The transport of airborne dusts in the near wakes of bluff bodies

Humphries, W.; Vincent, James H.

doi:10.1016/0009-2509(78)85020-9

Cited by 20 publications

(2 citation statements)

References 6 publications

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“…Therefore it is a fair working hypothesis to assume that the transport of fluid into and out of the cavity across this boundary takes place predominantly by the random motions associated with turbulent diffusion. The same is basically true for airborne scalar entities such as solid particles, although their individual motions might differ from that of local air packets owing to their inertia (Humphries & Vincent 1978). However, in this paper we shall be concerned only with small, virtually inertialess, particles, and these will reflect the transport of the air itself.…”

Section: Physical Backgroundmentioning

confidence: 96%

Transport in the near aerodynamic wakes of flat plates

Maclennan

Vincent²

1982

J. Fluid Mech.

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An experimental investigation has been carried out into the nature of the transport of airborne material in the near aerodynamic wakes of bluff bodies with simple shapes. The main attention was focused on the essential differences existing between axi- symmetric flows (as about disks) and two-dimensional flows (as about rectangular long thin flat plates). Measurements were made for such bodies of the near-wake residence time of injected small particles, along with other and more familiar near- wake properties such as the vortex-shedding frequency and base pressure. It was concluded for disks that the transport of material into and out of the near-wake region is dominated by turbulent diffusion, and is strongly influenced by free-stream turbulence, especially for free-stream turbulence whose length scale is substantially smaller than the disk diameter. For rectangular flat plates, transport is dominated by the periodic shedding of vortices, and to only a secondary extent by turbulent motions, and is not strongly influenced by free-stream turbulence.

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Section: Physical Backgroundmentioning

confidence: 96%

Transport in the near aerodynamic wakes of flat plates

Maclennan

Vincent²

1982

J. Fluid Mech.

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“…It is in this size range that it is plausible for the entry loss to increase (and hence penetration to decrease), as we observed in the forms of the minima exhibited by our experimental data. The phenomenon we have described is somewhat similar to that identi ed originally by Humphries and Vincent (1978), and elaborated later by Sato, Vincent, and Pui (1996) in their studies of particle transport in the recirculating ows in the wakes of simple-shaped bluff bodies.…”

Section: Discussionmentioning

confidence: 72%

Experimental Study of Particle Losses Close to the Entry of Thin-Walled Sampling Probes at Varying Angles to the Wind

Sreenath¹,

Ramachandran²

2001

Aerosol Science and Technology

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This article summarizes the results of an extensive experimental study of sampling losses in thin-walled probes at various values of velocity ratio R and the probe orientation with respect to the freestream. The purpose of this study was to gain insights into the complex interaction of various parameters that in uence sampling losses and the consequent effect on the overall sampling ef ciency. A 0.635 cm diameter sharp-edged tube was mounted in a small wind tunnel where the freestream velocity could be varied over a wide range of values. Polydispersed spherical glass beads were used as the test aerosol. The number concentration and the particle size distribution were measured using the aerodynamic particle sizer (APS 3310). The sampling ef ciency was determined as a function of orientation for a range of particle sizes (or Stokes number). By using an existing model to predict the aspiration ef ciency for thin-walled probes, the sampling losses could be isolated from the sampling ef ciency. In this manner a new empirical model was developed to predict the losses as a complex function of Stokes number, sampler orientation, and velocity ratio. The losses appear to be in uenced by particle inertia, impaction, gravitational settling in the boundary layer developing inside the thin-walled probe, and vena contracta or ow recirculation loss near the entry. It was evident from the results that these losses are strongly in uenced by the Stokes number and sampler orientation. The losses also increased strongly with increasing value of velocity ratio for all orientations.

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Measurements of Velocities, Temperatures, Emissions and Particle Sizes in Model Furnaces

Taylor

Whitelaw

1999

Applied Optical Measurements

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The transport of airborne dusts in the near wakes of bluff bodies

Cited by 20 publications

References 6 publications

Transport in the near aerodynamic wakes of flat plates

Transport in the near aerodynamic wakes of flat plates

Experimental Study of Particle Losses Close to the Entry of Thin-Walled Sampling Probes at Varying Angles to the Wind

Measurements of Velocities, Temperatures, Emissions and Particle Sizes in Model Furnaces

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