The fluid dynamic interaction between a uniform free stream flow and the rotation induced flow from a sharp edged body is numerically investigated. A two-dimensional (2D) finite volume based computation is performed in this regard to simulate the laminar fluid flow around a rotating square cylinder in an unconfined medium. Body fitted grid system along with moving boundaries is used to obtain the numerical solution of the incompressible Navier–Stokes equations. The Reynolds number based on the free stream flow is kept in the range $10≤Re≤200$ with a dimensionless rotational speed of the cylinder in the range $0≤Ω≤5$. At low $Re=10$, the flow field remains steady irrespective of the rotational speed. For $50≤Re≤200$, regular low frequency Kármán vortex shedding (VS) is observed up to a critical rate of rotation ($Ωcr$). Beyond $Ωcr$, the global flow shows steady nature, although high frequency oscillations in the aerodynamic coefficients are present. The rotating circular cylinder also shows likewise degeneration of Kármán VS at some critical rotational speed. However, significant differences can be seen at higher rotation. Such fluid dynamic transport around a spinning square in an unconfined free stream flow is reported for the first time.

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