Stationary flow driven by non-sinusoidal time-periodic pressure gradients in wavy-walled channels.
Stationary flow driven by non-sinusoidal time-periodic pressure gradients in wavy-walled channels.
复制标题
波状壁通道中非正弦时间周期压力梯度驱动的稳态流动。
DOI：
10.1016/j.apm.2023.06.013
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发表时间：
2023-10
影响因子：
5
通讯作者：
Sanchez, A. L.
中科院分区：
文献类型：
--
作者：
Alaminos-Quesada, J.;Gutierrez-Montes, C.;Coenen, W.;Sanchez, A. L.
本文将正弦变化压力梯度驱动二次流的经典问题推广到复杂波形的周期性压力梯度问题，这种周期性压力梯度存在于许多振荡的生理流动中。选取细长二维波壁槽道作为正则模型问题。根据标准的定常流动分析(适用于脉动运动的冲程长度与通道波长之比的小值)，空间周期流动用的幂函数展开来描述，并假定沃姆斯利数为阶单位。在前导阶处找到的解涉及在任何给定点具有零时间平均值的时间周期速度。在正弦压力梯度的情况下，惯性效应以以下顺序进入，以净流量为零的循环涡流的形式诱导稳定流动。通过将分析进行到以下阶数，寻求这种二次流的改进的两项渐近描述。结果表明，当压力梯度具有多个谐波的波形时，所得到的速度修正呈现非零流量，而在单频情况下不存在，这使得沿通道的定常对流传输成为可能。用直接数值模拟的方法研究了惯性的影响，并给出了渐近极限的有效范围。将数值计算得到的时间平均速度与二项渐近描述进行了比较，结果表明，对于大于0.5的值，二项渐近描述仍然非常准确。作为一个说明性的例子，模型问题的结果被用来研究由心脏和呼吸周期驱动的沿椎管的脑脊液流动，其特征是明显的非正弦波形。
The classical problem of secondary flow driven by a sinusoidally varying pressure gradient is extended here to address periodic pressure gradients of complex waveform, which are present in many oscillatory physiological flows. A slender two-dimensional wavy-walled channel is selected as a canonical model problem. Following standard steady-streaming analyses, valid for small values of the ratio of the stroke length of the pulsatile motion to the channel wavelength, the spatially periodic flow is described in terms of power-law expansions of , with the Womersley number assumed to be of order unity. The solution found at leading order involves a time-periodic velocity with a zero time-averaged value at any given point. As in the case of a sinusoidal pressure gradient, effects of inertia enter at the following order to induce a steady flow in the form of recirculating vortices with zero net flow rate. An improved two-term asymptotic description of this secondary flow is sought by carrying the analysis to the following order. It is found that, when the pressure gradient has a waveform with multiple harmonics, the resulting velocity corrections display a nonzero flow rate, not present in the single-frequency case, which enables stationary convective transport along the channel. Direct numerical simulations for values of of order unity are used to investigate effects of inertia and delineate the range of validity of the asymptotic limit . The comparisons of the time-averaged velocity obtained numerically with the two-term asymptotic description reveals that the latter remains remarkably accurate for values of exceeding 0.5. As an illustrative example, the results of the model problem are used to investigate the cerebrospinal-fluid flow driven along the spinal canal by the cardiac and respiratory cycles, characterized by markedly non-sinusoidal waveforms.
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影响因子：
7.3
作者：
Aktas, Goekmen;Kollmeier, Jost M.;Dreha-Kulaczewski, Steffi
通讯作者：
Dreha-Kulaczewski, Steffi
影响因子：
3.7
作者：
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影响因子：
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作者：
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通讯作者：
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通讯作者：
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影响因子：
3.7
作者：
Alaminos-Quesada, J.;Coenen, W.;Sanchez, A. L.
通讯作者：
Sanchez, A. L.