Validation CFD in ANSYS Fluent, Spring 2010

Validation Studies of Fluent Turbulence Models for Fluent Simulations of AguaClara Flocculators

Travis Stanislaus

Introduction:

The AguaClara water treatment project uses ANSYS Fluent computational fluid dynamics (CFD) software to simulate and analyze turbulent fluid flow in idealized models of flocculators in AguaClara water treatment plants. The flocculator simulations in Fluent are used to obtain turbulent kinetic energy dissipation rate, ε, and energy loss coefficient, K, between baffle in the flocculator for AguaClara design equations that determine the height of the flocculator, H, the spacing between baffles, S, the quantity of baffles in the flocculator, and flocculation performance, Ѳε^(1/3) , Ѳ is the residence time between two baffles. The results from Fluent are used in the design of AguaClara facilities, so verification and validation of the Fluent flocculator model and simulation has been conducted continuously since the time AguaClara began using Fluent simulations. Verification is determination of the degree the model being simulated is an accurate representation of the developer’s description and solution to the model. Validation is determining if the model is an accurate representation of the real world physics and intended uses of the model.

Acid Neutralizing Capacity - Spring 2010

Created by Chengfeng Wu, last modified by Lorna Ximena Aristizabal Clavijo on May 28, 2010

Abstract:

The Spring 2010 ANC team is continuing research with lime feeders where the Fall 2009 team left off. The original idea was to create lamellar sedimentation by placing a slanted tube on top of a vertical one and running water upwards through the reactor. With appropriate fluid velocities, one can maintain a fluidized bed of lime particles in the lower segment but prevent the vast majority of solid lime particles from leaving with the effluent (see 2009 design). This semester the team modified the reactor design in order to improve its performance and provide an easy way to feed lime while the reactor is running (see new lime feeder design).

Following the set-up described in each experiment found below with both the new apparatus and the old one, the team is conducting a series of experiments in order to determine which mechanisms are important in producing effluent saturated with lime for long periods of time. The tests are based on hypotheses which the team has developed over the course of the semester. Following the recommendation of previous ANC teams, the Spring 2010 team has tried to isolate variables and test them separately. In all of the experiments, the team has tried to vary only one parameter at a time so that comparisons between tests are more meaningful.

Plater Settler Spacing - Coupling Analysis, Spring 2010

Zachary N. Romeo

Abstract:

Floc roll-up occurs in tube settlers when the torque caused by a differential in the velocity profile exceeds the force of gravity whereby particles fall back out into the sedimentation basin. The Plate Settler Spacing team hypothesized that holding the length to diameter ratio in tubes of different diameters constant at 20 would decrease the capture velocity's sensitivity to flow rate. Two diameters representing the extremes in lamella spacing (23.5 mm and 6.35 mm) were tested in this experiment. Each experiment was run with the tube settler at two different heights (1.3 cm and 2.7 cm) above the floc blanket-clear water interface.

Plate Settler Spacing - Velocity Gradients, Spring 2010

Tanya Suntikul Cabrito

Stepping from previous research with velocity gradients, this experiment seeks to uncouple their effects on tube settler performance deterioration from those of the capture velocity. In the team's last experiments (detailed in Exploring the Coupled Effects of Capture Velocity on Settler Performance), it was hypothesized that maintaining a constant length to diameter ratio in tube settlers would minimize the effects of the capture velocity on performance.