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Calculations of the velocity profiles in the vicinity of a sphere at intermediate Reynolds numbers; consequences for the micro-anemometer calibration unit

Abstract

The axi-symmetrical steady viscous flow past a sphere in a uniform flow in a cylinder of finite length is calculated with the finite element method and a penalty function approach. Our numerical results for the drag coefficient, the standing eddy length and the angle of flow separation as a function of Reynolds number agree well with literature. The velocity profiles in the vicinity of the sphere show that for distances larger than 3 × radius of the sphere and angles much larger than the angle of flow separation the influence of the sphere is less than 5%. The velocity at the position of our micro-anemometer is equal to the velocity generated by the calibration unit within 5%. From the numerical calculations the conclusion can be drawn that spherical micro-anemometers with diameters up to 20% of the diameter of the calibration unit can be calibrated.

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Pluijm, M.J.F.P., van den Kieboom, A.M. & Massen, C.H. Calculations of the velocity profiles in the vicinity of a sphere at intermediate Reynolds numbers; consequences for the micro-anemometer calibration unit. Applied Scientific Research 44, 391–399 (1987). https://doi.org/10.1007/BF00418153

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Keywords

  • Reynolds Number
  • Finite Element Method
  • Numerical Calculation
  • Velocity Profile
  • Drag Coefficient