Investigation of liquid–liquid drop coalescence using tomographic PIV
Investigation of liquid–liquid drop coalescence using tomographic PIV
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DOI：
10.1007/s00348-009-0810-7
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发表时间：
2010-01
影响因子：
2.4
通讯作者：
C. Ortiz-Dueñas;J. Kim;E. Longmire
中科院分区：
文献类型：
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作者：
C. Ortiz-Dueñas;J. Kim;E. Longmire
高速层析PIV被用来研究放置在液体/液体界面上的液滴的聚结;研究了单个液滴和相邻液滴（并排液滴）存在下的液滴的聚结。液滴与周围流体之间的粘度比为0.14，奥内索奇数（Oh = μd/（ρdσD）1/2）为0.011，邦德数（Bo =（ρd-ρs）gD 2/σ）为3.1-7.5。不断发展的体积速度场的完整的聚结过程允许量化的速度尺度发生在不同的时间尺度。对于单个液滴和并排液滴，聚结起始于离轴膜破裂，并且膜收缩速度比液滴流体的塌陷速度大一个数量级。这之后是向外表面波的形成和传播，该向外表面波沿着具有大约2D的波长的聚结界面。对于并排液滴，由于第二液滴和相关界面变形的存在，第一液滴的塌陷是不对称的。总的来说，层析PIV提供了洞察流动物理和固有的三维聚结过程中，将无法实现与流动可视化或平面PIV只。
High-speed tomographic PIV was used to investigate the coalescence of drops placed on a liquid/liquid interface; the coalescence of a single drop and of a drop in the presence of an adjacent drop (side-by-side drops) was investigated. The viscosity ratio between the drop and surrounding fluids was 0.14, the Ohnesorge number (Oh = μd/(ρdσD)1/2) was 0.011, and Bond numbers (Bo = (ρd−ρs)gD2/σ) were 3.1–7.5. Evolving volumetric velocity fields of the full coalescence process allowed for quantification of the velocity scales occurring over different time scales. For both single and side-by-side drops, the coalescence initiates with an off-axis film rupture and film retraction speeds an order of magnitude larger than the collapse speed of the drop fluid. This is followed by the formation and propagation of an outward surface wave along the coalescing interface with wavelength of approximately 2D. For side-by-side drops, the collapse of the first drop is asymmetric due to the presence of the second drop and associated interface deformation. Overall, tomographic PIV provides insight into the flow physics and inherent three-dimensionalities in the coalescence process that would not be achievable with flow visualization or planar PIV only.