Square Cylinder Research Papers - Academia.edu (original) (raw)

The aim of this paper is to investigate the vortex structures as well as lift and drag coefficients in flows around a square cylinder in compare with circular cylinder using the commercial Fluent software. Furthermore, the effect of the Reynolds number on the formation of the vortex structures as well as velocity field is investigated and compared for both circular and square cylinder at different times. The results show the good agreements of the drag coefficient, lift coefficient and the Strouhal number with the previous studies. Moreover, the results show that the lift coefficient is increased strongly when the Reynolds number increases; however, the drag coefficient and the Strohoul number do not change noticeably. Furthermore, increasing the Reynolds number causes that the fluctuations in lift and drag coefficients start at an earlier time.

- by and +1
- •
- Computational Fluid Dynamics, Lift Coefficient, Drag Coefficient, Square Cylinder

Flow past a square cylinder with and without corner modifications is carried out numerically by using CFD
fluent. The wake is generated by a uniform flow of Reynolds number (Re) 150 based on the characteristic
length of the cylinder, D. 2D unsteady numerical simulation is done using FVM employing pressure based
solver and PISO scheme. A computational grid independence study has been done to obtain a grid resolution
which predicts the results without any discrepancies. The flow separation point for the square cylinder with and
without corner modifications is obtained. The pressure distribution in the near wake region and around the
square cylinder surface is also investigated for different corner geometries. The results are presented in the
form of coefficient of pressure Vs Domain length/D, Coefficient of pressure along the cylinder wall and wall
shear stress along the cylinder wall. The results indicate that the flow separation in case of square cylinder
without sharp corners is delayed. The adverse pressure gradient along the surface of the cylinder and in the
near wake region is smaller for round corners. The tangential velocity of square cylinder with sharp corners is
large when compared with modified corners.
Keywords: Square Cylinder, Corner modifications, Reynolds number, wake, grid independence, flow
separation point, Pressure distribution, Lift coefficient, Drag coefficient.

Flow past a square cylinder with and without corner modifications is carried out numerically by using CFD
fluent. The wake is generated by a uniform flow of Reynolds number (Re) 150 based on the characteristic length
of the cylinder, D. 2D unsteady numerical simulation is done using FVM employing pressure based solver and
PISO scheme. A computational grid independence study has been done to obtain a grid resolution which predicts
the results without any discrepancies. The flow separation point for the square cylinder with and without corner
modifications is obtained. The pressure distribution in the near wake region and around the square cylinder
surface is also investigated for different corner geometries. The results are presented in the form of coefficient of
pressure Vs Domain length/D, Coefficient of pressure along the cylinder wall and wall shear stress along the
cylinder wall. The results indicate that the flow separation in case of square cylinder without sharp corners is
delayed. The adverse pressure gradient along the surface of the cylinder and in the near wake region is smaller
for round corners. The tangential velocity of square cylinder with sharp corners is large when compared with
modified corners.
Keywords: Square Cylinder, Corner modifications, Reynolds number, wake, grid independence, flow separation
point, Pressure distribution, Lift coefficient, Drag coefficient.

- by IJRAME Journal and +1
- •
- Flat plate, Lift Coefficient, Drag Coefficient, Square Cylinder

The enhancement of natural convection heat transfer using nanofluids from horizontal square cylinder
placed in a square enclosure is investigated numerically. Water-based Cu is used as the working nanofluid.
The investigation covered a range of Rayleigh numbers of 104
- 106
, nanoparticles volume fraction of
(0<ϕ≤0.2), enclosure width to cylinder height ratio, W/H of 2.5. The investigation includes the solution of
the governing equations in the Vorticity-Stream function space with the aid of a body fitted coordinate
system. Algebraic grid generation is used in the initial transformations, followed by an elliptic
transformation to complete the grid generation to computational domain. The resulting discretized system
of equations is solved using an ADI method. The built code is validated and the results showed an increase
in average Nusselt number with increasing the volume fraction of the nanoparticles for the whole range of
Rayleigh number. The isotherms are nearly similar when the volume fraction of nanoparticles is increased
from 0 to 0.2 for each Rayleigh number but a change in the streamlines is observed.

The momentum and forced convection heat transfer for a laminar and steady free stream flow of nanofluids past an isolated square cylinder have been studied numerically. Different nanofluids consisting of Al2O3 and CuO with base fluids of water and a 60:40 (by mass) ethylene glycol and water mixture were selected to evaluate their superiority over conventional fluids. Recent correlations for the thermal conductivity and viscosity of nanofluids, which are functions of particle volumetric concentration as well as temperature, have been employed in this paper. The simulations have been conducted for Pe = 25, 50, 100 and 200, with nanoparticle diameters of 30 and 100 nm and particle volumetric concentrations ranging from 0% to 4%. The results of heat transfer characteristics of nanofluid flow over a square cylinder showed marked improvement comparing with the base fluids. This improvement is more evident in flows with higher Peclet numbers and higher particle volume concentration, while the particle diameter imposes an adverse effect on the heat transfer characteristics. In addition, it was shown that for any given particle diameter there is an optimum value of particle concentration that results in the highest heat transfer coefficient.

- by Ehsan Ebrahimnia-Bajestan
- •
- Nanofluid (Heat Transfer), Fluent, Square Cylinder, Unconfined Flow

- by H. Niazmand
- •
- Engineering, Heat and Mass Transfer, Mathematical Sciences, Physical sciences
- by Charlotte Hemelrijk
- •
- Engineering, Mathematics, Physics, Fluid Dynamics

Direct numerical simulation (DNS) of flow past a square cylinder at a
Reynolds number of 100 has been carried out to explore the effect of blowing in the form of jet(s) on vortex shedding. Higher order spatial as well as temporal discretization has been employed for the discretization of governing equations. The varying number of jets, jet velocity profiles and different blowing velocities are studied to investigate the characteristics of vortex shedding. The parabolic velocity profile has
been found to be more effective in suppressing the vortex shedding as compared to the uniform velocity. Complete suppression of vortex shedding along with remarkable reduction in drag coefficient has been achieved for both jet velocity profiles but at different velocities. The corresponding values for uniform and parabolic jet profiles are 0.87 and 0.6, respectively at a mass flux of 0.120. The study also reveals that there is
considerable effect of the number of jets on the vortex shedding phenomena.

- by ankit shrivastava
- •
- Vortex shedding, Square Cylinder

This paper reviews previous studies on the flow around and flow-induced noise produced by a finite wall-mounted cylinder (FWMC) of circular and square cross section. The flow around a square FWMC is somewhat understood. Conversely, the flow around a circular FWMC is not well understood, particularly because of the phenomenon of spanwise cellular shedding. The effect of the aspect ratio (the ratio of cylinder span to diameter) on the near wake structure has been most extensively studied in the literature. However, the
effect of the height of the incoming boundary layer on the near wake structure has not been comprehensively investigated and is therefore unclear, despite it being identified as a major influencing parameter on the development of the wake. Similarly, only a few studies have been conducted on the flow-induced noise of FWMCs and there is a general lack of data on the flow-induced noise characteristics and mechanisms of an FWMCs in cross flow. Nevertheless, the amalgamation of the limited data set has led to several noise
generation hypotheses: (1) lower frequency tonal noise generation is due to the development of separate structures along the span of both circular and square FWMCs and (2) that increasing the boundary layer thickness will promote tonal noise generation.

- by Francisco Vargas
- •
- Turbulence modeling, Vortex shedding, Square Cylinder