webswirl1My graduate, postdoctoral, and early faculty research included study of the fluid dynamics of solid particles suspended in fluids (liquids or gases), with special interest in phenomena at small Reynolds numbers, that is, small, slow, or highly viscous flows. Part of this work was aimed at understanding fluctuations in sedimentation, visualized as swirls in the image on the left, the underlying density and velocity fluctuations of which are important to characterize properly for accurate modeling of the macroscopic transport of the sedimenting particles. While I still occasionally work on problems in fluid dynamics, these research investigations have led me to a broader interest in simulation of microscopic and macroscopic models of various interacting particle systems, especially where they have direct applications to the physical, biological, or social sciences (as described elsewhere on this site). The main thematic goal throughout all of my research is to find simplified or reduced models and simulations to determine the properties or make meaningful visualizations of various systems and phenomena.

Nonaxisymmetric high-aspect-ratio ellipsoids under shear: Lowest-order correction for finite aspect ratios, F. Shi and P. J. Mucha,
Physical Review E 90, 013005 (2014).
A narrow-band gradient-augmented level set method for multiphase incompressible flow, C. Lee, J. E. Dolbow and P. J. Mucha,
Journal of Computational Physics 273, 12-37 (2014).
A new method for simulating rigid body motion in incompressible two-phase flow, J. Sanders, J. E. Dolbow, P. J. Mucha and T. A. Laursen, International Journal for Numerical Methods in Fluids 67, 713-732 (2011).
Velocity fluctuations in a low-Reynolds-number fluidized bed,
S.-Y. Tee, P. J. Mucha, M. P. Brenner and D. A. Weitz, Journal of Fluid Mechanics 596, 467-475 (2008).
Velocity fluctuations of initially stratified sedimenting spheres,
S.-Y. Tee, P. J. Mucha, M. P. Brenner and D. A. Weitz, Physics of Fluids 19, 113304 (2007).
Statistical reconstruction of velocity profiles for nanoparticle image velocimetry, C. Hohenegger and P. J. Mucha,
SIAM Journal of Applied Mathematics 68, 239-252 (2007).
Diffusion-induced bias in near-wall velocimetry,
R. Sadr, C. Hohenegger, H. Li, P. J. Mucha and M. Yoda, Journal of Fluid Mechanics 577, 443-456 (2007).
Modeling of debris deposition in an extrusion filter medium,
C. L. Cox, E. W. Jenkins and P. J. Mucha, Proceedings of the 21st Annual Meeting of the Polymer Processing Society (2005).
A model for velocity fluctuations in sedimentation,
P. J. Mucha, S.-Y. Tee, D. A. Weitz, B. I. Shraiman and M. P. Brenner, Journal of Fluid Mechanics 501, 71-104 (2004) [sample animation].
A Stokes flow boundary integral measurement of tubular structure cross sections in two dimensions, M. Niethammer, E. Pichon, A. Tannenbaum and P. J. Mucha, Proceedings of the IEEE International Conference on Image Processing, 825-828 (2003).
Diffusivities and front propagation in sedimentation,                P. J. Mucha and M. P. Brenner, Physics of Fluids 15, 1305-1313 (2003).
Nonuniversal velocity fluctuations of sedimenting particles,
S.-Y. Tee, P. J. Mucha, L. Cipelletti, S. Manley, M. P. Brenner, P. N. Segre and D. A. Weitz, Physical Review Letters 89, 054501 (2002).
Fast fluid analysis for multibody micromachined devices,
X. Wang, P. J. Mucha and J. White, Technical Proceedings of the Fourth International Conference on Modeling and Simulation of Microsystems, 19-22 (2001).
That sinking feeling, M. P. Brenner and P. J. Mucha, Nature 409, 568-570 (2001) [News & Views].
Partial screening in dense lattice-configuration suspensions,
P. J. Mucha, I. Goldhirsch, S. A. Orszag and M. Vergassola, Physical Review Letters 83, 3414-3417 (1999).
On Zero Reynolds Number Microhydrodynamics of Particulate Suspensions, P. J. Mucha, Ph. D. Thesis, Program in Applied & Computational Mathematics, Princeton University (1998).