The Earth's rotation and laminar pipe flow

Draad, A. A.; Nieuwstadt, F. T. M.

doi:10.1017/s0022112098008702

Cited by 27 publications

(20 citation statements)

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“…This is due to an increase in laminar velocity profile asymmetry, the level of distortion being higher for Ek = 1. Given the previous results of Draad & Nieuwstadt (1998) and the excellent agreement between experiment and simulation here for two different Ekman numbers, we conclude that Coriolis forces can be significant in fully developed laminar square duct flow, especially for water. As a consequence, all of the data which follows is for 50 % glycerol/water solution (Ek ≈ 7).…”

Section: Experimental Studiessupporting

confidence: 86%

“…This deviation from the analytical solution is surprising as the velocity fluctuations remain very low (about 2 %), indicating that the flow is laminar (see figure 3(b); the fluctuations, which ideally should be zero, can be attributed to the measurement noise of the LDV system). We believe this deviation of the observed U /U b from the analytical solution can be ascribed to Coriolis effects due to the Earth's rotation as has been observed previously in pipe flows by Draad & Nieuwstadt (1998). They showed that the effect of rotation on a fully developed laminar flow can be estimated using the Ekman number, a ratio of viscous to Coriolis forces:…”

Section: Experimental Studiesmentioning

confidence: 56%

“…Numerical simulation of square duct laminar flow under the influence of Coriolis force Following the approach of Draad & Nieuwstadt (1998), we carry out a numerical simulation of fully developed laminar square duct flow, including the effect of the Earth's rotation in order to confirm our hypothesis that these effects cannot be neglected. The governing Navier-Stokes equations for the flow are as follows: …”

Section: Experimental Studiesmentioning

confidence: 99%

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Experiments on low-Reynolds-number turbulent flow through a square duct

2016

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Previous experimental studies on turbulent square duct flow have focused mainly on high Reynolds numbers for which a turbulence-induced eight-vortex secondary flow pattern exists in the cross-sectional plane. More recently, direct numerical simulations (DNS) have revealed that the flow field at Reynolds numbers close to transition can be very different; the flow in this 'marginally turbulent' regime alternating between two states characterised by four vortices. In this study, we experimentally investigate the onset criteria for transition to turbulence in square ducts. In so doing, we highlight the potential importance of Coriolis effects on this process for low-Ekman-number flows. We also present experimental data on the mean flow properties and turbulence statistics in both marginally and fully turbulent flow at relatively low Reynolds numbers using laser Doppler velocimetry. Results for both flow categories show good agreement with DNS. The switching of the flow field between two flow states at marginally turbulent Reynolds numbers is confirmed by bimodal probability density functions of streamwise velocity at certain distances from the wall as well as joint probability density functions of streamwise and wall normal velocities which feature two peaks highlighting the two states.

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Section: Experimental Studiessupporting

confidence: 86%

Section: Experimental Studiesmentioning

confidence: 56%

Section: Experimental Studiesmentioning

confidence: 99%

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Experiments on low-Reynolds-number turbulent flow through a square duct

2016

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“…One example is high-precision measurements of the velocity profile of laminar flow in a long pipe [15]. It was found that the expected parabolic profile of the velocity field was skewed by the Earth's rotation.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Earth’s Coriolis force on the large-scale circulation of turbulent Rayleigh-Bénard convection

Brown

Ahlers

2006

Physics of Fluids

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We present measurements of the large-scale circulation (LSC) of turbulent Rayleigh-Bénard convection in water-filled cylindrical samples of heights equal to their diameters. The orientation of the LSC had an irregular time dependence, but revealed a net azimuthal rotation with an average period of about 3 days for Rayleigh numbers R > ∼ 10 10 . On average there was also a tendency for the LSC to be aligned with upflow to the west and downflow to the east, even after physically rotating the apparatus in the laboratory through various angles. Both of these phenomena could be explained as a result of the coupling of the Earth's Coriolis force to the LSC. The rate of azimuthal rotation could be calculated from a model of diffusive LSC orientation meandering with a potential barrier due to the Coriolis force. The model and the data revealed an additional contribution to the potential barrier that could be attributed to the cooling system of the sample top which dominated the preferred orientation of the LSC at high R. The tendency for the LSC to be in a preferred orientation due to the Coriolis force could be cancelled by a slight tilt of the apparatus relative to gravity, although this tilt affected other aspects of the LSC that the Coriolis force did not.

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“…Consequently, subsequent modelling work has focused on the wide-channel analytical model that forms the basis for the work reported here. The fuller model can be a powerful tool to understand quantitatively the deviations from infinite width flow behaviour in actual finite-width rotating spiral channels, including the well-known Coriolis secondary flows (Mori and Nakayama, 1968;Miyazaki, 1971;Draad and Nieuwstadt, 1998;Ishigaki, 1999;Lee and Baek, 2002).…”

Section: Discussionmentioning

confidence: 99%

Hydrodynamic characteristics of a rotating spiral fluid-phase contactor

MacInnes

Zambri

2015

Chemical Engineering Science

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ReuseThis article is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) licence. This licence only allows you to download this work and share it with others as long as you credit the authors, but you can't change the article in any way or use it commercially. More information and the full terms of the licence here: https://creativecommons.org/licenses/ Rotating spiral channels enable any two immiscible fluid phases to flow counter-currently in parallel layers allowing independent control of phase flow rates and layer thicknesses. This opens the possibility of application over the full range of fluid contacting operations, including distillation, absorption, extraction and multiphase reaction with separation. A device has been developed that enables wide-ranging experimental studies to support model refinement and design of first-generation applied devices. In this first work with the new device hydrodynamic characteristics are studied for gas-liquid systems as functions of phase flow rates, rotation rate and liquid viscosity. Measurement of the heavy phase layer thickness, using image analysis based on the Young-Laplace theory for interface shape, and measurement of volume flow rate of each phase and pressure and temperature in the spiral channel allows rigorous comparisons with an existing 'wide-channel' model relating flow rates and layer thicknesses to phase properties, geometry and rotation rate. The measured thickness of the heavy-phase layer is predicted well by the wide-channel model at high rotation and phase flow rates, where the deviation from a uniform layer thickness due to menisci at the channel end walls and interface tilt from gravity are small. At low rotation rates, where significant meniscus height and tilt develop, the layer thickness is over-predicted by the wide channel model. The sub 20 µm heavy-phase layer thicknesses measured suggest operation at optimum thickness is possible with the rotating spiral over a wide range of phase and solute systems.

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The Earth's rotation and laminar pipe flow

Cited by 27 publications

References 4 publications

Experiments on low-Reynolds-number turbulent flow through a square duct

Experiments on low-Reynolds-number turbulent flow through a square duct

Effect of the Earth’s Coriolis force on the large-scale circulation of turbulent Rayleigh-Bénard convection

Hydrodynamic characteristics of a rotating spiral fluid-phase contactor

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