Gtheta Computations using UDF
A User Defined FLUENT script (UDF) was created to extract the G_theta value from the flocculator. The UDF loops through all of the individual cells of the converged solution, and extracts the energy dissipation^1/2 times the cell area. The sum of this quantity for all cells divided by flow and square of viscoisty results in the G_theta value of the entire flocculator as shown in equation 1.
Gθ_baffle=1/Q*vis^(-1/2)*∑(ε^(1/2)*cell_area) Eq. 1
The above formulation has been determined (with Monroe's help) by weighting the value of Gθ by volume.
The Gθ_baffle values weighted by the area or number of cells were also examined, but these formulations do not produce sensible results.
Below is the G_theta value presented for flocculation tanks of different geometries:
Case Geometry (h-height,b-width,N-baffles) |
Gθ_Flocculator |
|---|---|
b=.1, h=1, N=1, Clearance height=.15 |
430 |
b=.1, h=.3, N=5, sym bc |
1330 |
b=.1, h=.2, N=5 |
1060 |
Understanding the Gθ parameter
The Gθ value increases with increasing flocculation tank volume. Thus comparing different designs, each case should be normalized by the volume or area for (2D geometries). This results in the following normalized values.
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