Models tilted plume model

For rapidly settling particles between approximately 10 and 100 jum in radius, Stokes law often is applied to correct the predictions of Gaussian plume models for settling the plume centerline is assumed to tilt downward from the horizontal at an angle whose value is given by the arc tangent of the settling velocity divided by the wind speed. 

The classic Gaussian plume model discussed above assumes that density differences between a chemical-containing plume and the surrounding air either can be neglected or can be accounted for by a small amount of plume rise or plume tilt. This condition is sometimes referred to as passive dijfusion. When gases or vapors are significantly denser than air, however, both gravity and wind affect chemical transport. 

The FSCBG model is based on a line source that is given an initial disturbance by the aircraft. The line source develops into a spray cloud that is treated as a tilted Gaussian plume. 

---