采用基于Level Set方法的直接数值模拟技术对黏性液体中单个气泡的上升运动进行三维模拟.数值模拟采用拟单相流模型处理气泡内外的气液两相流动,应用Level Set方法捕捉运动气泡的变形.针对Eo数从O(0)～O(2),Mo数从O(-11)～O(2)的流动范围,重点研究了上升气泡的形状特性,并与经典的气泡形状图谱进行了比较.模拟结果表明,上升气泡的形状与无量纲参数(Eo、Mo和Re)密切相关.在高Re的扁椭球区域,数值发现了气泡形状的周期性振荡行为.
Three-dimensional direct numerical simulations of the rise motion of a single bubble in viscous liquids are carried out in this study.In the simulation,the level set method is employed to capture the bubble surface and a pseudo single fluid model is used to solve the flow fields of gas and liquid phase.The shape feature for a rising bubble are studied with emphasis over a wide flow range with Eotvos number(O(0)～O(2)) and Morton number(O(-11)～O(2)).The bubble shape and rise velocity predicted by the simulation agree well with a well-known bubble regime diagram in the literature.The simulated results demonstrate that the shape of a rising bubble can be directly concerned with three dimensionless numbers (Eo、Mo and Re).It is also found that the bubble shows a periodical-shape oscillating behavior in a high Re region of the ellipsoidal regime.
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