Гидродинамика

ON SNOWDRIFTS When a s t a t i ona r y o b j e c t is met by a snowstorm, at some «distance l e e w a r d of the o b s t a c l e there is formed a heap of de­ p o s i t e d s n o w , wh i l e in f r o n t o f the obstacle there is formed a depr e s s i on . P r o f . J o uk ows k y gfives an explanation of this pheno­ m e n o n , a s s u m i n g f the o b s t a c l e t o be a cylinder of radius a, pro­ j e c t i n g a b o v e t h e snow, t h e a-sis of the cylinder being horizontal a n d norma] t o the d i r e c t i o n of wind. The current function =-ij-j->^2~ T ~ ( ^ ) fo'" t h e flow of air round such a cylinder i s obtained b y add i ng t o t h e current function 'l-i (2) characteri­ z i n g the v e l o c i t y of wind ix == — ш — '/-g near the ground in the a b s e n c e of t h e cylinder, t h e functions 'bo (3) and (4). If in the equa t i on '>o = c o n s t (7) of t h e lines of flow the constant is given t h e value r > there will b e obtained a dividing line of flow, m a d e up o f t h e c i r cumf e r enc e of a normal cross-section of the cy l i nde r a n d o f t he curve o f t h e fourth order (9), of which two branches AD a n d A'D' ( F i g . 1) have a horizontal asymptote j /i — ^ So» a n d the b r a n c h e s ВС and B'C have the asymptote = T w h e r e a n d are given by equation (11). This " A " c u r v e d i v i d e s all the lines o f f l ow into the following four groups, v i z , the l i nes o f f l ow d i s p o s e d a b o v e the line D'A' AD, the lines of f l o w d i sposec i beneath the l i n e CBB'C, the lines of flow enclosed within the c o n t o u r DABC, a n d the lines of flow enclosed within t h e contour D ' A ' B ' . To this f l o w there is a d d e d by Prof. Joukowsky also a flow w i t h the c u r r e n t function Ig ^ , which is due to the -' g 29 ' 17. — >1. /KyivoBCKiii i . Т о м III.