DNS of Square-Cylinder Flow Using Hybrid Wavelet-Collocation/Volume-Penalization Method

2015 ◽  
pp. 117-123
Author(s):  
G. De Stefano ◽  
O. V. Vasilyev
Keyword(s):  
Square Cylinder ◽  
Penalization Method ◽  
Cylinder Flow ◽  
Volume Penalization Method

scholarly journals A New Approach for Error Reduction in the Volume Penalization Method

2014 ◽  
Vol 16 (5) ◽  
pp. 1181-1200 ◽  
Author(s):  
Wakana Iwakami ◽  
Yuzuru Yatagai ◽  
Nozomu Hatakeyama ◽  
Yuji Hattori
Keyword(s):  
Diffusion Equation ◽  
Stokes Equations ◽  
Error Reduction ◽  
Penalization Method ◽  
New Approach ◽  
One Dimensional ◽  
Dimensional Diffusion ◽  
Mask Function ◽  
The One ◽  
Volume Penalization Method

AbstractA new approach for reducing error of the volume penalization method is proposed. The mask function is modified by shifting the interface between solid and fluid by toward the fluid region, where v and η are the viscosity and the permeability, respectively. The shift length is derived from the analytical solution of the one-dimensional diffusion equation with a penalization term. The effect of the error reduction is verified numerically for the one-dimensional diffusion equation, Burgers’ equation, and the two-dimensional Navier-Stokes equations. The results show that the numerical error is reduced except in the vicinity of the interface showing overall second-order accuracy, while it converges to a non-zero constant value as the number of grid points increases for the original mask function. However, the new approach is effectivewhen the grid resolution is sufficiently high so that the boundary layer,whose width is proportional to , is resolved. Hence, the approach should be used when an appropriate combination of ν and η is chosen with a given numerical grid.

Square-Cylinder Flow Characteristics Modulated Using Upstream Control Rod

2012 ◽  
Vol 28 (2) ◽  
pp. 279-289 ◽  
Author(s):  
S. C. Yen ◽  
S. F. Wu
Keyword(s):  
Surface Pressure ◽  
Vortex Shedding ◽  
Flow Characteristics ◽  
Flow Patterns ◽  
Square Cylinder ◽  
Control Rod ◽  
Pressure Profiles ◽  
Spacing Ratio ◽  
Cylinder Flow ◽  
Upstream Control

AbstractThe flow patterns, vortex-shedding frequency and aerodynamic performance of the square-cylinder flow were modulated using an upstream control rod. Additionally, the flow behaviors were examined using various Reynolds numbers, rotation angles, and spacing ratios. The flow patterns were visualized using the smoke-wire scheme. The global velocity fields and streamline patterns were analyzed using the particle image velocimetry (PIV). Additionally, the flow modes were characterized based on the kinematics theory. Moreover, the vortex-shedding frequencies behind upstream control rod and the square cylinder were detected using two hot-wire anemometers. The surface pressure on square cylinder was determined using a linear pressure scanner. Then, the aerodynamic parameters were calculated using the surface-pressure profiles. Three characteristic flow modes — single, attached, and bi-vortex-street — were categorized by varying the Reynolds number and spacing ratio. In the attached mode, the position of upstream control rod determined the flow characteristics. Furthermore, in the attached mode, the mean drag force of the square cylinder is about 57% lower than of single-square cylinder.

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