Transient micromixing: Examples of laminar and chaotic stirring
Transient micromixing: Examples of laminar and chaotic stirring
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瞬时微混合：层流和混沌搅拌的示例
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发表时间：
2005
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通讯作者：
J. Gleeson
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作者：
J. Gleeson
微混合装置的效率可以通过分离流体的给定初始状态达到期望的均质化水平所花费的时间来量化。在高佩克莱特数的物理相关情况下，即使在有界域内的简单二维流中，混合时间的准确预测也是一个具有挑战性的问题。本文导出了环形微混合器中混合时间依赖性的闭式解，并通过数值模拟进行了验证。发现混合时间与作为幂律的佩克莱特数成比例，但幂律指数取决于最终状态所需的均匀性水平。最近的混沌混合模型的数值模拟揭示了流动庞加莱图的准周期岛中的涡旋搅拌效应，这强烈影响混合时间。这种搅拌效应被认为是在中间时间尺度上溶质方差呈指数下降，次于渐近长时间衰减，但是......
The efficiency of a micromixing device may be quantified by the time taken for a given initial state of separated fluids to reach a desired level of homogenization. In the physically relevant case of high Peclet number the accurate prediction of the mixing time is a challenging problem, even in simple two-dimensional flows within bounded domains. In this paper a closed-form solution for the time dependence of mixing in an annular micromixer is derived and verified by numerical simulation. The mixing time is found to scale with Peclet number as a power law, but the power-law exponent depends on the level of homogeneity desired in the final state. Numerical simulation of a recent model of chaotic mixing reveals a vortexlike stirring effect in quasiperiodic islands of the Poincare map of the flow, which strongly influences the mixing time. This stirring effect is identified with an exponential decrease in solute variance on an intermediate time scale, being subdominant to the asymptotic long-time decay, but ...