Question

5) rain drop falls because the density of liquid water is much greater than the density of the air. Assume a raindrop is spherical and has a diameter of 5mm. Determine its terminal velocity. Use the following procedure: a. Guess a velocity and compute the Re. b. Compute the Co. c. Use Figure 12.4 to see if your computed Co matches the correct Co for that Re. If not give an improved guess for your velocity. Continue this process until you arrive at the correct velocity.

Answer 1

brinen, a 18 *10 fo Wa 4 Solution DE..5mm = 0.005m Loeffiwent of viscosity of Air 5 Nis/m2 (PA) (Air) density a 1.2 kg/m² (Sw) density of Klater = 1000 kg/m² g -- 10 m/s² kleight of sain doop mg = 1839 Buoyancy force, (FB) = Terminal velocity; (v) (Foru due to) F'= bayon visiocity Flip FR - W less Neglecting force due to Air (fp =0). yu 6x you = A 28 apg We 78 4 tr Pag wla the every 2 8 ² Pq gn X V = 2 x (0.0025)ăx 1000 kg gx1.8 X 1015 10m m3 s? NIS 14p.= 103 pas 103 V = 771.6 mys Mewater a cay Let y = 771.6 m/s Re Dyf 0.005 * 777.6 x 1000 M Re 3858 X10 Re = 3.858 x 106 Re ) 105, the otfore it is turbulent flow for (d = 0.6 (it become constant) Turbulent flow

lets take velocity (1) = 0.0001 m/s Rea Dvs 0.005 x 0.0001 x 1000 10-3 M Re 0.5 < (6) (0) fig (a 24 (at low reynolds Number) Re 6= 24 48 015 12.4 is not poovided. so, I am calcul alculating some more values. let take velocity (v) = 10 m/s Re DvP 0.005 X 10 X 100 10-3 Re= 50000 For moderate Reynold Numbers (10< Re < 2x109) CD= 0.4 (constant) M

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