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arXiv 2202.03102physics.flu-dyn
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液柱Rayleigh-Plateau模态的动力稳定性

Dynamic stabilisation of Rayleigh-Plateau modes on a liquid cylinder

Sagar Patankar, Saswata Basak, Ratul Dasgupta

摘要:

我们证明了动态稳定的轴对称傅立叶模式容易受到经典的瑞利高原(RP)的不稳定性的液体圆柱受到径向振荡体力。粘度被发现在这种稳定中起着至关重要的作用。通过Floquet分析证明RP不稳定模式可以稳定使用径向强迫线性稳定性预测。我们还解决了线性化,粘性的自由表面变形的初始值问题,获得一个三维傅立叶模式的振幅方程。该方程概括了Patankar等人(2018)早期推导的控制圆柱体上法拉第波的Mathieu方程,在时间上是非局部的,代表了笛卡尔对应物的圆柱体模拟(Beyer & Friedrich 1995)。在这个方程中的记忆项的物理解释,它表明,对于高粘度的流体,其贡献可以是相当大的。该方程的数值解的预测表明RP模式稳定高达几百强迫循环,是在不可压缩的,纳维-斯托克斯方程的数值模拟非常一致。

英文摘要:

We demonstrate dynamic stabilisation of axisymmetric Fourier modes susceptible to the classical Rayleigh-Plateau (RP) instability on a liquid cylinder by subjecting it to a radial oscillatory body force. Viscosity is found to play a crucial role in this stabilisation. Linear stability predictions are obtained via Floquet analysis demonstrating that RP unstable modes can be stabilised using radial forcing. We also solve the linearised, viscous initial-value problem for free-surface deformation obtaining an equation governing the amplitude of a three-dimensional Fourier mode. This equation generalises the Mathieu equation governing Faraday waves on a cylinder derived earlier in Patankar et al. (2018), is non-local in time and represents the cylindrical analogue of its Cartesian counterpart (Beyer & Friedrich 1995). The memory term in this equation is physically interpreted and it is shown that for highly viscous fluids, its contribution can be sizeable. Predictions from the numerical solution to this equation demonstrates RP mode stabilisation upto several hundred forcing cycles and is in excellent agreement with numerical simulations of the incompressible, Navier-Stokes equations.

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