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Sedimentation Tank Baffle

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Old   March 3, 2014, 02:25
Default Sedimentation Tank Baffle
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Baharan Molaie
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I'm trying to model a rectangular sedimentation tank, but baffles seems to have no effect on the model, I tried to use the baffle option and also I tried to define it as a solid object... should I consider any specific considerations?!
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Old   March 12, 2014, 22:08
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Jeff Burnham
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The mosikely reason the baffles aren't affecting the flow is that they may not be defined correctly. Baffles must be defined with one (1) "definition" (X-plane coordinate, for example), and then limiters can be added to cut the baffle down to the correct size (y-min, y-max, z-min, z-max, for example, if the definition is an x-coordinate). If you rotate the baffle, it is rotated around the origin, so rotated baffles are easiest to define about the origin and then translate them to their final location. Preprocess the simulation before you run it: view the output to check if the baffles are correctly defined and placed.
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Old   March 16, 2014, 07:28
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thanks
I also have some confusion about the inflow and outflow... I did a laminar model but the inlet and outlet volume rate are not the same... is there any option in the software that I could determine that?! (I need height of the water to stay constant but I could only assign the height in initial conditions)
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Old   March 19, 2014, 22:26
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Jeff Burnham
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If you don't want to predict the shape of the free surface, then set "no sharp interface" option. All cells will be filled with fluid. Put the z-max boundary condition at the fluid "surface" and set it to Symmetry type, or put a solid component over the free surface and set the friction coefficient = 0 for free-slip.

If inflow still does not equal outflow, check that you are not losing fluid through cracks in your geometry, that the mesh cells are as close to cubes as possible, that the boundary conditions are correct, and that the simulation runs long enough to reach steady state.

Good luck.
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