Formation of a Jet and Its Breakup into Drops in Liquid-Liquid Systems
Formation of a Jet and Its Breakup into Drops in Liquid-Liquid Systems
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液-液系统中射流的形成及其分解成液滴
DOI：
10.11345/nctam.51.241
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
G. Tryggvason
中科院分区：
文献类型：
--
作者：
S. Homma;J. Koga;S. Matsumoto;G. Tryggvason
采用直接数值模拟方法研究了一种牛顿液体通过小孔注入另一种不混溶的牛顿液体时形成的轴对称液体射流及其破碎成液滴的过程。采用前沿跟踪/有限差分法跟踪液-液界面的非定常运动。在密度比（ρ c/ρ j= 1.25）和粘度比（μ c/μ j= 1）不变的情况下，考察了无量纲数的各种组合（Re= 80、160和320; We= 5和8; Fr= 4、8、32和∞），其中下标c和j分别表示连续相和射流。对于所有检查的情况下，液滴断裂由于毛细管波的不稳定性。通常观察到两个最不稳定的波变成一滴的双节点破碎，因为外部流体中的旋涡运动影响破碎过程，这与空气中液体射流的破碎不同。这是液滴尺寸的分布由破碎产生并且液滴的平均尺寸不同于由线性稳定性理论预测的液滴的平均尺寸的原因之一。
The formation of an axisymmetric liquid jet when one Newtonian liquid is injected through an orifice into another immiscible Newtonian liquid, and its breakup into drops, is studied using direct numerical simulations. A front tracking/finite difference method is used to track unsteady motion of the liquid-liquid interface. Various combinations of the non-dimensional numbers are examined (Re= 80, 160, and 320; We= 5 and 8; Fr= 4, 8, 32, and∞) for constant ratios of density (ρ c⁄ ρ j= 1.25) and viscosity (μ c⁄ μ j= 1), where subscrips c and j denote continuous phase and jet, respectively. For all cases examined, the droplets break off due to capillary wave instability. Double-node breakup where two most-unstable waves become one drop, is often observed, because the vortical motions in the external fluid affect the breakup process unlike the breakup of a liquid jet in air. This is one of the reasons that a distribution of drop sizes is produced by the breakup and the averaged size of droplets differs from that predicted by linear stability theory.