scholarly journals Asymmetric travelling waves in a square duct

2012 ◽  
Vol 693 ◽  
pp. 57-68 ◽  
Author(s):  
Shinya Okino ◽  
Masato Nagata
Keyword(s):  
Cross Sections ◽  
Mirror Symmetry ◽  
Symmetric Solution ◽  
Travelling Waves ◽  
Edge State ◽  
Duct Flow ◽  
Streamwise Vortices ◽  
Square Duct ◽  
Geometrical Difference ◽  
Asymmetric Solution

AbstractTwo types of asymmetric solutions are found numerically in square-duct flow. They emerge through a symmetry-breaking bifurcation from the mirror-symmetric solutions discovered by Okino et al. (J. Fluid Mech., vol. 657, 2010, pp. 413–429). One of them is characterized by a pair of streamwise vortices and a low-speed streak localized near one of the sidewalls and retains the shift-and-reflect symmetry. The bifurcation nature as well as the flow structure of the solution show striking resemblance to those of the asymmetric solution in pipe flow found by Pringle & Kerswell (Phys. Rev. Lett., vol. 99, 2007, A074502), despite the geometrical difference between their cross-sections. The solution seems to be embedded in the edge state of square-duct flow identified by Biau & Bottaro (Phil. Trans. R. Soc. Lond. A, vol. 367, 2009, pp. 529–544). The other solution deviates slightly from the mirror-symmetric solution from which it bifurcates: the shift-and-rotate symmetry is retained but the mirror symmetry is broken.

0504 An edge state in transitional square-duct flow

2013 ◽  
Vol 2013 (0) ◽  
pp. _0504-01_-_0504-03_
Author(s):  
Kosuke MIYAJI ◽  
Naoto ONISHI ◽  
Masaki SHIMIZU ◽  
Genta KAWAHARA
Keyword(s):  
Edge State ◽  
Duct Flow ◽  
Square Duct

scholarly journals Effects of Curvature on Unsteady Solutions through a Curved Square Duct Flow

2013 ◽  
Vol 56 ◽  
pp. 217-224 ◽  
Author(s):  
Md. Saidul Islam ◽  
Rabindra Nath Mondal
Keyword(s):  
Duct Flow ◽  
Square Duct

Laminarization of Internal Flows Under the Combined Effect of Strong Curvature and Rotation

2008 ◽  
Vol 130 (9) ◽  
Author(s):  
K. M. Guleren ◽  
I. Afgan ◽  
A. Turan
Keyword(s):  
Secondary Flows ◽  
Combined Effect ◽  
Navier Stokes ◽  
Duct Flow ◽  
Internal Flows ◽  
Square Duct ◽  
Eddy Simulation ◽  
Numerical Predictions ◽  
Wide Range ◽  
Strong Curvature

The laminarization phenomenon for the flow under the combined effect of strong curvature and rotation is discussed based on numerical predictions of large-eddy simulation (LES). Initially, the laminarization process is presented for the fully developed flow inside a spanwise rotating straight square duct. LES predictions over a wide range of rotation numbers (Ro=0–5) show that the turbulent kinetic energy decreases monotonically apart from 0.2<Ro<0.5. Subsequently, a spanwise rotating U-duct flow is considered with Ro=±0.2. The interaction of curvature and Coriolis induced secondary flows enhances the turbulence for the negative rotating case, whereas this interaction ensues strong laminarization for the positive rotating case. Finally, the laminarization is presented in the impeller of a typical centrifugal compressor, rotating at a speed of Ω=1862rpm(Ro=0.6). The resulting LES predictions are observed to be better than those of Reynolds-averaged Navier-Stokes (RANS) in the regions where turbulence is significant. However, for the regions dominated by strong laminarization, RANS results are seen to approach those of LES and experiments.

Particle Transport in a Turbulent Square Duct Flow With an Imposed Magnetic Field

2013 ◽  
Author(s):  
Rui Liu ◽  
Surya P. Vanka ◽  
Brian G. Thomas
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Continuous Flow ◽  
Duct Flow ◽  
Deposition Rates ◽  
Square Duct ◽  
Side Walls ◽  
Volume Method ◽  
The Magnetic Field ◽  
A Current

In this paper we study the particle transport and deposition in a turbulent square duct flow with an imposed magnetic field using Direct Numerical Simulations (DNS) of the continuous flow. A magnetic field induces a current and the interaction of this current with the magnetic field generates a Lorentz force which brakes the flow and modifies the flow structure. A second-order accurate finite volume method in time and space is used and implemented on a GPU. Particles are injected at the entrance to the duct continuously and their rates of deposition on the duct walls are computed for different magnetic field strengths. Because of the changes to the flow due to the magnetic field, the deposition rates are different on the top and bottom walls compared to the side walls. This is different than in a non-MHD square duct flow, where quadrant (and octant) symmetry is obtained.

A DNS Study of Aerosol Deposition in a Turbulent Square Duct Flow

2006 ◽  
Vol 40 (11) ◽  
pp. 1016-1024 ◽  
Author(s):  
Denis J. Phares ◽  
Gaurav Sharma
Keyword(s):  
Aerosol Deposition ◽  
Duct Flow ◽  
Square Duct
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