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The channels and ports that carry the flocculated water to the sedimentation tank need to be designed to have the same maximum energy dissipation rate as at the end of the flocculator.
*Create the geometry of the transition from the flocculator to the inlet channel of the sedimentation tanks.
*Determine the required flow area of the channel that produces the same energy dissipation rate as the baffles at the end of the flocculator. The AguaClara design team is currently using the equation
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{latex} \[\varepsilon \cong \frac{1}{{20W}}\left( {\frac{V}{{K_{vc} }}} \right)^3 \]{latex} |
where V is the mean velocity, W is the dimension of flow that the vena contracta narrows further,
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{latex}\[K_{vc} \]{latex} |
is the area ratio of the vena contracta (0.6). The coefficient of 20 is a rough approximation and needs to be determined using CFD. The energy dissipation is the maximum energy dissipation rate and it must be defined using a similar approach as will be used for the flocculator baffles. After this analysis is complete we can discuss the merit of doing additional analysis for the ports that carry water into the sedimentation tanks or the ports that release water from the sedimentation distribution tunnels. The expectation is that the equation above will predict the energy dissipation rate reasonably well for different geometries as long as the flow paths take a 90 degree bend.
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