4H 



HYDRAULICS AND ITS APPLICATIONS 



Ho\v towards the central portion of this face, to make good the loss of 

 fluid abstracted by the eddies at its sides, the state of affairs being 

 represented in Fig. 23 A. 



Where the body extends from the surface to the bottom of the stream, 

 so that the motion is sensibly in two dimensions, the eddy formation is a 

 discontinuous process. In such a case eddies may be formed either 



FIG. 23. 



simultaneously at each edge, or alternately at the two edges of the body 

 as shown in Fig. 23 B. 



The eddies as first formed are small, and gradually grow until suffi- 

 ciently large to impede the rearward flow in the wake which is necessary to 

 feed them. They then break away and join the procession of eddies 

 forming the boundary of the wake. 



When formed in three dimensions, eddies may be produced either 

 continuously or discontinuously. In the former case they are at different 

 stages in their growth at different points of the perimeter of the body, and' 



