CTS-9707778 R.G. LARSON UNIV. OF MICHIGAN SUMMARY Brownian dynamics simulations will be performed to predict the stretching behavior of long DNA molecules in simple flows, including uniform extensional, uniform, shear, and plane Poiseuille flows. The results of these simulations will be compared directly with experiments on single long, fluorescing, molecules of DNA in corresponding simple flows. The research will consider the transient process by which long polymer molecules stretch out in extensional or shear flows, and determine whether or not the physical forces that describe uniform flows at steady state work for the complex unraveling transient flow processes. The simulations, when combined with the experimental results, may also help explain why light scattering studies indicate little polymer stretching in such flows. These studies have applications not only in traditional areas of polymer fluid mechanics, Such as turbulent drag reduction and now through porous media, but are also relevant to Technologies involving DNA micro-manipulation, including the new technology of "fluid fixation", i.e., the use of hydrodynamic flows to stretch long DNA molecules to aid in genetic mapping.
