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Research Papers: Flows in Complex Systems

High-Resolution Numerical Simulation of Low Reynolds Number Incompressible Flow About Two Cylinders in Tandem

[+] Author and Article Information
Sintu Singha, K. P. Sinhamahapatra

Department of Aerospace Engineering, IIT Kharagpur, Kharagpur, 721302 India

J. Fluids Eng 132(1), 011101 (Dec 15, 2009) (10 pages) doi:10.1115/1.4000649 History: Received March 13, 2009; Revised November 06, 2009; Published December 15, 2009

Abstract

Low Reynolds number steady and unsteady incompressible flows over two circular cylinders in tandem are numerically simulated for a range of Reynolds numbers with varying gap size. The governing equations are solved on an unstructured collocated mesh using a second-order implicit finite volume method. The effects of the gap and Reynolds number on the vortex structure of the wake and on the fluid dynamic forces acting on the cylinders are reported and discussed. Both the parameters have significant influence on the flow field. An attempt is made to unify their influence on some global parameters.

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Figures

Figure 1

Stencil (made up of P, S, and Q or R) for quadratic interpolation at face BC

Figure 2

(a) Stencil and notations for the gradients in diffusive flux across face MN. (b) Stencil for the Laplacian interpolation for the vertex M

Figure 3

(a) Schematic diagram showing the flow configuration and computational domain. (b) Part of the computational mesh at g/D=1.5.

Figure 4

Pressure distribution on the surface of the cylinders at Re=100, g/D=1.0 during peak Cl on cylinder 2; (a) cylinder 1 and (b) cylinder 2

Figure 5

Streamlines at Re=40 for different gap sizes: (a) g/D=0.2, (b) g/D=0.7, (c) g/D=1.5, (d) g/D=3.0, and (e) g/D=4.0

Figure 6

Closer view of the streamlines at Re=40 for (a) g/D=0.2 and (b) g/D=1.5

Figure 7

(a) Variation in the separation point with normalized gap at Re=40. (b) Comparison of pressure distribution on a pair of cylinders in tandem (g/D=1.0) and on an isolated cylinder at Re=40

Figure 8

Variation in drag coefficient with normalized gap at Re=40

Figure 9

Streamlines at Re=70 for different gap sizes: (a) g/D=0.2, (b) g/D=0.7, (c) g/D=1.5, (d) g/D=3.0, and (e) g/D=4.0

Figure 10

Vorticity contours at Re=70 for different gap sizes: (a) g/D=0.2, (b) g/D=0.7, (c) g/D=1.5, (d) g/D=3.0, and (e) g/D=4.0

Figure 11

Pressure contours at Re=70, g/D=3.0

Figure 12

Time dependent lift (left column) and drag (right column) coefficients at Re=70 for different gaps: (a) g/D=3.0 and (b) g/D=4.0; (c) close view of the case g/D=4.0

Figure 13

Variation in mean drag coefficient on the cylinders with normalized gap at Re=70

Figure 14

Vorticity contours at Re=100 for different gap sizes: (a) g/D=0.2, (b) g/D=0.7, (c) g/D=1.5, and (d) g/D=3.0

Figure 15

Time dependent lift (left column) and drag (right column) coefficients at Re=100: (a) g/D=0.2, (b) g/D=0.7, (c) g/D=1.5, and (d) g/D=3.0

Figure 16

Vorticity contours at Re=150; (a) g/D=3.0 and (b) g/D=4.0

Figure 17

Variation in flow parameters with nondimensional gap: (a) root mean squared lift coefficient; (b) mean drag coefficient; the dotted and solid lines represent downstream and upstream cylinders, respectively; and (c) Strouhal number for downstream cylinder. The symbols “◻,” “○,” and “△” denotes Re=100, 120, and 150, respectively.

Figure 18

Strouhal number versus Re1/2(g/D)4/5 plot

Figure 19

Mean drag coefficient of the cylinders versus Re2/3(g/D)3/2 plot

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