JUST THE RIGHT MIX
LSU, Dow working to optimize chemical mixing for better plastics, drugs

A cup of freshly brewed coffee starts the day for many Louisianians. Each cup may be refined with the right combination of cream and sugar, blended to perfection, making it more delectable. Blending these components is the key to creating that perfect cup of coffee, and the importance of this process of mixing and stirring is something LSU Turbine Innovation & Energy Research Center Professor Sumanta Acharya understands.

Acharya uses this common morning routine as a way to illustrate his study of stirred tank reactors for the chemical and pharmaceutical industries. Just like the perfect cup of coffee, Acharya and his co-workers are exploring strategies to find the best process and equipment to mix chemicals to achieve the optimal product, ranging from plastics to prescriptive drugs.

A stirred tank is the piece of equipment where two or more chemicals are mixed to react at a molecular level, producing products for medicines, automobiles, and homes. With funds from the Louisiana Board of Regents and Dow Chemical Company, Acharya is looking at how to predict mixing processes and design mixers, enhancing the efficiency of the process and ultimately maximizing the product's quality and quantity.

“There are enormous costs involved in building different tanks and the use of trial and error to see which is most efficient is not cost-effective; so we are using computational models to predict optimal flow and mixing,” says Acharya, also a professor in the Department of Mechanical Engineering.

By generating a computational model of a tank and the impeller blades, which do the actual mixing, Acharya is able to assign and solve equations representing various operations of the mixer, such as fluid flow, heat transfer, and chemical transport. Using algebra much more complex than most of us learned in high school, Acharya can better determine the transport of reactants and products inside the tank and predict how well the reactants are mixing.

For computations of this magnitude, Acharya and his students are using SuperMike in the Center for Computation and Technology and a computing cluster at the Dow plant in Plaquemine, Louisiana.

“I think this project would be impossible without parallel computing resources at LSU and Dow,” says Acharya.

Acharya and his team of graduate students are also working on further developing the computer code CHEM 3D, which will be used for stirred tank computations. The code originated at Dow from one of Acharya's former Ph.D. students, Albert Harvey. Harvey currently leads Dow's computational fluids effort. CHEM 3D is a state of the art code specifically designed to run efficiently on large parallel computing platforms and is considerably more versatile and efficient than most of the commercial codes that currently exist. Acharya's team will further develop the code, which will be used both by LSU and Dow, and demonstrates how the University partners with industry to foster economic development.

ON THE WEB:
LSU Department of Mechanical Engineering
The Dow Chemical Company

from Winter 2005