Determination of mean and dynamic skin friction, separation and transition in low-speed flow with a thin-film heated element

Bellhouse, B. J.; Schultz, D. L.

doi:10.1017/s0022112066000715

Cited by 177 publications

(72 citation statements)

References 4 publications

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“…measure skin friction has become a standard practice in turbulence research (Bellhouse and Schultz, 1966;Brown, 1967;Wallace et al, 1976;Blackwelder and Eckelmann, 1977;Sreenivasan and Antonia, 1977;Kreplin and Eckelmann, 1978). Related work has also been done using flush-mounted mass-transfer analogs of hot films Zilker and Hanratty, 1979).…”

Section: 0mentioning

confidence: 99%

Flow and skin friction over natural rough beds

Paola¹

1983

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When a boundary layer develops over a bed that is hydrodynamically rough at a length scale or scales larger than the grain size (a macrorough bed), as is usually the case where bed forms are present, it is necessary to distinguish among total boundary shear stress and its components, form drag and spatially averaged skin friction. It is known that the mean-velocity field reflects the composite boundary shear stress. Above about one roughness height above the tops of the roughness elements, the velocity does not vary horizontally. Its vertical profile is semilogarithmic and scales with the total friction velocity u*t and total roughness length zot. This region is here called the integrated logarithmic layer (ILL). Below the ILL the velocity varies horizontally in response to the irregular boundary; this region is called the surface layer.In the first of two sets of experiments reported here, skin-friction measurements were made with an array of flush-mounted hot films at four points on the stoss slope of one of a field of two-dimensional immobile current ripples. Total boundary shear stress was also measured, as were mean-velocity profiles in the ILL and the surface layer. The ILL behaves as described above. Although surface-layer velocity profiles are semilogarithmic, their semilogarithmic slope is not proportional to the local skin-friction velocity, so they do not locally obey the law of the wall. Rather, the velocity field can be decomposed into a spatially averaged rotational component and a local inviscid perturbation. The measured skin-friction field is consistent with a simple model for sediment transport over the bed forms except near reattachment, where the fluctuating skin friction is important. The data are also consistent with the drag-partition theories of Einstein and Barbarossa (1952) and Engelund (1966). Normalized skin-friction spectra do not vary with streamwise position but do vary with Reynolds number; skin-friction probability density functions show significant increases in skewness and kurtosis near reattachment but do not vary strongly with Reynolds number.In the second set of experiments the skin-friction vector field was measured around isolated hemispheres, with model sedimentary tails one and four obstacle heights long and without tails. The measured skin-friction fields are not consistent with deposition along the obstacle-flow centerline downstream of reattachment, which occurs about two obstacle heights downstream of the trailing edge of the hemisphere. This applies for local bed-load erosion and deposition and for general deflation of the bed, and is not substantially altered by the presence of either tail. Measurements were also made of skin friction, total boundary shear stress and ILL velocity profiles over h,B-rough arrays of hemispheres with and without tails four roughness heights long, at two areal densities. The skin-friction field in the denser array is significantly distorted from that around an isolated element. The measured skin friction in both arrays is signif...

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Section: 0mentioning

confidence: 99%

Flow and skin friction over natural rough beds

Paola¹

1983

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“…Within this work Colella and Keith have accurately measured the shear stress on a surface piercing plate and concluded that it is not quite Gaussian in its distribution due to a skewness of 0.67. However, the voltage measurement of a hotfilm probe is not linearly related to the shear stress, [29,28]. When using constant temperature (CT) hot film transducers, the voltage measurement is a measure of the forced convection from interaction of the flow with the surface.…”

Section: Hotfilm Measurements As a Turbulent Quantitymentioning

confidence: 99%

Looking for “laminars”: Measuring intermittency on the America’s Cup race course

Binns¹,

Albina²,

Burns³

2009

Experimental Thermal and Fluid Science

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a b s t r a c tThe determination of intermittency from experimental results has been achieved in the past by a number of approximate methods, the most prolific of which involves the use of a detector function based on the square of first and second derivatives of the flow velocity with respect to time. The disadvantages of such methods are that they rely on appropriate time domain binning of the data, they are calibration dependent, they involve error propagating numerical differentiation and 50% intermittency is incorrectly diagnosed as an extremely high level of turbulence. Where experimental records are of limited time spans, calibration is difficult, measurement errors are significant and a 50% intermittency measurement is required for design purposes, the detector method loses its utility. However, recent experimental and theoretical work by Ferchichi and Tavoularis [1] has revealed a remarkably Gaussian probability distribution for the thermal passive scalar. The degree of self-similarity (analysed through the flatness of the signal) can then be used as a measure of intermittency. Flatness analysis has been used in this study on full scale data obtained experimentally on an International America's Cup Class (IACC) yacht to overcome the problems of intermittency measurement. A generalised signal conditioning technique has been proposed.

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“…They remarked that even a change in temperature of 0.1 ºC was significant. 34 The theory they presented indicated that conventional films are primarily sensitive to the difference between the film temperature and the temperature of the surroundings. Therefore, to study the thermal sensitivity of the films they simply altered the film temperature instead of the flow temperature.…”

Section: 248mentioning

confidence: 99%

MEMS Shear Stress Sensors: Promise and Progress

Sheplak

Cattafesta

Nishida

et al. 2004

24th AIAA Aerodynamic Measurement Technology and Ground Testing Conference

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This paper reviews existing microelectromechanical systems (MEMS)-based shear stress sensors. The promise and progress of MEMS scaling advantages to improve the spatial and temporal resolution and accuracy of shear stress measurement is critically reviewed. The advantages and limitations of existing devices are discussed. Finally, unresolved technical issues are summarized for future sensor development.

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Determination of mean and dynamic skin friction, separation and transition in low-speed flow with a thin-film heated element

Cited by 177 publications

References 4 publications

Flow and skin friction over natural rough beds

Flow and skin friction over natural rough beds

Looking for “laminars”: Measuring intermittency on the America’s Cup race course

MEMS Shear Stress Sensors: Promise and Progress

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