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Parameters analysis in 2D - simulation experiments
Objectives and Hypothesis
Based on our understanding of flocculation model, we use Pi-cell, G-theta and epsilon-theta as important design parameters that characterize the performance of hydraulic flocculation tanks. By comparing the performance parameters that derived from or assumed according physical understanding or intuition with the values that are calculated from the discrete numerical solutions from CFD simulation, we want to verify the validity of the flocculation model and draw more insights of how to design hydraulic flocculators.
Methods and Procedures
The preliminary simulations had encouraging outcomes about the dependence of performance parameters on h/b ratio. In further experiments described below, we simulated a series of cases with h/b ratio of 2, 3, 4, 5, 8, 10, 15, 20 and 40 and plotted each performance parameters as a function of h/b ratio. We would expect:
- K_baffle is a measure of energy loss within each baffle spacing. It will converge as h/b ratio increases, and will also converge in a single baffle for successive turnings. Shultz and Okun has suggested its value is between 3 and 4.
- Pi_cell will increase as h/b ratio increase, which measure the active volume of flocculation tank. Pi_cell/(h/b) can be a measure of the active fraction of flocculation tank, which is expected to decrease as h/b ratio increases.
Methods and Procedures
h/b ratios of 2, 3, 4, 5, 8, 10, 15, 20 and 40 were tested with 5 baffles. The completed test are summarized in the following table:
preliminary simulation experiments
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Click here for a summary of the calculated
parameters
Pi_cell was shown to increase continually as h/b ratio increases in preliminary experiments, which was also reported in Fall 2008 research.