2D Performance Parameters Analysis

Goals 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 mesh of 2D models is swept in the z-direction with a width of 0.1m (lengthxheightxwidth(x*y*z) = 0.2*1*0.1), and a mesh interval size of 0.002m (#intervals=50), which is in the same order of magnitude as that of x and y directions.

Preliminary Observations and Discussion (on-going simulation)

Since the finer mesh contains 1,500,000 cells, which is 50 times as many as that of the 2D mesh and 70 times as big as the 2D mesh in terms of the file size, the iteration takes about 30 seconds per step. After about 3000 iterations for 30 hours, the residual plots showed a promising tend to fall below a satisfactory level. (The simulations is still running at this moment)

(Still waiting for the more converged results for the energy dissipation contour...)

Residual plot at 3096th iteration with maximum scaled residual of about e-5

Energy dissipation contour at 3096th iteration with maximum scaled residual of about e-5, for the plane at mid-width