Unsteady flow past a finite square cylinder mounted on a wall at low Reynolds number

Abstract The flow past a finite length square cylinder resembles flow across a short protrusion or a pin fin in a flow device. Direct numerical simulation (DNS) past a finite length square cylinder has been performed at a Reynolds number of 250. The flow field has been explored by solving three-dimensional unsteady Navier–Stokes equations using second order spatial and temporal discretizations. Four different cylinder height-to-width or aspect ratios (2, 3, 4 and 5) have been used to quantify its effect on the flow field and integral parameters. The cylinder aspect ratio is found to have significant effect on the instantaneous as well as time-averaged flow characteristics. The evolution of various flow structures associated with finite length cylinder such as wakes, tip vortices, base vortices and horse-shoe vortices are discussed. The non-dimensional frequency or Strouhal number and drag coefficient is found to increase with increase in cylinder aspect ratio.

[1]  Yang Liu,et al.  A finite cantilevered cylinder in a cross-flow , 2005 .

[2]  H. Wang,et al.  The finite-length square cylinder near wake , 2009, Journal of Fluid Mechanics.

[3]  Cheol Woo Park,et al.  Flow structure around a finite circular cylinder embedded in various atmospheric boundary layers , 2002 .

[4]  Robert J. Martinuzzi,et al.  Alternating half-loop shedding in the turbulent wake of a finite surface-mounted square cylinder with a thin boundary layer , 2011 .

[5]  I. Orlanski.  A Simple Boundary Condition for Unbounded Hyperbolic Flows , 1976 .

[6]  Hiroshi Sakamoto,et al.  Vortex shedding from a rectangular prism and a circular cylinder placed vertically in a turbulent boundary layer , 1983, Journal of Fluid Mechanics.

[7]  C. W. Hirt,et al.  Calculating three-dimensional flows around structures and over rough terrain☆ , 1972 .

[8]  Yukisada Sunabashiri,et al.  Vortex Shedding From a Circular Cylinder of Finite Length Placed on a Ground Plane , 1992 .

[9]  Rajat Mittal,et al.  Planar Symmetry in the Unsteady Wake of a Sphere , 1999 .

[10]  Jochen Fröhlich,et al.  LES of the flow around a circular cylinder of finite height , 2004 .

[11]  Arun K. Saha,et al.  Three-dimensional numerical simulations of the transition of flow past a cube , 2004 .

[12]  R. M. C. So,et al.  Local Force Measurements on Finite-Span Cylinders in a Cross-Flow , 1987 .

[13]  F. Harlow,et al.  Numerical Calculation of Time‐Dependent Viscous Incompressible Flow of Fluid with Free Surface , 1965 .

[14]  Vincent Dousset,et al.  Formation mechanism of hairpin vortices in the wake of a truncated square cylinder in a duct , 2010, Journal of Fluid Mechanics.

[15]  G. Biswas,et al.  Three-dimensional study of flow past a square cylinder at low Reynolds numbers , 2003 .

[16]  K. Karamcheti,et al.  An experiment on the flow past a finite circular cylinder at high subcritical and supercritical Reynolds numbers , 1982, Journal of Fluid Mechanics.

[17]  G. Hoffmann,et al.  Numerical simulation of spatially-developing planar jets , 1994 .

[18]  D. .. Farivar,et al.  Turbulent uniform flow around cylinders of finite length , 1981 .

[19]  Helmut Eckelmann,et al.  Influence of end plates and free ends on the shedding frequency of circular cylinders , 1982, Journal of Fluid Mechanics.

[20]  Hiroshi Sakamoto,et al.  Fluctuating Forces on a Rectangular Prism and a Circular Cylinder Placed Vertically in a Turbulent Boundary Layer , 1984 .

[21]  R. Martinuzzi,et al.  COHERENT VORTICAL AND STRAINING STRUCTURES IN THE FINITE WALL-MOUNTED SQUARE CYLINDER WAKE , 2012, Proceeding of Seventh International Symposium on Turbulence and Shear Flow Phenomena.

[22]  H. Wang,et al.  Effect of initial conditions on interaction between a boundary layer and a wall-mounted finite-length-cylinder wake , 2006 .

[23]  Amalendu Sau,et al.  Interaction of trailing vortices in the wake of a wall-mounted rectangular cylinder. , 2003, Physical review. E, Statistical, nonlinear, and soft matter physics.

[24]  I. Mabuchi,et al.  Flow around a finite circular cylinder on a flat plate , 1984 .

[25]  A. Saha.  Effect of Transitions on Flow past a Square Cylinder at Low Reynolds Number , 2009 .

[26]  J. Gerrard,et al.  An experimental investigation of the end effects on the wake of a circular cylinder towed through water at low Reynolds numbers , 1981, Journal of Fluid Mechanics.

[27]  Sinisa Krajnovic,et al.  Flow around a tall finite cylinder explored by large eddy simulation , 2011, Journal of Fluid Mechanics.