矩形柱周りの流れの三次元数値シミュレーション(流体工学, 流体機械)

概要

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The appcarance of a temporal irrcgularity of acrodynamic force of a rectangular cylinder with the critical depth (D/H=0.6), seems to be such startling phenomenon that is well worth investigating further. In this paper, turbulent flow around a stationary rectangular cylinder with the side ratio D/H of 0.2 to 1.0, has been computed by the LES method at high Reynolds number of 2.2×10^4. The Smagorinsky model was used as a subgrid scale (SGS) model. The main objcctives of this work are to predict and evaluate characteristics of flows for a stationary cylinder. The computational results of force coefficients such as mean and fluctuating values of drag and lift forces, Strouhal number and flow-configurations correspond well with experimental data. We confirm that the abrupt changes of the aerodynamics forces appear irregularly with the time for the cylinder with a critical section. The temporal variation of a drag force between low and high values is certified to be accompanied with the corresponding change of instantenious frequency of lift force, by using of a wavelet transform method and an analysis of frequency histogram. The time history of drag force C_D agrees well with variation of the intensity of the wavelet transform coefficients or Strauhal number from the wavelet analysis results of lift force C_L.
一般社団法人日本機械学会の論文
2002-06-25