Hydrodynamics of a fish-like body undulation mechanism: Scaling laws and regimes for vortex wake modes

2021 ◽  
Vol 33 (10) ◽  
pp. 101904
Author(s):  
Siddharth Gupta ◽  
Atul Sharma ◽  
Amit Agrawal ◽  
Mark C. Thompson ◽  
Kerry Hourigan
Keyword(s):  
Scaling Laws ◽  
Vortex Wake ◽  
Wake Modes

Cylinder Wake Dynamics in the Presence of Stream-Wise Harmonic Forcing

2006 ◽  
Author(s):  
M. Rodriguez ◽  
N. W. Mureithi
Keyword(s):  
Perturbation Parameter ◽  
Wake Flow ◽  
Forced Oscillations ◽  
Vortex Wake ◽  
Cylinder Wake ◽  
Drag Forces ◽  
Wake Patterns ◽  
Spatio Temporal ◽  
Wake Modes ◽  
Lift And Drag

The vortex wake flow dynamics downstream of a cylinder undergoing streamwise harmonic (fe/fs=1) forced oscillations has been investigated numerically using a CFD code for Re=1000. The steady-state of the wake flow has been analysed considering the amplitude of oscillations as a perturbation parameter. The resulting dynamics of the fluid lift and drag forces acting on the cylinder have been linked to the different vortex wake modes observed downstream of the cylinder. Forced oscillations lead to periodic, quasi-periodic and chaotic responses depending on the amplitude of oscillation of the cylinder. Different vortex wake patterns or modes (including 2S, P+S and S modes) have also been identified and described. Symmetry related bifurcations both in the computed fluid force dynamics as well as in the vortex wake patterns were identified. The key role played by spatio-temporal symmetry in the interaction between the wake flow and the oscillating cylinder has been elucidated by a Proper Orthogonal Decomposition (POD) of the wake velocity field. Symmetric and antisymmetric spatio-temporal modes were identified and bifurcations in the wake flow were explained in terms of mode interactions in the wake.

Siphon Flows in Stratified Coronal Loops

1994 ◽  
Vol 144 ◽  
pp. 185-187
Author(s):  
S. Orlando ◽  
G. Peres ◽  
S. Serio
Keyword(s):  
Heat Flux ◽  
Scaling Laws ◽  
Flow Model ◽  
Supersonic Flows ◽  
Coronal Loops ◽  
Characteristic Parameters

AbstractWe have developed a detailed siphon flow model for coronal loops. We find scaling laws relating the characteristic parameters of the loop, explore systematically the space of solutions and show that supersonic flows are impossible for realistic values of heat flux at the base of the upflowing leg.

Equilibrium scaling laws for layered spin glasses

1993 ◽  
Vol 3 (10) ◽  
pp. 2041-2062 ◽  
Author(s):  
M. J. Thill ◽  
H. J. Hilhorst
Keyword(s):  
Spin Glasses ◽  
Scaling Laws ◽  
Layered Spin

Analysis of shear bands in slow granular flows using a frictional Cosserat model

2000 ◽  
Vol 627 ◽  
Author(s):  
Prabhu R. Nott ◽  
K. Kesava Rao ◽  
L. Srinivasa Mohan
Keyword(s):  
Scaling Laws ◽  
Shear Bands ◽  
Shear Layers ◽  
Theoretical Description ◽  
Field Variable ◽  
Cosserat Continuum ◽  
Momentum Balance ◽  
Rigid Plastic ◽  
Independent Field ◽  
Cosserat Model

ABSTRACTThe slow flow of granular materials is often marked by the existence of narrow shear layers, adjacent to large regions that suffer little or no deformation. This behaviour, in the regime where shear stress is generated primarily by the frictional interactions between grains, has so far eluded theoretical description. In this paper, we present a rigid-plastic frictional Cosserat model that captures thin shear layers by incorporating a microscopic length scale. We treat the granular medium as a Cosserat continuum, which allows the existence of localised couple stresses and, therefore, the possibility of an asymmetric stress tensor. In addition, the local rotation is an independent field variable and is not necessarily equal to the vorticity. The angular momentum balance, which is implicitly satisfied for a classical continuum, must now be solved in conjunction with the linear momentum balances. We extend the critical state model, used in soil plasticity, for a Cosserat continuum and obtain predictions for flow in plane and cylindrical Couette devices. The velocity profile predicted by our model is in qualitative agreement with available experimental data. In addition, our model can predict scaling laws for the shear layer thickness as a function of the Couette gap, which must be verified in future experiments. Most significantly, our model can determine the velocity field in viscometric flows, which classical plasticity-based model cannot.

Scaling laws of cylindrical shells under lateral pressure

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1669-1671
Author(s):  
A. Tabiei ◽  
J. Sun ◽  
G. J. Simitses
Keyword(s):  
Scaling Laws ◽  
Lateral Pressure ◽  
Cylindrical Shells
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