Vízügyi Közlemények, 1970 (52. évfolyam)

4. füzet - Rövidebb közlemények és beszámolók

Since several trials are necessary to determine from this diagram the corresponding values of critical slope and mean velocity pertaining to given waterdepth and bed-load material, Fig. 2 is suggested by the author as one from which the desired mean velocity is found in terms of the critical slope obtained from the ciritical parameters of Shields. Fig. 2. Plot of the quantities V

g , D/d and at the critical condition U

4 „2/3 g 1/3 Some of the investigators of sediment transportation phenomena appear to prefer dimensional analysis as a tool in solving their problems, while other reject it. The objections, as voiced repeatedly in the criticism, stem mainly from the fact that for its success dimensional analysis depends on the correct selection and grouping of independent variables influencing the phenomenon. Great circumspection, practice and in several cases ingenuity are undeniably required. The success of the method suggested by the author also depends on the correct choice of significant dimensional and dimensionless basic quantities, but the danger of using interdependent basic quantities is eliminated, these being dropped out by mathematical techniques from the analysis [26]. New methods of investigation, or new instruments are capable of revolutionizing a branch of science (for instance medicin by the introduc52