ArrrtuDX E PARTICLE FALLING RATES The determination of the fallin: rates for the fallout particles wac made by initially celculating the terminal velocities for purticles at various altitudes, A celected range of purticle diameters was used in making thece celcwlations. The diameters considered were: 10, 25, 50, 78, 100, 1£0, 200, 250, 375, 5CO, 750, aud 1000 Bb, Terminal veiocities for these particles were calculated for st: rting altitudes at 5000 ft increments from 0 to 100,000 ft. From these duta the averice ratec of full of the :articles through 5000 ft increments of the atrcosphere were determined. The calculation of the terminul velocities involvei the use of known laws of settling of susremied sarticles from gases, The tyxes of flow which these perticles underge ure divided inte three regions: streamline, where viscous forces predominzte; intermediate; and turtulent, where inertia forces predominate. In simplified form, the laws covern- ing there types of flow are:3/ Streamline motion, Tn 2 Kg (PoP) a2 yo intermediate region, , Turbulent regio & n, (E.1) Po - Vm = KI (P= Poy2/3 Pp ~ ° 1 _ v 1/34. 5 (£.2) i Vm = Kp —*) (2 al/e (E.3) Vy > terminal velocity K = constant, for irreruler quertz particles: Ke = 36, Ky = 17,2 ard Kp = 50, f = density of the particle f = density of the fluid d = true diameter y = kinematic viscosity = ma Po 137