~ -r-

Since blocks 1 and 2 are in the same flow channel, we have ~ql = ~q2. Since blocks 2 and 3 are within the same equipotential lines we have ~h2 =~h3' If these equations are inserted we obtain the following relationship:

~ql =~q2 and M 1 =~~ This proves that the same quantity flows through each block and there is the same head drop

in crossing each block if all the blocks are squares or possess the same ratio alb. Flow nets are constructed by keeping the ratio alb the same in all figures. Square flow nets are generally used in practice as this is easier to construct.