hy·dro·dy·nam·i·cal /-ɪkəl/ 形容詞
  Hy·dro·dy·nam·ic Hy·dro·dy·nam·ic·al a.  Pertaining to, or derived from, the dynamical action of water of a liquid; of or pertaining to water power.
  Hydrodynamic friction, friction produced by the viscosity of a liquid in motion.
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