- Simulation of the unsteady flow around rectangular cylinders using the islb method

###### Options

# Simulation of the unsteady flow around rectangular cylinders using the islb method

Date Issued

01-01-2004

Author(s)

Baskar, G.

Babu Viswanathan

Indian Institute of Technology, Madras

AbstractShow more

Incompressible flow around rectangular cylinders placed in an in finite stream was simulated using the interpolation supplemented lattice Boltzmann (ISLB) method proposed by He et. al. (J. Comput. Phys., 129, 357 (1996)). The aspect ratio (length alongow direction/height) of the cylinders was varied from 1 to 3. The Reynolds number (based on the height) was varied from 70 to about 6000. The velocity data at a point downstream of the cylinder was collected at each time step. DFT (Discrete Fourier Transform) analysis of this data was then performed, which yielded the dominant frequencies of the unsteady flow field behind the cylinder. Strouhal numbers calculated using these dominant frequencies were then compared with experimental data reported by Okajima (J. Fluid Mech., 123, 397 (1982)). For square cylinders (aspect ratio = 1), the agreement between the two was found to be good for all values of Reynolds numbers except 1000. For higher Reynolds numbers the present calculations predicted more than one dominant frequency in contrast to the experimental data. For rectangular cylinders with aspect ratio 2, the present calculations were able to accurately predict the mode shift seen in the experiments albeit at a slightly higher value of Reynolds number. For aspect ratio 3, the agreement between the computed and the experimental values of the Strouhal numbers corresponding to the dominant as well as other modes was quite good. The computing times for all these cases was found to be quite reasonable even on modest computers. © 2004 by the American Institute of Aeronautics and Astronautics, Inc.