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Properties of the mean momentum balance in turbulent Taylor–Couette flow
Journal of Fluid Mechanics ( IF 3.6 ) Pub Date : 2020-03-20 , DOI: 10.1017/jfm.2020.141
Tie Wei

This paper investigates the properties of the mean momentum balance (MMB) equation in the azimuthal $\unicode[STIX]{x1D719}$ direction of a turbulent Taylor–Couette flow (TCF). The MMB- $\unicode[STIX]{x1D719}$ equation is integrated to determine the properties of the Reynolds shear stress. An approximation is developed for the Reynolds shear stress in the core region of a turbulent TCF, and the dependence of the peak Reynolds shear stress location on the Reynolds number and the gap geometry is revealed. The properties of the global integral of the turbulent Coriolis force are also revealed. For a turbulent TCF with a small gap or at high Reynolds numbers, the global integral of the turbulent Coriolis force is found to be only weakly influenced by the rotation ratio of the cylinders. Two controlling non-dimensional numbers are derived directly from the scaling analysis of the MMB- $\unicode[STIX]{x1D719}$ equation. The first is a geometry Atwood number $A_{t}\stackrel{\text{def}}{=}\unicode[STIX]{x1D6FF}/r_{ctr}$ to characterize the gap geometry, where $\unicode[STIX]{x1D6FF}$ is the gap half-width, and $r_{ctr}$ is the mid-gap radial location. The second is the friction Reynolds number $Re_{\unicode[STIX]{x1D70F},i}$ defined as $Re_{\unicode[STIX]{x1D70F},i}\stackrel{\text{def}}{=}\unicode[STIX]{x1D6FF}u_{\unicode[STIX]{x1D70F},i}/\unicode[STIX]{x1D708}$ , where $\unicode[STIX]{x1D708}$ is the kinematic viscosity and $u_{\unicode[STIX]{x1D70F},i}$ is the friction velocity at the inner cylinder. A new three-layer structure is proposed for the inner half of a turbulent TCF at sufficiently high Reynolds number, based on the force balance in the MMB- $\unicode[STIX]{x1D719}$ equation. Layer I is an inner layer, where the force balance is between the viscous force and the Reynolds shear force: $F_{visc}\approx -F_{turb}$ . Layer III occupies the core of the gap, where the force balance is between the turbulent Coriolis force and the Reynolds shear force: $F_{cori}\approx -F_{turb}$ . In Layer II, all three forces contribute to the balance. An inner scaling is developed for Layer I, and an outer scaling is developed for Layer III. The inner and outer scalings are verified against direct numerical simulation data. Similarities and differences between the turbulent TCF and a pressure-driven turbulent channel flow are elucidated.

中文翻译:

湍流 Taylor-Couette 流中平均动量平衡的性质

本文研究了湍流 Taylor-Couette 流 (TCF) 方位角 $\unicode[STIX]{x1D719}$ 方向上的平均动量平衡 (MMB) 方程的性质。MMB-$\unicode[STIX]{x1D719}$ 方程被积分以确定雷诺剪切应力的特性。开发了湍流 TCF 核心区域雷诺剪应力的近似值,并揭示了雷诺剪应力峰值位置对雷诺数和间隙几何形状的依赖性。还揭示了湍流科里奥利力的全局积分的性质。对于具有小间隙或高雷诺数的湍流 TCF,发现湍流科里奥利力的全局积分仅受圆柱旋转比的微弱影响。两个控制无量纲数直接来自 MMB-$\unicode[STIX]{x1D719}$ 方程的缩放分析。第一个是几何阿特伍德数 $A_{t}\stackrel{\text{def}}{=}\unicode[STIX]{x1D6FF}/r_{ctr}$ 来表征间隙几何,其中 $\unicode[STIX ]{x1D6FF}$ 是间隙半宽,$r_{ctr}$ 是中间间隙径向位置。第二个是摩擦雷诺数 $Re_{\unicode[STIX]{x1D70F},i}$ 定义为 $Re_{\unicode[STIX]{x1D70F},i}\s​​tackrel{\text{def}}{=} \unicode[STIX]{x1D6FF}u_{\unicode[STIX]{x1D70F},i}/\unicode[STIX]{x1D708}$ ,其中 $\unicode[STIX]{x1D708}$ 是运动粘度,$u_ {\unicode[STIX]{x1D70F},i}$ 是内圆柱的摩擦速度。提出了一种新的三层结构,用于雷诺数足够高的湍流 TCF 的内半部分,基于 MMB-$\unicode[STIX]{x1D719}$ 方程中的力平衡。第 I 层是内层,其中的力平衡在粘性力和雷诺剪切力之间: $F_{visc}\approx -F_{turb}$ 。第三层占据了间隙的核心,其中的力平衡在湍流科里奥利力和雷诺剪切力之间: $F_{cori}\approx -F_{turb}$ 。在第二层中,所有三种力都有助于平衡。为第 I 层开发了内部缩放,为第 III 层开发了外部缩放。内部和外部比例是根据直接数值模拟数据进行验证的。阐明了湍流 TCF 和压力驱动的湍流通道流之间的异同。其中力平衡在粘性力和雷诺剪切力之间: $F_{visc}\approx -F_{turb}$ 。第三层占据了间隙的核心,其中的力平衡在湍流科里奥利力和雷诺剪切力之间: $F_{cori}\approx -F_{turb}$ 。在第二层中,所有三种力都有助于平衡。为第 I 层开发了内部缩放,为第 III 层开发了外部缩放。内部和外部比例是根据直接数值模拟数据进行验证的。阐明了湍流 TCF 和压力驱动的湍流通道流之间的异同。其中力平衡在粘性力和雷诺剪切力之间: $F_{visc}\approx -F_{turb}$ 。第三层占据了间隙的核心,其中的力平衡在湍流科里奥利力和雷诺剪切力之间: $F_{cori}\approx -F_{turb}$ 。在第二层中,所有三种力都有助于平衡。为第 I 层开发了内部缩放,为第 III 层开发了外部缩放。内部和外部比例是根据直接数值模拟数据进行验证的。阐明了湍流 TCF 和压力驱动的湍流通道流之间的异同。在第二层中,所有三种力都有助于平衡。为第 I 层开发了内部缩放,为第 III 层开发了外部缩放。根据直接数值模拟数据验证内部和外部比例。阐明了湍流 TCF 和压力驱动的湍流通道流之间的异同。在第二层中,所有三种力都有助于平衡。为第 I 层开发了内部缩放,为第 III 层开发了外部缩放。内部和外部比例是根据直接数值模拟数据进行验证的。阐明了湍流 TCF 和压力驱动的湍流通道流之间的异同。
更新日期:2020-03-20
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