Experimental investigation of turbulent counter-rotating Taylor–Couette flows for radius ratio <i>η</i> = 0.1

Hamede, Mohammed Hussein; Merbold, Sebastian; Egbers, Christoph

doi:10.1017/jfm.2023.392

Cited by 4 publications

(2 citation statements)

References 43 publications

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“…In recent years, numerous studies have been conducted to better understand the underlying mechanisms and characteristics of this flow regime [11,12]. This flow configuration has been extensively studied for decades and in recent times, primarily in the absence of stratification [13][14][15][16][17]. Conversely, in the presence of stratification, the flow becomes more complex with more degrees of freedom [18,19].…”

Section: Introductionmentioning

confidence: 99%

Energy Budget Characterisation of the Optimal Disturbance in Stratified Shear Flow

Godwin,

Trevelyan,

Akinaga

et al. 2024

Fluids

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Stratified Taylor–Couette flow (STCF) undergoes transient growth. Recent studies have shown that there exists transient amplification in the linear regime of counter-rotating STCF. The kinetic budget of the optimal transient perturbation is analysed numerically to simulate the interaction of the shear production (SP), buoyancy flux (BP), and other energy components that contributes to the total optimal transient kinetic energy. These contributions affect the total energy by influencing the perturbation to extract kinetic energy (KE) from the mean flow. The decay of the amplification factor resulted from the positive amplification of both BP and SP, while the growth is attributed to the negative and positive amplification of BP and SP, respectively. The optimal SP is positively amplified, implying that there is the possibility of constant linear growth. These findings agree with the linear growth rate for increasing values of Grashof number.

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Section: Introductionmentioning

confidence: 99%

Energy Budget Characterisation of the Optimal Disturbance in Stratified Shear Flow

Godwin,

Trevelyan,

Akinaga

et al. 2024

Fluids

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“…Counter rotating Taylor Couette Flow refers to the flow of a fluid confined between two coaxial and independently rotating cylinders in opposite directions. This flow configuration has been extensively studied for decades and in recent times, primarily in the absence of stratification [3][4][5][6][7]. Conversely, in the presence of stratification the flow becomes more complex with more degrees of freedom in the parametric study of the dynamic behaviour [8,9].…”

Section: Introductionmentioning

confidence: 99%

Energy Budget Characterisation of the Optimal Disturbance in Stratified Shear Flow

Godwin,

Trevelyan,

Akinaga

et al. 2023

Preprint

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Stratified Taylor Couette Flow (STCF) undergoes transient growth. Recent studies have shown that there exists transient amplification in the linear regime of counter-rotating STCF. It is reported that as Gr increases, the maximum amplification factor ($G_0$) initially decays before it eventually starts growing after reaching a certain critical value Gr$_{c}$. Assuming other parameters of the model are kept constant, the value Gr$_{c}$ changes with respect to different speed ratios of the cylinders. The observed decay/growth pattern of $G_0$ is attributed to the interplay between the induced shear and buoyancy. In this study, the mechanism that triggers this observed pattern is investigated. The kinetic budget of the optimal transient perturbation is analysed numerically to simulate the interaction of the shear production (SP), buoyancy production (BP) and other energy components that contributes to the total optimal transient kinetic energy. These contributions affect the total energy by influencing the perturbation to extract kinetic energy (KE) from the mean flow. The decay of $G_0$ resulted from the positive amplification of both BP and SP, while the growth is attributed to the negative and positive amplification of BP and SP, respectively. The optimal SP is positively amplified, implying that there is the possibility of constant linear growth. These findings agree with the linear growth rate for increasing values of Gr.

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Transition to the ultimate turbulent regime in a very wide gap Taylor-Couette flow (η = 0.1) with a stationary outer cylinder

Hamede

Merbold

Egbers

2023

EPL

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The boundary layers in turbulent Taylor-Couette flow are exposed to transitions fromlaminar to turbulent states if the flow is sufficiently sheared. The present study examines thisparticular transition from the so-called ’classical’ to ’ultimate’ regime experimentally for a verywide-gap Taylor-Couette flow with a radius ratio of η = 0.1 and shear Reynolds numbers of upto Re_s = 1.5 × 10^5. In order to determine the transition, the angular momentum transportis measured by using torque sensors at the inner wall. This is complemented by measuringthe radial and azimuthal velocities via a time-resolved Particle-Image-Velocimetry (PIV). Thetransition to the ultimate regime is found at 2.5 × 104 ≤ Re_s ≤ 3.7 × 104. The dimensionlessangular momentum flux showed an effective scaling of Nu_ω ∼ Re^0.76s for Re_s ≥ 2.5×10^4and is inagreement with the scaling laws used for the ultimate regime in narrow-gap Taylor-Couette flows.In addition, a spectral analysis was performed showing the existence of highly energetic small-scaleand large-scale patterns in the classical regime whereas only highly energetic large-scale patternswere observed in the ultimate regime.

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Experimental investigation of turbulent counter-rotating Taylor–Couette flows for radius ratio η = 0.1

Cited by 4 publications

References 43 publications

Energy Budget Characterisation of the Optimal Disturbance in Stratified Shear Flow

Energy Budget Characterisation of the Optimal Disturbance in Stratified Shear Flow

Energy Budget Characterisation of the Optimal Disturbance in Stratified Shear Flow

Transition to the ultimate turbulent regime in a very wide gap Taylor-Couette flow (η = 0.1) with a stationary outer cylinder

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