(77e) Progress on Mixing at Dow Inspired By Doug Leng

Doug Leng was Dow’s first mixing expert and an inspiration and mentor for many young researchers interested in fluid dynamics and mixing. When I first met him in the mid-1980s he was a Senior Research Scientist and Laboratory Director of the Central Research Engineering Lab; the only person in the company to have these two high positions on both the technical and managerial ladders. In this talk, I will describe two areas in which Doug inspired and mentored me. I first met Doug about 1987 to seek his advice on a project for expanding Dow’s capacity for a raw material (chloroform) used for making so-called soft hydrochloro­fluorocarbon refrigerants. The results from research that he had led at the FMP consortium provided a key piece of information needed for designing a reactor capable of increased chloroform production. Some years later he sponsored the development and growth of computational fluid dynamics at Dow. My group benefited from this, especially his support for a unique code written by Bert Harvey which solved the governing equations for laminar flow in a rotating coordinate system. This made it possible to accurately simulate flows in stirred tanks for the first time, accuracy that was established by comparison with detailed velocity-field measurements made in Doug’s lab. In collaboration with Doug, we used this capability to design a new impeller which doubled the capacity of one of our polymer plants. Bert and I later developed the first method for computing the mixing time in laminar stirred tanks. In this we converted the computationally intractable problem of solving the time-dependent species transport equation into the problem of iterating a Poincare map; a calculation that could be accomplished in only a few minutes. In this talk, I will describe this problem and solution in some detail.