Effect of apex angle on near wake vortex dynamics of triangular cylinders at intermediate Reynolds number

2021 ◽  
Author(s):  
Namit Agrawal ◽  
Maharshi Subhash
Keyword(s):  
Reynolds Number ◽  
Vortex Dynamics ◽  
Apex Angle ◽  
Wake Vortex ◽  
Near Wake

Near wake vortex dynamics of a hovering hawkmoth

2008 ◽  
Vol 25 (1) ◽  
pp. 23-36 ◽  
Author(s):  
Hikaru Aono ◽  
Wei Shyy ◽  
Hao Liu
Keyword(s):  
Vortex Dynamics ◽  
Wake Vortex ◽  
Near Wake

An Experimental Study on Flow Past an Equilateral Triangular Prism at Intermediate Reynolds Number and the Effect of its Orientation

2013 ◽  
Author(s):  
Namit Agrawal ◽  
Sushanta Dutta ◽  
B. K. Gandhi
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Flat Plate ◽  
Shear Layers ◽  
Apex Angle ◽  
Triangular Prism ◽  
Wake Region ◽  
Near Wake ◽  
Intermediate Regime ◽  
Free Shear Layers

This paper explores the effect of two orientations (0° and 180°) on near wake region of an equilateral triangular prism at intermediate Reynolds number. The paper also investigates the effect of Reynolds number on the near wake region at intermediate regime. Two orientations are defined such that the apex of the equilateral triangle is pointing upstream and downstream respectively. The flow field behind a triangular prism is different in these two orientations. When apex angle points upstream it corresponds to a fore-body attached to a flat plate while when apex angle points downstream the flat face acts like a flat plate with an after body attached to it. This after-body penetrates the recirculation zone formed behind the flat plate. These two effects are investigated for various Reynolds numbers in intermediate regime. Factors affecting drag coefficient and Strouhal number are different in both cases. In first case the fore-body changes the flow before it gets separated in two free shear layers. In other words, the fore-body affects the free shear layers formed and hence the drag. In the second case, the two shear layers are formed first then their interaction is modified by the after-body in the near wake region behind the prism. Particle Image Velocimetry (PIV) and Hotwire anemometry is being used in present study. Detailed flow field is investigated in terms of velocity magnitude, stream traces, vorticity contours, centerline recovery, power spectra, velocity profiles, Strouhal number and drag coefficient.

Wake of a Vibrating Cylinder at Re = 105

2011 ◽  
Author(s):  
R. D. Blevins ◽  
Jean-Franc¸ois Saint-Marcoux
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Flow Visualization ◽  
Vortex Dynamics ◽  
Velocity Profiles ◽  
Near Wake ◽  
Vortex Induced Vibration ◽  
Cylinder Flow

Measurements have been made of the wake of a circular cylinder at Reynolds number of 105 for a stationary cylinder and a cylinder vibrating +/− 1.25 diameters under natural vortex induced vibration. Wake velocity profiles were taken at 2, 4, 6, 12, 24 and 50 diameters downstream. The stationary cylinder profile reproduces the well known wake deficit law. The vibrating cylinder near wake is wider, deeper and flatter than that of the stationary cylinder. Flow visualization reveals the vortex dynamics in the wake. Correlation is shown with theory.

scholarly journals Flow past a square-section cylinder with a wavy stagnation face

2001 ◽  
Vol 426 ◽  
pp. 263-295 ◽  
Author(s):  
RUPAD M. DAREKAR ◽  
SPENCER J. SHERWIN
Keyword(s):  
Reynolds Number ◽  
Cross Flow ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Physical Structure ◽  
Near Wake ◽  
Hairpin Vortices ◽  
Independent State ◽  
Flow Past ◽  
Edge Surface

Numerical investigations have been performed for the flow past square-section cylinders with a spanwise geometric deformation leading to a stagnation face with a sinusoidal waviness. The computations were performed using a spectral/hp element solver over a range of Reynolds numbers from 10 to 150.Starting from fully developed shedding past a straight cylinder at a Reynolds number of 100, a sufficiently high waviness is impulsively introduced resulting in the stabilization of the near wake to a time-independent state. It is shown that the spanwise waviness sets up a cross-flow within the growing boundary layer on the leading-edge surface thereby generating streamwise and vertical components of vorticity. These additional components of vorticity appear in regions close to the inflection points of the wavy stagnation face where the spanwise vorticity is weakened. This redistribution of vorticity leads to the breakdown of the unsteady and staggered Kármán vortex wake into a steady and symmetric near-wake structure. The steady nature of the near wake is associated with a reduction in total drag of about 16% at a Reynolds number of 100 compared with the straight, non-wavy cylinder.Further increases in the amplitude of the waviness lead to the emergence of hairpin vortices from the near-wake region. This wake topology has similarities to the wake of a sphere at low Reynolds numbers. The physical structure of the wake due to the variation of the amplitude of the waviness is identified with five distinct regimes. Furthermore, the introduction of a waviness at a wavelength close to the mode A wavelength and the primary wavelength of the straight square-section cylinder leads to the suppression of the Kármán street at a minimal waviness amplitude.

Sign in / Sign up

Export Citation Format

Share Document