Dr. Gao works in diverse areas in fluid mechanics, biophysics and materials through modeling and simulation. He is particularly interested in fluid-structure interactions in both passive and active soft matter systems. Examples include cytoskeletal network, bacterial suspensions, microgel particles, biological cells and vesicles, etc.  In these systems, motions of small particles change the ambient flow field, which reciprocally affects the particle mobility. In particular, in the active systems where particles (biopolymer, bacterium, etc.) are self-driven, the micro-scale particle-particle interactions can manifest themselves at the macro scale to generate collective dynamics, leading to rich physics and new phenomena. Furthermore, as inertia becomes important at finite Reynolds numbers, resolving the reciprocal coupling between the fluid and the moving solid structures may suggest mechanisms of engineering applications in transport, pumping, locomotion, as well as bio-inspired robot design and optimization.

To resolve the multiscale physics in complex-fluids systems, Dr. Gao integrates and develops ad-hoc numerical and theoretical tools from discrete particle simulations to continuum models. We work on the Cartesian grid methods (e.g., immersed boundary and fictitious domain), the sharp interface methods (e.g., finite element), the boundary integral method and slender-body theory, as well as fast summation methods that facilitate large-scale computation.