My research interests focus on the dynamics of complex systems. During my post-doctoral research, I worked mainly on the development of new numerical algorithms to simulate complex flows. Initially, my focus was aimed at environmental applications (reactive flow in porous rocks as part of the CO2 sequestration initiative). More recently, my interests shifted towards applications in biologically motivated areas. I co-developed a new approach to simulate dynamically a fluid coupled to an elastic solid (so-called fluid-structure interaction). This approach can be applied to study topics ranging from blood flow in the cardiovascular system to flutter in aircraft wings. Currently, I am combining the model to a Brownian Dynamics algorithm aimed at simulating chemotaxis and the collective behavior of swimming microorganisms. In my poster I will focus on my current research. In addition, I will briefly summarize my previous research accomplishments and outline my future interests.

The past two years, I co-developed a new technique for modeling fluid-structure interactions that captures the dynamic coupling between a fluid and an adjacent compliant bounding surface. This technique is of particular relevance to the modeling of microencapsulated fluids. (Microcapsules consist of an agent enclosed in an elastic shell and are becoming increasingly important in the pharmaceutical, cosmetics and food industries.) However, the same technique is also appropriate to model a variety of biological cells, their mutual interactions, and the interaction between individual cells and a (compliant) confining substrate. The algorithm uses a lattice-Boltzmann model for the fluid flow and a lattice-spring model for the elastic shell and the substrate. More recently, I coupled the method to a Brownian dynamics model to simulate a suspension of nanoparticles that are small enough to be treated as so-called tracer particles. (I will use the name tracer particles to indicate either a dissolved chemical component or particles that are small enough to be treated as mutually non-interacting particles without excluded volume.) The combined algorithm captures the complete and explicit coupling among the Navier-Stokes equation for the fluid phase, the convection-diffusion equation for the tracers, and the continuum equations for an elastic solid for the shell and the substrate.

I will illustrate the method by simulating the release of nanoparticles from a microcapsule as it rolls along an adhesive substrate, as well as the subsequent particle adsorption on the wall. Starting with the simplest case of a planar perfectly adsorbing substrate, I examine how the rate of adsorption is affected by the adhesion strength between the capsule and the substrate and the membrane stiffness. I will show that even for this simple system, the compliant nature of the capsule significantly affects the rate of deposition at the surface. I will then exploit the fact that the adhesion strength between the capsule and the substrate could be different for an "untreated" surface and a surface with a coating of nanoparticles and discuss how this could be utilized to repair a damaged area. In particular, I will show that an uncoated area of the substrate can act to arrest the motion of the microcapsule, thus localizing it near the damaged region. Releasing new nanoparticles from the microcapsule then allows one to "repair" the area, before the capsule continues its motion along the surface. Thus, the findings yield guidelines for efficient localized delivery of an active ingredient onto a substrate. The ability to regulate and localize the delivery of nanoparticles or reactants to specific areas at a substrate can allow researches to design effective micro-scale delivery systems.