Prof. Robert C Armstrong

Research Interests:

Theoretical, computational, and experimental methods are being used to elucidate the rheology and fluid flow characteristics of non-Newtonian fluids. A wide variety of fluids are being studied including dilute polymer solutions, concentrated polymer solutions and melts, liquid crystalline polymers, concentrated suspensions, biodegradable polymers, and composites of rigid fillers and polymers. For many of these systems we are developing structural and molecular models which are of great importance in interrelating the microstructure with processing conditions, and in understanding the physics of these flows at interfaces.

We are also developing numerical methods for solving viscoelastic flow problems. The finite element method is currently being used to solve confined and free surface flow problems for differential and integral viscoelastic fluid models, and for molecular and structural models for polymer solutions, liquid crystals, and suspensions.

Some very exciting work is underway in our group to couple efficiently simulation of the macroscopic flow with evolution of the underlying molecular configurations. Efforts are also aimed at matching computational results with experimental results obtained by applying laser Doppler velocimetry, video imaging, birefringence, NMR, and standard rheometry to investigate model flows of these materials.

The group has excellent facilities for carrying out non-Newtonian fluid studies. For numerical studies we have numerous minicomputers and graphics workstations. For large calculations, we have easy access to state-of-the-art supercomputers. Experimental facilities include a six-beam, three-color laser Doppler velocimeter, a two-color laser birefringence apparatus, a Rheometrics Mechanical Spectrometer, an elongational flow viscometer, a biaxial extensional flow device, a high shear rate capillary viscometer, and numerous flow loops.