In Telemac 3D, for the settling velocity of sediments, we can use either 'settling velocity of sands' or 'constant sediment settling velocity'. I also find that in the examples of Telmac 3D both can be used to describe non cohesive sediment. But I got different results for the same case using these two kinds. So can anyone tell me the difference? Especially in which situation (e.g. modifying other keywords), 'settling velocity of sands' has the same effect just like 'constant sediment settling velocity'?