Saltation and Suspension Trajectories of Solid Grains in a Water Stream

30 trajectories 385 photographs analysis Bagnold bed grains bed particles Carlton House Terrace cm/s coefficient coefficient of drag coefficient of friction collision crest curve depth 4.8 cm du/dy effect equation figure 11 fixed bed flash intervals fluid impulses fluid thrust fluid turbulence flume Francis frequency gives Grain acceleration grain density grains falling grains of set gravity gravity force height higher images impact increase Ippen lift force longer trajectories low trajectories main series mean forward speed mean value moving grain occurs parameter plotted points rolling mode Royal Society saltant trajectories set 2 grains shear drift force shear stress shear velocity shown in figure smaller solitary grains speed Ū started from rest still-water subdivided into saltations subsidiary experiment suspensive mode suspensive trajectories transport turbulence u/uo U₁ U₂ upward acceleration upward force upward impulses velocity gradient vertical acceleration Vg/u water stream y/cm Ymax/cm