Parameters analysis in 2D - simulation experiments

Objectives and Hypothesis

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:

1. 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.
2. 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:



Some of the important parameters are summarized below:



The various geometry and mesh are created from journal file, by varying the flocculation tank height. All the FLUENT settings including turbulence model, boundary conditions, solutions schemes etc. can be found in a sample of report summary for h/b=2 case.

Results and Discussion

Click here for the results of the series of simulation experiments and parameter analysis, completely summarized in an Excel workbook. Only parts of the results are given graphically below.



preliminary simulation experiments

• To investigate the appropriate boundary condition settings and the convergence level

Simulations with various h over b ratios
According to the results of the preliminary simulation experiments, the simulation are design in following ways:

• Mesh generation
  • The mesh files for various h over b ratios are generated using the journal file
• Define the problem in FLUENT
  • Click here for a report summary of all parameters of FLUENT model
• Formulations of the performance parameters

  • Click !here^CFD tasks.ppt|width=32,height=32! for a summary of the derivation and formulation of the performance parameters

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.