Different geometric scales have different effects on model flow and sediment motion characteristics,so does with model sand wave similarities.Firstly,for model sand that is satisfied with incipient motion similarity,the variation laws of settling velocity deviations with different geometric scales are numerically analyzed when prototype sand diameter,λ(γs-γ)/γandηare the same.The results showed that for the case ofλlλl≥1,the settling velocity deviations of model sand rise firstly and then fall with the increasing geometry scales,reaching its peak when the geometry scale is 2.Besides,to better understand model sand similarities at a large settling velocity deviation and deviation characteristics of model sand wave height and length from those of the prototype at different geometry scales,the normal flume experiments are designed withλl=0.84,1.59 and 2.06,respectively.The results represented that both sand wave height deviation and sand wave length deviation were less than 6 % in these three experiments.The sand wave withλl=0.84 was relatively smaller while the sand waves withλl=1.59 andλl=2.06 were relatively larger.Finally,the following conclusions were reached by integrating theoretical analysis with flume experiment methods:1） for geometric normal model,whenλlλl≥1,the settling velocity of model sand was relatively larger,resulting in a greater sediment deposition rate.Moreover,both sand wave height length were larger than those of the prototype.2）Whenλl≥1 and both sand wave height deviation and sand wave length deviation were less than 6 %,the model sand wave height and length had satisfied similarities.
