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  • 1
    Electronic Resource
    Electronic Resource
    High resolution measurement of turbulent structure in a channel with particle image velocimetry (1991)
    Springer
    Experiments in fluids 10 (1991), S. 301-312 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract High resolution particle image velocimetry is used to measure the turbulent velocity field for fully developed flow (Re = 2,872) in an enclosed channel. Photographs of particle displacement are obtained in a plane that is parallel to the flow and perpendicular to the walls. These are analyzed to give simultaneous measurements of two components of the velocity at more than 10,000 points. Maps of velocity vectors, spanwise vorticity and Reynolds stress reveal structural aspects of the turbulence. In particular, internal shear layers are observed, in agreement with predictions of direct numerical simulation. Ensemble-averaging of a number of photographs yields statistical properties of the velocity in good agreement with laser-Doppler velocimeter measurements, and with direct numerical simulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190246
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Application of an inverse mass transfer method to the measurement of turbulent fluctuations in the velocity gradient at the wall (1991)
    Springer
    Experiments in fluids 11 (1991), S. 65-73 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The frequency response of the concentration boundarylayer is often a concern when flush mounted mass transfer probes are used to measure turbulent fluctuations in the velocity gradient at a wall. Present practice involves the use of a solution of the mass balance equation which is linear in the fluctuating quantities. An inverse mass transfer method is explored in this paper, which avoids the linearization assumption. Improved measurements of the amplitude probability distribution and of the frequency spectrum of the streamwise component of the fluctuating velocity gradient are presented. In particular, values of rms level, skewness and flatness of 0.37, 0.96, 4.2 are obtained, in good agreement with a recent study by Alfredson, Johansson, Haritonidis and Eckelmann.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198433
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The use of scalar transport probes to measure wall shear stress in a flow with imposed oscillations (1985)
    Springer
    Experiments in fluids 3 (1985), S. 129-135 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recent studies of the influence of imposed oscillations on a turbulent flow have focused on the need for accurate measurements of the phase-averaged wall shear stress. Flush mounted wall transfer probes offer the opportunity of obtaining such results. However, considerable error can arise in interpreting these measurements (in particular, the phase of the wall stress relative to the phase of the imposed oscillations) if the time response of the scalar boundary-layer over the probe is not taken into account. This paper presents a method to correct measurements for this effect and applies it to the case of an oscillating turbulent flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280449
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Velocity measurements for a turbulent nonseparated flow over solid waves (1988)
    Springer
    Experiments in fluids 6 (1988), S. 477-486 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The laser-Doppler velocimeter was used to obtain measurements of the streamwise velocity over solid sinusoidal waves of small enough amplitude that a nonseparated flow existed. The measurements provide a critical test for Reynolds stress closure models since they are particularly sensitive to happenings in the viscous wall region (y + 〈 40), for which present theories are of uncertain accuracy. The results are compared with calculations that use an eddy viscosity model that successfully describes measurements of the wall shear stress along waves of small enough amplitude that a linear response is obtained. These calculations are in approximate agreement with measurements because they exactly account for inertia and viscous effects. However, there are significant differences which point to the inadequacy of turbulence models. In particular, non-linear effects and the amplitudes of the wave-induced velocity variations are underpredicted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196509
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Origin of turbulence-producing eddies in a channel flow (1993)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 5 (1993), S. 1011-1022 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A principal theoretical problem in understanding wall turbulence is the determination of how turbulence is created and sustained, i.e., the explanation of how energy is transferred from the mean flow to the turbulence. Flow-oriented vortical eddies have been associated with large Reynolds stresses and with the production of turbulence in the viscous region close to the wall. Their creation and evolution are investigated in a high-resolution direct numerical simulation of turbulent flow in a channel. An important finding is that they regenerate themselves by a process that appears to be weakly dependent on the outer flow. This involves the enhancement of streamwise vorticity at the wall, of opposite sign, at a location where a stress-producing eddy lifts from the wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858666
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Stability of Surfaces that are Dissolving or Being Formed by Convective Diffusion (1981)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Fluid Mechanics 13 (1981), S. 231-252 
    Details
    ISSN: 0066-4189
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.fl.13.010181.001311
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Limiting Behavior of Transverse Turbulent Velocity Fluctuations Close to a Wall (1969)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 8 (1969), S. 189-192 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/i160030a002
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Reynolds number similarity of orthogonal decomposition of the outer layer of turbulent wall flow (1994)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 6 (1994), S. 2815-2819 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experimental evidence is presented to show that in the outer region of wall-bounded turbulent flow, both the eigenfunctions and the eigenvalue spectra of the one-dimensional proper orthogonal decomposition have forms that are independent of Reynolds number when scaled by the wall friction velocity and the outer length scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.868169
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  • 9
    Electronic Resource
    Electronic Resource
    Observations of the formation of streamwise vortices by rotation of arch vortices (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 12 (2000), S. 2965-2975 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Vortices, oriented in the streamwise direction, play an important role in generating Reynolds shear stresses (and turbulence) for flow over a smooth wall. Many of these have been observed to originate from tiny streamwise vortices, located in the immediate vicinity of the wall. In this paper we identify a different process that forms about 30 percent of the streamwise vortices at locations, away from the wall, in the middle of the viscous wall layer. This is accomplished by examining the changes, with time, of the turbulent field obtained from a direct numerical simulation of turbulent flow in a channel. Streamwise vortices create a shear layer by pumping low momentum fluid from the wall. One or more small spanwise vortices are formed at the top of this layer. These grow in size and rotate in the direction of flow. Previous investigators have suggested that spanwise vortices could have a direct role in the formation of streamwise vortices. This paper describes, in detail, a process by which this is accomplished. Of particular interest is the need to recognize that the shear layer is asymmetric since it is formed by a single streamwise vortex rather than a pair of counter-rotating vortices. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1311969
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  • 10
    Electronic Resource
    Electronic Resource
    Turbulent deposition and trapping of aerosols at a wall (1992)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 4 (1992), S. 825-834 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The trajectories of aerosols are computed in a high-resolution direct numerical simulation of turbulent flow in a vertical channel. The aerosol equation of motion includes only a Stokes drag force and the influence of the aerosols on the gas flow is assumed to be negligible. Since the flow is vertical, aerosols deposit as a consequence of the turbulent fluctuations and their own inertia. It is shown that the eddies which are responsible for aerosol deposition are the same eddies that control turbulence production. Typical aerosol trajectories are shown and related to eddy structure. A free-flight theory suggested by Friedlander and Johnstone [Ind. Eng. Chem. 49, 1151 (1957)] is found to be based on reasonable assumptions about typical velocities of depositing aerosols as they pass through the viscous sublayer, but the theory is shown to be deficient in other respects. The distribution of normal velocities of the aerosols that deposit is compared to the distribution of fluid particle velocities in the viscous sublayer and some support is found for the notion that the probability distribution of Eulerian velocities may be useful in predicting deposition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.858299
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    Paper (German National Licenses)
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