Aerodynamic Entrainment and Resuspension

DOE-HDBK-3010-94

3.0 Liquids; Aqueous Solutions

Figure 3-7 reproduced from that reference shows the ARF tends to decrease with viscosity.

For solutions that have a viscosity >8 cp, the ARFs are less than 7E-6 with a maximum RF

of 0.9. For the range of viscosity >8 cp (surface tension >65 dyne/cm, specific gravity

>1.2) the ARF and RF are bounded by 7E-6 and 0.8 with median values of 3E-6 and 0.8.

The average ARF and RF values were 4E-6 and 0.8. Solutions with viscosities less than

8 cp are considered bounded by the values in subsection 3.2.3.1.

3.2.4

A erod yn am ic E n train m en t an d R esus pen sion

Liquid can be made airborne by the passage of air over its surfaces through either parallel

airflow or airflow directed into the surface, i.e., via whitecaps, spume, and film breakup due

to capillary action of the liquid up the sides of its container. The latter effect may only be

important for situations where the ratio of perimeter distance is a significant fraction of the

surface area as in small pools used in experimental studies. Only a thin layer at the surface

of the liquid can be involved in droplet formation since the droplets are formed by the film

fragments that would not suspend if the film were too thick or the fragments too large. The

airborne release fraction for this type of situation has been studied theoretically and measured

under two sets of conditions. Calculations indicate that particles held to heterogeneous

surfaces by a layer of water greater than 5 molecules thick cannot be resuspended at

superficial gas velocities <5000 m/s (greater than sonic velocities) (Brockman, February

1985). Other calculations performed in the paper indicate that the aerodynamic flow profile

at the surface may not be properly estimated; particles 10-m in diameter were entrained at

the lowest superficial velocity, 1.8 m/s, although most calculations indicate that the minimum

velocities are required for particles an order of magnitude larger. Nonetheless, the

calculations indicate the force necessary to suspend shallow pools of liquid probably requires

substantial superficial velocities for suspension and that release of liquid droplets under most

ordinary conditions are very low.

3.2.4.1

S p ray R elease F rom L arge O u td oor P on d

A model, SPRAYMASS, was developed from empirical formulas representing ocean sprays

(Roblyer and Owczarski, April 1992). Correlations between wind velocity and fetch

(distance from the lee shore where turbulence begins) were developed from sea-salt aerosols

(principally during surface breakup of bubbles formed in wave action) in the open sea, finite

ponds and diffusion in atmosphere-surface boundary layers. The concentration of aerosol

above ocean waves with finite fetch as a function of windspeed has been measured and is

represented by:

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