Direct numerical simulation of the Navier-Stokes equations has been used to investigate the Taylor-Couette flow with an imposed pulsatile axial pressure gradient resulting in a spiral Poiseuille flow modulated by an oscillating forcing. Keeping the Reynolds and Taylor numbers constant, both the amplitude and frequency of the oscillating component are varied to span a small region of the phase space. In the narrow-gap geometry considered in this study, the base flow (spiral Poiseuille flow) is in the turbulent regime whereas the oscillating component is laminar. It has been found that the effect of the oscillation is to induce a global flow laminarization provided the frequency is sufficiently small (at constant amplitude) or the amplitude is sufficiently large (at constant frequency). The coupling between steady and oscillating components has been analysed with the help of long-time and phase-averaged statistics. The reverse transition mechanism has been associated to an anisotropic modification of the Reynolds stress tensor components, which has been shown to be caused by an alteration of the pressure-strain interaction.

中文翻译：

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脉动螺旋泊肃叶流

Navier-Stokes 方程的直接数值模拟已被用于研究 Taylor-Couette 流，该流具有施加的脉动轴向压力梯度，导致由振荡强迫调制的螺旋 Poiseuille 流。保持雷诺数和泰勒数不变，振荡分量的幅度和频率都会变化以跨越相空间的一个小区域。在本研究中考虑的窄间隙几何结构中，基流（螺旋泊肃叶流）处于湍流状态，而振荡分量是层流。已经发现，只要频率足够小（在恒定幅度下）或幅度足够大（在恒定频率下），振荡的效果将引起全局流层化。借助长期和相位平均统计数据，分析了稳定分量和振荡分量之间的耦合。反向转变机制与雷诺应力张量分量的各向异性修改有关，这已被证明是由压力-应变相互作用的改变引起的。