Learning Forum

[ahmed01]

[Rob]

Scour is a complex process, so you need to consider what is causing, and limiting the sediment removal. Equally, do you need to include the free surface in the model?

[ahmed01]

Yes , can help me pls .

[Rob]

With what? If you need the free surface you'll want multifluid VOF (if the sediment is granular) or VOF plus species (if sediment is more silt like).

[ahmed01]

But how can i simulate sediment in VOF i mean the properties of sand ,as we know the move of sediment transport by suspension and rolling, ( if we ignore this transportation and focus on depth of scouring can do it )

[Rob]

You need to figure out what mechanism is causing the scour. Whether sediment from upstream is refilling the hole and why the scour stops when it does. You missed saltation from the transport too: that's a real pain to try and model. If you read the Eulerian model assumptions you'll see why I'm not even thinking about rolling.

[ahmed01]

Really is hard to model it ,but if we were patient we can get to what we want, then if we need to model this case (i mean scour, eg; scour around pier)by use the simplest way and to calculate the depth of scour we can use Vof if use free surface ?!(let we ignore cases of transportation of granular sidement)

[Rob]

I know it's hard, I've done it, or rather proved the concept so that someone else could do it. I'm also constrained by the rules so whilst I can guide you I can't share anything beyond what's public domain or in our manuals. Hence you needing to figure out what the scour mechanism is, and why the whole river bed hasn't disappeared.