188.8.131.52 Procedures Used to Account for Buoyancy‑Induced Dispersion.
The method of Pasquill (1976) is used to account for the initial dispersion of plumes caused by turbulent motion of the plume and turbulent entrainment of ambient air. With this method, the effective vertical dispersion σze is calculated as follows:
where σz is the vertical dispersion due to ambient turbulence and Δh is the plume rise due to momentum and/or buoyancy. The lateral plume spread is parameterized using a similar expression:
where σy is the lateral dispersion due to ambient turbulence. It should be noted that Δh is the distance‑dependent plume rise if the receptor is located between the source and the distance to final rise, and final plume rise if the receptor is located beyond the distance to final rise. Thus, if the user elects to use final plume rise at all receptors the distance‑dependent plume rise is used in the calculation of buoyancy‑induced dispersion and the final plume rise is used in the concentration equations. It should also be noted that buoyancy‑induced dispersion is not used when the Schulman‑Scire downwash option is in effect.
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APLICACIONES castellano: DIS CUS DES RAD english: DIS CUS DES RAD
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