scholarly journals NUMERICAL SIMULATION OF TURBULENT FLOW IN A RECTANGULAR CHANNEL WITH PERIODICALLY MOUNTED LONGITUDINAL VORTEX GENERATORS

2011 ◽  
Vol 2 (3) ◽  
Author(s):  
PANKAJ SAHA ◽  
GAUTAM BISWAS
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Rectangular Channel ◽  
Vortex Generators ◽  
Longitudinal Vortex

Numerical Simulation of Turbulent Flow in a Rectangular Channel With Periodically Mounted Longitudinal Vortex Generators

2010 ◽  
Author(s):  
Pankaj Saha ◽  
Gautam Biswas
Keyword(s):  
Boundary Layer ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
Stokes Equations ◽  
Rectangular Channel ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Flow Structures ◽  
Reynolds Stresses ◽  
Longitudinal Vortices

Detailed flow structures in turbulent flow through a rectangular channel containing built-in winglet type vortex generators have been analyzed by means of solutions of the full Navier-Stokes equations using a Large-Eddy Simulation (LES) technique. The Reynolds numbers of investigation is 6000. The geometry of interest consists of a rectangular channel with a built-in winglet pair on the bottom wall with common-flow-down arrangement. The winglet pair induces streamwise longitudinal vortices behind it. The vortices swirl the flow around the axis parallel to the mainstream direction and disrupt the growth of thermal boundary layer entailing enhancement of heat transfer. The influence of the longitudinal vortices persists far downstream of the location of the winglet-pair. Since the structure of the turbulence is strongly affected by the streamline curvature, the flow of interest, despite the simplicity of its geometry, turns out to be extremely complex. Therefore it calls for more accurate calculation of the turbulence quantities. In the present study, flow structures are studied by using time-averaged quantities, such as the iso-contours of velocity components, vortices and turbulent stresses. The simulation shows that the secondary flow is stronger in the regions where the longitudinal vortices are more active. The wake like structures of streamwise velocity occurs due to strong distortion of the boundary layer by vortices. The spanwise distributions of turbulent kinetic energy and Reynolds stresses show the evidence of strong secondary flow. The computational results compare well with the experimental data qualitatively.

Numerical Simulation of MHD Turbulent Flow in a Rectangular Channel with Three-Surface-Coated Multi Layers

2010 ◽  
Vol 37 (5) ◽  
pp. 447-457
Author(s):  
Mitsuhiro Aoyagi ◽  
Hidetoshi Hashizume ◽  
Kazuhisa Yuki ◽  
Satoshi Ito ◽  
Takeo Muroga
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flow ◽  
Rectangular Channel

Numerical Study of Flow and Heat Transfer in Rectangular Channel With Periodic Longitudinal Vortex Generators Under Pulsating Flow

2012 ◽  
Author(s):  
Lin Tian ◽  
Wei Bai ◽  
Shanhu Xue ◽  
Zipeng Huang ◽  
Qiuwang Wang
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Numerical Study ◽  
Rectangular Channel ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Small Scale ◽  
Inlet Velocity ◽  
Flow And Heat Transfer

The unsteady turbulent flow and heat transfer in rectangular channel with periodic longitudinal vortex generators on up and bottom walls are investigated by standardized k-ε two equation turbulent model combined with standardized wall function which has been validated by steady experimental data. Influence of varying frequency and amplitude of inlet velocity varying by sine function on heat transfer and friction factor are discussed. It is found that parameters such as Tout, Tf, Tw, Nusselt number and the friction factor f vary with time periodically, phase difference occurred compared with inlet velocity. Pulsating frequency has little impact on time averaged Nusselt number. However, when amplitude increases from 0.2us to 0.8us, the heat transfer rate is augmented by about 4%. Furthermore, a critical frequency has been captured when amplitude equals to 0.8us for the channel studied. The current study will deepen understanding of unsteady flow in plate fuel assembly, which can be used in small-scale reactors.

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