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首页> 外文期刊>International Journal of Multiphase Flow >Modeling droplet dispersion and interphase turbulent kinetic energy transfer using a new dual-timescale Langevin model
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Modeling droplet dispersion and interphase turbulent kinetic energy transfer using a new dual-timescale Langevin model

机译：使用新的双时标Langevin模型对液滴弥散和相间湍动能传递进行建模

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Dispersion of spray droplets and the modulation of turbulence in the ambient gas by the dispersing droplets are two coupled phenomena that are closely linked to the evolution of global spray characteristics, such as the spreading rate of the spray and the spray cone angle. Direct numerical simulations (DNS) of turbulent gas flows laden with sub-Kolmogorov size particles, in the absence of gravity, report that dispersion statistics and turbulent kinetic energy (TKE) evolve on different timescales. Furthermore, each timescale behaves differently with Stokes number, a non-dimensional flow parameter (defined in this context as the ratio of the particle response time to the Kolmogorov timescale of turbulence) that characterizes how quickly a particle responds to turbulent fluctuations in the carrier or gas phase. A new dual-timescale Langevin model (DLM) composed of two coupled Langevin equations for the fluctuating velocities, one for each phase, is proposed. This model possesses a unique feature that the implied TKE and velocity autocorrelation in each phase evolve on different timescales. Consequently, this model has the capability of simultaneously predicting the disparate Stokes number trends in the evolution of dispersion statistics, such as velocity autocorrelations, and TKE in each phase. Predictions of dispersion statistics and TKE from the new model show good agreement with published DNS of non-evaporating and evaporating droplet-laden turbulent flow. (c) 2006 Elsevier Ltd. All rights reserved.
机译：喷雾液滴的分散和通过分散液滴在环境气体中对湍流的调节是两种耦合现象，它们与整体喷雾特性的演变紧密相关，例如喷雾的扩散速率和喷雾锥角。在没有重力的情况下，充满亚Kolmogorov尺寸颗粒的湍流的直接数值模拟（DNS）报告说，弥散统计量和湍动能（TKE）在不同的时间尺度上演化。此外，每个时间尺度的行为都与斯托克斯数不同，斯托克斯数是无量纲的流动参数（在此情况下定义为粒子响应时间与湍流Kolmogorov时间尺度的比率），它表征了粒子对载体或容器中湍流波动的响应速度有多快气相。提出了一种新的双时标Langevin模型（DLM），该模型由两个耦合的Langevin方程组成，用于波动速度，每一相一个。该模型具有一个独特的特征，即每个阶段的隐含TKE和速度自相关在不同的时间尺度上演化。因此，该模型具有同时预测离散统计量（例如速度自相关和每个阶段中的TKE）的离散Stokes数趋势的能力。新模型对色散统计数据和TKE的预测表明，与已发布的DNS一致，即非蒸发和蒸发液滴的湍流。 （c）2006 Elsevier Ltd.保留所有权利。

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