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ed February 16, 2007 02:12

Flow Split Setup Question
 
I'm working on a hydraulics problem looking at the flow split through a structure. I'm doubting my model results and looking on any thoughts or comments.

Water enters a channel, ~7.5 feet x 50 feet, from 4 ports along the long side, with the assumption that the flow is evenly split between the entrances. A second channel is downstream ~7.5x100 feet, connected to the influent channel via the ends and a small opening in the middle. There are 10 exits slots to tanks, with baffling across the tank width downstream from the slot along the second channel.

I've used pressure outlet boundaries on the downstream ends of the tanks. There is ~3" of headloss from the entrance to the exit. The model is run steady state with a rigid lid until the flow split stabilizes and the residual is less then 0.001. The solution is very close to symmetric about the centerline, but the flow distribution is much higher at the outside slots compared with the middle slots. I expect some distribution, but the results show a larger range than they should, I think.

Thanks,

Ed


Freeman February 16, 2007 17:55

Re: Flow Split Setup Question
 
so, the flows enters through 1 and 'supposely' be splitted evenly among 4ports or ? if that's the case, then there're alot of factors among which are: 1.the dia/sectional areas are not the same. 2.depending on the 'dynamics' or shape at the splitting section, the area which's more direct to the flow direction might probably takes more flow or vice versa. 3.how is the pressure distribution too? you might consider an 'out flow' bc for exit instead of pressure if possible.

if the bcs are specified at the 4ports, then it might be how it was specified. Fluent/gambit as you to specified the total mass flow for the 4ports and fluent will then distribute it among them automatic. This might not be trusted since it'll sense the loacal physics and then adjust accordingly. if the there're a lot of losses occuring in a particular vincity, it'll drain more flow. so you might consider specifying individual mass flow as bc if is possible.

i hope this helps. if u need any clarification or whatsoever drop me lines


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