Soft Matter and Complex Fluids


Professor of Mechanical Engineering
Phone: (806) 742-3563 x 226 (office) 282 (lab)

Office: ME Room 111

Lab:    ME Room 217

elementary cell

Research Interests

The primary focus of my research group is on nonequilibrium behavior of complex fluids (e.g., colloidal suspensions, emulsions, foams, macromolecular solutions). We are also interested in the dynamics of granular materials and glass-forming matter.

Complex nonequilibrium macroscopic properties of such systems result from the coupling of the motion on the macroscopic and microscopic scales. 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.

Complex fluids and granular materials are commonly found in nature (e.g., cytoplasm, milk, sand) and in industrial applications (e.g., drug delivery systems, cosmetic products).  Nonequilibrium properties of soft materials have important implications for design of novel microstructured materials and development of new particle segregation methods.  Studies of soft condensed matter are also essential for understanding fundamental processes in living organisms.

Investigations of nonequilibrium behavior pose many challenging theoretical problems. Our research is focused on theoretical and numerical studies, but we also collaborate with several experimental investigators.

Complete list of publications

Research Areas

Microhydrodynamics                                                     More

Microparticles in complex fluids interact not only via direct potential forces but also through hydrodynamic forces mediated by the suspending fluid.   Evaluation of such forces requires solving Stokes equations in a complex multiparticle geometry.  Our group has developed efficient algorithms for evaluating such interactions for systems of spherical particles in free space and in the presence of a planar wall.  Our numerical procedures are used to study suspension transport in thin films and in narrow channels, and to investigate collective particle dynamics in confined suspension flows. 

Selected Publications:
S. Bhattacharya, J. Blawzdziewicz, and E. Wajnryb, Far-field approximation for hydrodynamic interactions in parallel-wall geometry. J. Comput. Phys. 212, 718, (2006). pdf

S. Bhattacharya, J. Blawzdziewicz, and E. Wajnryb, Hydrodynamic interactions of spherical particles in suspensions confined between two planar walls. J. Fluid Mech. 541, 263, (2005). pdf

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

Numerical Procedures

Confinement effects in suspensions                              More

Our recent investigations of suspension flows in parallel-wall channels demonstrated an unexpectedly rich phenomenology of strongly confined dispersion flows. For example, we have shown that flow reflected from confining walls produces transverse particle displacements resulting in enhanced particle diffusion. Our recent numerical studies also revealed  hydrodynamically induced pattern formation and order-disorder transitions in quasi-2D arrays of microspheres.  We are developing theoretical descriptions of these phenomena.

Selected Publications:

M. Baron, J. Blawzdziewicz, and E. Wajnryb, Hydrodynamic crystals: collective dynamics of regular arrays of spherical particles in a parallel-wall channel. Phys. Rev. Lett. 100, 174502 (2008). pdf and auxiliary materials (movies)

M. Zurita-Gotor, J. Blawzdziewicz, and E. Wajnryb, Swapping trajectories: a new wall-induced cross-streamline particle migration mechanism in a dilute suspension of spheres. J. Fluid Mech. 592, 447 (2007). pdf

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

Nonlinear dynamics of viscous drops                                More

Deformable viscous drops in external flow can be stabilized either by capillary forces or by drop rotation resulting from the vorticity component of the external flow.  Our recent theoretical and numerical investigations  revealed that the interplay between these two stabilizing mechanisms may result in bistable drop behavior and transition to chaos in flows with periodically varying vorticity.  We are studying this interesting nonlinear dynamics and investigating similar nonlinear phenomena that occur in macromolecules (e.g., DNA chains) deformed by an external flow.  Other thrusts of our research on drop dynamics include drop coalescence, emulsion rheology and collective dynamics of microdrops in microfluidic channels. 

Selected Publications:

P. M. Vlahovska, J. Blawzdziewicz, and M. Loewenberg, Small deformation theory for a surfactant-covered drop in linear flows. J. Fluid Mech. 624, 293 (2009). pdf

Y.-N. Young, J. Blawzdziewicz, V. Cristini, and R. H. Goodman, Hysteretic and chaotic dynamics of viscous drops in creeping flows with rotation. J. Fluid Mech. 607, 209 (2008). pdf

M. B. Nemer, X. Chen, D. H. Papadopoulos, J. Blawzdziewicz, and M. Loewenberg, Hindered and accelerated coalescence of drops in Stokes flow. Phys. Rev. Lett. 92, 114501 (2004). pdf

Glass transition                                                        

As temperature is decreased or density increased near the glass transition, the structural relaxation time in glassy materials increases by many orders of magnitude with only subtle changes in static correlations. Understanding the origin of this behavior is one of the most important outstanding problems in statistical physics.   We are studying this behavior using concepts of percolation theory, kinetic theory of dense fluids, and stochastic processes.

Selected Publications:

G. Lois, J. Blawzdziewicz, and C. S. O'Hern, A percolation model for glassy dynamics in disordered materials, Phys. Rev. Lett. 102, 015702 (2009). pdf

Thermoplastic forming of metallic glasses           

Certain liquid metallic alloys when cooled quickly enough retain non-crystalline amorphous microstructure.  These alloys, called bulk metallic glasses (BMGs), are exceptionally strong and have many other unusual properties.  In particular, they can be thermoplastically formed into a variety of shapes, with the structure controlled on multiple lenghscales ranging from macroscale to sub-nanometer scale.  In collaboration with experimental groups of Dr. Kumar at TTU and Dr. Schroers at Yale, our group is developing theoretical descriptions of processes involved in thermoplastic forming of BMGs, gaining insights into their nanoscale properties.

Selected Publications:

G. Kumar, J. Schroers, and J. Blawzdziewicz, Controllable nanoimprinting of metallic glasses: effect of pressure and interfacial properties. Nanotechnol. 24, 105301 (2013). pdf

G. Kumar, P. A. Staffier, J. Blawzdziewicz, U. D. Schwarz, and J. Schroers, Ultrasmooth metal surfaces through thermoplastic forming of metallic glass. Appl. Phys. Lett. 97, 101907 (2010).  pdf

Jamming in particulate systems                       

Although granular media are ubiquitous in nature (e.g., soil, sand, sediments) and in technological applications (e.g., powders, grains, pills), static and dynamical properties of such systems are still poorly understood. The problems studied by our group  include properties of static particle packings, and evolution of vibrated or slowly sheared granular media. Our goal is to develop quantitative descriptions of such systems, using concepts of equilibrium and non-equilibrium statistical mechanics.

Selected Publications:
G.-J. Gao, J. Blawzdziewicz, C. S. O'Hern, and M. Shattuck, Experimental Demonstration of Nonuniform Frequency Distributions of Granular Packings. Phys. Rev. E 80, 061304 (2009). pdf

G. Lois, J. Blawzdziewicz, and C. S. O'Hern, Jamming transition and new percolation universality classes in particulate systems with attraction. Phys. Rev. Lett. 100, 028001 (2008). pdf

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

Dynamics of biomolecules                                     

Proteins are biologically active macromolecules composed of a sequence of amino-acids connected into a long linear chain.  In its biologically functional native state, the chain is folded into a specific three-dimensional structure.  Our goal is to determine laws governing the folding process, and determine conditions for reliable folding into the native state. 

Selected Publications:

G. Lois, J. Blawzdziewicz, and C. S. O'Hern, Reliable protein folding on complex energy landscapes: The free energy reaction path. Biophys. J. 95, 2692 (2008). pdf

Research group


Frank Van Bussel

Graduate students

Alejandro Bilbao
Amar Patel

Former postdocs

Venkat Padmanabhan (IIT Kharagpur)
Martin Azese

Complex Fluids Group at TTU

Collaborators at TTU

Sukalyan Bhattacharya
Golden Kumar
Kendra Rumbaugh
Siva Vanapalli

Recent international collaborations

Eligiusz Wajnryb
IPPT PAN Warsaw, Poland

Maria Ekiel-Jezewska
IPPT PAN Warsaw, Poland

Zbigniew Adamczyk
ICSC PAN, Krakow, Poland

Francois Feuillebois
, France

Jan Dhont
IFF Juelich Germany

Mauricio Zurita-Gotor
Abengoa Research, Spain