Author(s)

Takayuki Yamagata¹, Toshiyuki Hayase^2*

¹Visualization Research Center, Niigata University, Niigata, Japan.
²Institute of Fluid Science, Tohoku University, Aoba-ku Sendai, Japan.

The purpose of this study was to clarify grid convergence property of three-dimensional measurement-integrated (3D-MI) simulation for a flow behind a square cylinder with Karman vortex street. Measurement-integrated (MI) simulation is a kind of the observer in the dynamical system theory by using CFD scheme as a mathematical model of the system. In a former study, two-dimensional MI (2D-MI) simulation with a coarse grid system showed a fairly good result in comparison with a 2D ordinary (2D-O) simulation, but the results were degraded with grid refinement. In this study, 3D-MI simulation and three-dimensional ordinary (3D-O) simulation were performed with three grid systems of different grid resolutions, and their grid convergence properties were compared. As a result, all 3D-MI simulations reproduced the vortex shedding frequency identical to that of the experiment, and the flow fields obtained were very close, within 5% difference between the results, while the results of the 3D-O simulations showed variation of the solution under convergence. It is shown that the grid convergence property of 3D-MI simulation is monotonic and better than that of 3D-O simulation, whereas those of 2D-O and 2D-MI simulations for streamwise velocity fluctuation are divergent. The solution of 3D-MI simulation with a relatively coarse grid system properly reproduces the basic three-dimensional structure of the wake flow as well as the drag and lift coefficients.

Measurement-Integrated Simulation, Grid Convergence, Square Cylinder, Flow Measurement, Numerical Simulation, Pressure Measurement, Flow Observer, Karman Vortex

Yamagata, T. and Hayase, T. (2016) Grid Convergence Property of Three-Dimensional Measurement-Integrated Simulation for Unsteady Flow behind a Square Cylinder with Karman Vortex Street. Journal of Flow Control, Measurement & Visualization, 4, 125-142. doi: 10.4236/jfcmv.2016.44012.