The primary focus of my research group is on nonequilibrium behavior of complex fluids, such as colloidal suspensions, emulsions, foams, and macromolecular solutions. I am also interested in the dynamics of granular materials and glass-forming matter. All these systems have complex nonequilibrium macroscopic properties that arise from the coupling of the motion on the macroscopic and microscopic scales. 

Complex fluids and granular matter are commonly found in nature (e.g., milk, cytoplasm, groundwater, sand) and in industry (powders, paints, drug delivery systems, cosmetic products). A better understanding of nonequilibrium behavior of these systems is thus important for applications that include design of new microstructured materials, development of new particle segregation methods, and control of particulate flows. Moreover, investigations of their nonequilibrium behavior pose many exciting and challenging fundamental theoretical problems. 

Examples of microstructural features with important  dynamic consequences include  shapes and ordering of drops or bubbles in emulsions and foams, conformation of macromolecules in polymeric solutions, and correlations between particles in colloidal suspensions. Due to a relatively large lengthscale and long relaxation time, the microstructure can be substantially distorted even by a weak applied stress. Thus, complex fluids and granular media are often termed "soft condensed matter." 

Under flow conditions, complex fluids may undergo shear thinning (i.e., a decrease of viscosity with increasing shear rate) due to alignment of the microstructure with the flow. At higher shear rates, the same fluid may exhibit shear thickening due to jamming of particle clusters. Jamming is also responsible for slow relaxation timescales in glassy materials, and is important in the flow of granular matter. For complex fluids confined in channels or pores (e.g., in microfluidic devices), additional complexity arises due to microstructural changes induced by the confinement. 

My research group is focused on theoretical and numerical studies. I also collaborate with several experimental investigators. Our current research projects include:  

Hydrodynamic confinement effects in complex fluids 
Dynamics in highly-asymmetric bidisperse colloidal suspensions 
Drop dynamics and emulsion rheology 
Jamming in particulate systems

Selected Publications:

"Many-particle hydrodynamic interactions in parallel-wall geometry Cartesian-representation method," S. Bhattacharya, J. Blawzdziewicz, and E. Wajnryb, Physica A, 356, 294 (2005). pdf

"Random close packing revisited: Ways to pack frictionless disks," N. Xu, C. O'Hern, and J. Blawzdziewicz, Phys. Rev. E, 71, 061306 (2005). pdf

"Sharp scalar and tensor bounds on the hydrodynamic friction of arbitrarily shaped bodies in Stokes flow," J. Blawzdziewicz, E. Wajnryb, J. Given, and J. B. Hubbard, Phys. Fluids, 17, 033602 (2005). pdf

"Phase equilibria in stratified thin liquid films stabilized by colloidal particles," J. Blawzdziewicz and E. Wajnryb, Europhys. Lett., 71, 269 (2005). pdf

Complete list of publications