不混和二相の重力分離が流体運動に与える影響 : 構造・自己励起性・非線形性

概要

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Gravitational differentiation of immiscible two phases plays a very important role in the evolution of the Earth and planets. To describe the fluid dynamical effects of relative motion between two phases, governing equations for two-phase flow composed of fine immiscible particles and ambient fluid are derived from the conservation lows of mass and momentum. By using two-dimensional non-linear full equations, we analyzed numerically temporal development of fluid motion induced by finite-amplitude disturbances in particle concentration within or at the bottom of the fluid layer. The resultant flow patterms can be classified into three types: non-circulative compensation flow, cellular convection and plume-driven flow. The flow type selection is strongly dependent on non-dimensional parameters the relative velocity between two phases and Grashof number. In case of an extremely lower relative velocity, advected particles tend to make a buoyant layer above the bottom and consequently, a plume rises from the layer through an instability similar the Rayleigh-Taylor instability. Such a plume-driven flow can be self- sustained only when inhomogenious particle concentration disturbances are provided at the bottom of the fluid layer.
1997-04-25