Undergraduate Research
Biosolids Production from Wastewater
At one point in the Renton Wastewater Treatment Plant, polymer is added to make sludge flocculate before being sent to a centrifuge for separation from the water. It had been assumed by all (operators, designers, mixing specialists) that the flow was turbulent. However, it is a suspension, and two of our group (Albert Chang and Shauna Vince-Cruz) measured the viscosity, found a very low power-law index, and were able to show from data in Perry’s that the flow was laminar. Two others (Joanne Crompton and Thin Thin Swe) found a mistake in Perry’s. Different groups did 3D flow and dispersion calculations for the plant geometry, static mixers (Diana Chung and Nick Tapias), and rotating mixers (Toai Nguyen and Steve Huang).
Evaporation on Hypochlorite Solutions: Laminar or Turbulent Flow?
Dan Ho and Angelo Ambion estimated the evaporation rate of hypochlorite solution in one of the channels. To do that, they used material generated by Megan McCauley on the rate of evaporation of liquid pools. Her problem was brought to us by Emeritus Professor Charles Sleicher. He had published a paper that used turbulent flow theory to estimate the rate of evaporation, and his results differed significantly from those used by an engineer from DuPont. The difference turned out to be associated with the type of flow: If you have an atmospheric flow past a pool of liquid, is the flow the same as at the leading edge of a flat plate (as the DuPont engineer had assumed) or is the flow the same as if it were generated a long way off and the turbulent velocity profile is already established? The difference can be 50–100 times, and it makes a great difference in safety analyses when estimating the dispersion from a spill.
Process Simulation: Polymers and Aluminum Reduction
Dan Walker worked on modeling a viscoelastic polymer in FEMLAB. He tried to do in FEMLAB what my PhD students had done in the past by writing their own code. The result wasn’t entirely successful, which just goes to show you what a tough problem that was. Zudtky Wisecarver did 3D simulations that are pertinent to aluminum reduction cells.
Two of those students (Albert and Toai) were aggressive in approaching Sharpe Mixers for summer support and continued work this summer. It was exciting for me to see the synergy that happened with all these different, but related, projects.
