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FESWMS: Questions regarding boundary conditions


T-CHG
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Hi!

I am trying to get a FESWMS model to run properly, which can be described as an inflow (constant discharge) which flows through a tributary into a larger area. From this area, there are multiple paths through, all having a known discharge/WSE relation. In order to get the model to run, I've for start used a constant, common, WSE as boundary condition in each of these paths.

Regarding this I have some questions and concerns:

1. I believe to have read somewhere in the help files that boundaries shall be defined from left to right in the flow direction. If this is the case, then why do I always have to reverse the direction of the boundary condition? (Also, after saving and exiting the model and restart it, ALL boundaries are doubled; showing arrows both into and out of the model. For tidiness, I delete the wrong ones before simulation, but it is irritating nonetheless.)

2. In the model described above I use a constant water surface elevation as a downstream boundary. In the preliminary simulation results, it looks as if only one actually works as a downstream boundary. The other WSE are constant, but no water seem to flow out through that boundary. (In one case it even looked as if water was flowing in from that boundary on to the next constant WSE boundary.) The option "make nodestring total flow string" is NOT active in any of the boundaries. The direction of the boundary is OUT from the model in all cases.

3. When the model works ok and I have managed to steer down approximately to the water surface I want, I would like to apply the discharge/WSE relations as downstream boundary condition. There is such an option under "computed water surface", but this also requires a discharge. If I have a discharge/WSE relation, a supplied discharge would in fact make it... a constant WSE boundary. This does not make any sense? Is it possible to use a discharge/WSE relation as a boundary condition?

Kind regards,

Fredrik

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