一様流中の円柱周りの減圧挙動に対する流れのはく離の影響(流体工学,流体機械)

概要

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Due to a translational motion of a dispersed body (e.g., cylinder and particle), the pressure averaged over its wall reveals lower value than in the bulk. Such a depressurization in a uniform flow around a circular cylinder is numerically investigated. In particular, the relevance of the Karman vortex street is discussed. A dimensionless number C_<TDP>, which characterizes the level of the depressurization scaled by the fluid density and the stream velocity, is determined for the Reynolds numbers Re≤160 in a two-dimensional flow regime. A strong dependence of C_<TDP> upon the hydrodynamic unsteadiness is found: i.e., in the steady state with flow separation (6<Re<47), the slope of C_<TDP> versus Re is reduced with the Reynolds number, while beyond the onset of the unsteady flow at Re≈47, the depressurization is enhanced due to the appearance of low pressure regions forming inside the shedding vortices. Both the phase and amplitude in the temporal oscillation of C_<TDP> are well correlated with those of the drag coefficient. The correlation expressions of C_<TDP> are provided as classified according to the flow regimes.
2009-12-25