

2020 ◽  
pp. 2150111
Author(s):  
Shuheng Qu ◽  
Jinping Li ◽  
Huaiyu Cheng ◽  
Bin Ji
Keyword(s):  
Vortex Dynamics ◽  
Cavitating Flow ◽  
Vortex Identification ◽  
Cavitation Model ◽  
Identification Methods ◽  
Vortex Interactions ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Lift And Drag ◽  
Criterion Method

The sheet/cloud cavitating flow always contains complex multiscale vortex structures generated by the cavity cloud shedding and collapsing. In this study, the transient sheet/cloud cavitating flow around a Clark-Y hydrofoil is numerically investigated using the Large Eddy Simulation (LES) method coupled with the Zwart–Gerber–Belamri (ZGB) cavitation model. The simulation accurately reproduces the unsteady cavitation evolution process, and the predicted time-averaged lift and drag coefficients, total vapor volume variation and velocity distribution agree fairly well with the experimental measurements. The cavitation vortex dynamics are studied in detail with different vortex identification methods including the vorticity method, the [Formula: see text]-criterion method, the [Formula: see text] method, the [Formula: see text] method and the Liutex method. The vortex identification ability of the different methods in the transient sheet/cloud cavitating flow is also discussed. Generally, the Liutex method combines the advantages of the other methods and can accurately identify both the vortex position and strength. Further analysis of cavitation-vortex interactions demonstrates that the cavity cloud shedding and collapsing have a pronounced influence on the vortex structure.

scholarly journals Network-theoretic approach to sparsified discrete vortex dynamics

2015 ◽  
Vol 768 ◽  
pp. 549-571 ◽  
Author(s):  
Aditya G. Nair ◽  
Kunihiko Taira
Keyword(s):  
Vortex Dynamics ◽  
Point Vortex ◽  
Spectral Graph Theory ◽  
Theoretic Approach ◽  
Dynamics Model ◽  
Discrete Vortex ◽  
Sparse Graphs ◽  
Graph Representations ◽  
Vortex Interactions ◽  
Two Dimensional Flow

We examine discrete vortex dynamics in two-dimensional flow through a network-theoretic approach. The interaction of the vortices is represented with a graph, which allows the use of network-theoretic approaches to identify key vortex-to-vortex interactions. We employ sparsification techniques on these graph representations based on spectral theory to construct sparsified models and evaluate the dynamics of vortices in the sparsified set-up. Identification of vortex structures based on graph sparsification and sparse vortex dynamics is illustrated through an example of point-vortex clusters interacting amongst themselves. We also evaluate the performance of sparsification with increasing number of point vortices. The sparsified-dynamics model developed with spectral graph theory requires a reduced number of vortex-to-vortex interactions but agrees well with the full nonlinear dynamics. Furthermore, the sparsified model derived from the sparse graphs conserves the invariants of discrete vortex dynamics. We highlight the similarities and differences between the present sparsified-dynamics model and reduced-order models.

scholarly journals Spreading of superfluid vorticity clouds in normal-fluid turbulence

2010 ◽  
Vol 668 ◽  
pp. 58-75 ◽  
Author(s):  
DEMOSTHENES KIVOTIDES
Keyword(s):  
Fractal Dimension ◽  
Vortex Dynamics ◽  
Vortex Tube ◽  
Interface Layer ◽  
Superfluid Turbulence ◽  
Normal Fluid ◽  
Fluid Turbulence ◽  
Vortex Interactions ◽  
Consistent Model ◽  
Pattern Forming

In this paper, we formulate a self-consistent model of thermal superfluid dynamics. By solving it, we analyse the problem of superfluid vorticity cloud propagation in normal-fluid turbulence. We show that superfluid cloud expansion is driven by pattern-forming superfluid vortex instabilities taking place in the interface layer between the cloud's bulk and the outer undisturbed normal-fluid turbulence. The radius of the cloud increases linearly with time. Mutual friction transfers energy from the normal-fluid turbulence to the superfluid cloud, whilst damping the smallest normal-fluid turbulence motions. This damping action is much weaker than viscous dissipation effects in a corresponding pure normal-fluid turbulence. The energy spectrum of superfluid turbulence presents the k−3 scaling that characterizes the spiral superfluid vorticity patterns of normal vortex tube–superfluid vortex interactions. The corresponding k−2 pressure spectrum signifies the singular nature of superfluid vorticity. These two scalings coincide in wavenumber space with the Kolmogorov regime in the normal-fluid turbulence. We compute a fractal dimension df ≈ 1.652 for superfluid vorticity. Due to simpler underlying superfluid vortex dynamics in relation to the strongly nonlinear classical vortex dynamics, this fractal dimension is smaller than the corresponding dimension of vortex tube centrelines in classical turbulence.

scholarly journals Vortex Dynamics Study and Flow Visualization on Aircraft Model with Different Canard Configurations

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 144
Author(s):  
Setyawan Bekti Wibowo ◽  
Budi Basuki ◽  
Sutrisno ◽  
Tri Agung Rohmat ◽  
Soeadgihardo Siswantoro ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vortex Dynamics ◽  
Lift Force ◽  
Aerodynamic Forces ◽  
Force Coefficient ◽  
Fighter Aircraft ◽  
Vortex Interactions ◽  
A Value ◽  
Computational Fluid Dynamics Cfd

Canard configuration on fighter planes is essential for regulating flow and the occurrence of vortex interactions on the main wing, one of which is to delay stall. Stall delays are useful when the aircraft is making maneuvering or short-landing. This study observed the effect of canard configuration on various fighter aircraft models. Fighter models represented the different canard configurations, such as Sukhoi SU-30 MKI, Chengdu J-10, and Eurofighter Typhoon. Water tunnels and computational fluid dynamics (CFD) have made it easier to visualize the flow and aerodynamic forces. The results showed that at a low angle of attack (AoA) < 30°, the Chengdu J-10 and Eurofighter models had the highest lift force coefficient (Cl). When at high AoA, Cl’s highest value occurred on the Sukhoi SU-30 model with a value of 1.45 at AoA 50°. Meanwhile, the highest AoA that still had a high Cl value occurred on the Sukhoi SU-30 and Chengdu J-10 aircraft models, namely at AoA 55° with Cl values more than 1.1. The canard position in the upper of the wing would increase the Cl at low AoA, while the parallel canard position could delay the stall.

Vortex Dynamics in the Turbulent Wake of a Single Step Cylinder

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
C. Morton ◽  
S. Yarusevych
Keyword(s):  
Vortex Dynamics ◽  
Turbulent Wake ◽  
Single Step ◽  
Cylinder Wake ◽  
Near Wake ◽  
Vortex Interactions ◽  
Direct Cross ◽  
Half Loop ◽  
Turbulent Vortex Shedding ◽  
Different Diameters

The turbulent wake development of a circular cylinder with a single stepwise discontinuity in diameter was investigated experimentally using flow visualization and two-component Laser Doppler Velocimetry (LDV). A single step cylinder is comprised of two cylinders of different diameters (D and d). Experiments were performed at a Reynolds number (ReD) of 1050 and a diameter ratio (D/d) of two. A combination of hydrogen bubble and laser induced fluorescence techniques allowed visualization of complex vortex dynamics in the near wake. The results show that turbulent vortex shedding from a single step cylinder occurs in three distinct cells of constant shedding frequency. The differences in frequency and strengths between vortices in the cells lead to complex vortex interactions at the cell boundaries. The results demonstrate that vortex splitting, half-loop vortex connections, and direct cross-boundary vortex connections occur near the cell boundaries. A comparative analysis of flow visualizations and velocity measurements is used to characterize the main vortex cells and the attendant vortex interactions, producing a simplified model of vortex dynamics in the step cylinder wake for ReD = 1050 and D/d = 2.

Anisotropic Vortex Dynamics Related to Screening Currents and Microwave Currents under Magnetic Fields on High Tc Superconductors

PIERS Online ◽  
2005 ◽  
Vol 1 (1) ◽  
pp. 110-114
Author(s):  
Tamio Endo ◽  
Hong Zhu ◽  
Takahisa Sakurada ◽  
Ajay K. Sarkar ◽  
Masanori Okada ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Vortex Dynamics ◽  
High Tc Superconductors ◽  
High Tc
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