Complex Fluids
Fascinating rheological properties like shear thickening/thinning and anisotropic viscosity arise from underlying structure in complex fluids. We develop and use techniques to simultaneously analyze emergent, large-scale properties and image particle-level positions and stresses in such suspensions.
Tunable solidification of cornstarch under impact: How to make someone walking on cornstarch sink
Embedding orthogonal memories in a colloidal gel through oscillatory shear
Stress decomposition in LAOS of dense colloidal suspensions
Tunable Shear Thickening
Shear thickening fluids like mixtures of cornstarch and water, or oobleck, are not only fun to play with but also have applications ranging from 3D printing to body armor and shock absorption. However, the rapid increase in the viscosity with the shear rate, the very property that makes these suspensions so interesting for industrial applications also leads to jamming and failure of processing equipment. Thus, it is essential to find a method to control and tune the viscosity of these shear thickening suspensions.
Here we discuss the various methods that we are working on to tune the viscosity of these shear thickening suspensions.
Using Acoustic Perturbations to Dynamically Tune Shear Thickening in Colloidal Suspensions
Quantitative Light Microscopy of Dense Suspensions: Colloid Science at the Next Decimal Place
Orientation Dynamics And Microscope Imaging Of Colloidal Suspensions
Fluids Under Confinement
Understanding the flow of complex fluids through confined spaces and forces governing the flow is key to diverse fields, from blood flow to lubricant design. Studying such situations is difficult because typical devices cannot achieve the necessary degree of confinement. New experiments and simulations reveal flow behavior under different levels of confinement and show how this behavior can be tuned.