The Faculty

Focus

Nonlinear dynamics, fluid dynamics, condensed-matter physics, biologically inspired physics

Education

Ph.D., Harvard University, Engineering Sciences 2001

Thesis: Singularities in free surface flows. (Advisor: H. A. Stone) Part III Mathematics (M.Sc. equivalent), with Distinction

1997

Cambridge University, Department of Applied Mathematics & Theoretical Physics

Honors A.B., magna cum laude, Phi Beta Kappa, Harvard University, Physics

1995

Honors & Awards

A. P. Sloan Foundation Fellowship 2006

NSF Mathematical Sciences Postdoctoral Research Fellowship 2001-2003

Harvard Graduate School of Arts & Sciences Merit Fellowship 2000-2001

National Science Foundation Graduate Fellowship 1997-2000

Herschel Smith Harvard Fellowship 1996-1997

Research Interests

I am interested in the formation of singularities, e.g. divergences in physical quantities such as pressure, on a fluid surface due to flow and surface tension effects. Two examples are the breakup of a liquid drop and viscous entrainment. In studying how nonlinear interactions give rise to singularities, we hope to understand the kinds of simplification in dynamics that can result when a physical process involves disparate length- and time-scales. We also hope that surface tension effects can be used to create structures which span a few molecules in one dimension but are macroscopic in other dimensions. More generally, thin tendril-like structures which extend over large distances arise in many contexts and can often strongly influence the large-scale dynamics. Examples include thermal and compositional convection, Coulomb fission and the formation of tether structure on a fluid surface due to optical radiation pressure. We use analytical methods, often based on asymptotic analysis, and numerical simulations. Many of the work are inspired by, or happen in parallel with, experimental work.

Selected Publications

1. W. W. Zhang, H. A. Stone & J. D. Sherwood, Mass Transfer at a Microelectrode in Channel Flow.  J. Phys. Chem. 100 (22), 1996, 9462-9464.

2. W. W. Zhang & H. A. Stone, Oscillatory Motions of Circular Disks and Near-Spheres in Viscous Flow.  J. Fluid Mech. 367 1998, 329-358.

3. W. W. Zhang & J. R. Lister, Similarity Solutions for Film Rupture on a Plate. Phys. Fluids 11 (9) 1999, 2454-2462.

4. W. W. Zhang & J. R. Lister, Similarity Solutions for Capillary Pinch-off in Fluids of Differing Viscosity.  Phys. Rev. Lett. 83 (6) 1999, 1151-1154.

5. R. F. Ismagilov, D. Rosmarin, P. J. A. Kenis, W. W. Zhang, H. A. Stone, & G. M. Whitesides, Pressure-Driven Laminar Flow in Tangential Microchannels: an Elastomeric Microfluidic Switch. Anal. Chem. 73 (19) 2001, 4682-4687.

6. J. Zebrowski, V. Prasad, W. W. Zhang, L. M. Walker & D. A. Weitz, Shake-Gels: Shear-Induced Gelation of Laponite-PEO Mixtures.  Colloid & Surface Sci. A, 213 2003, 189-197.

7. P. Doshi, I. Cohen, W. W. Zhang, P. Howell, M. Siegel, O. A. Basaran, & S. R. Nagel,  Persistence of Memory in Drop Breakup: The Breakdown of Universality.  Science, 302 2003, 1185-1188.

8. W. W. Zhang, Viscous Entrainment from a Nozzle: Singular Liquid Spouts.  Phys. Rev. Lett., 93 2004, 184502.

9. L. Xu, W. W. Zhang & S. R. Nagel , Drop Splashing on a Dry Smooth Surface. Phys. Rev. Lett., 94 2005, 184505.

10. W. W. Zhang & D. R. Robinson, Balance of Actively Generated Contractile and Resistive Forces

Controls Cytokinesis Dynamics. Proc. Natl. Acad. Sci. USA, 102 2005, 7186-7191.

11. K. S. Turitsyn, L. Lai, & W. W. Zhang “Asymmetric disconnection of an underwater air bubble: Persistent neck vibrations evolve into a smooth contact”,  Phys. Rev. Lett. 103, 124501 (2009).

12. L. E. Schmidt,  N.C. Keim,  W. W. Zhang & S. R. Nagel, “Memory-encoding vibrations in a disconnecting air bubble”,  Nature Phys. 5 343-346 (2009).

13. F. Blanchette & W. W. Zhang,  “Selective withdrawal in liquids of uneven viscosities”, Phys. Rev. Lett. 102 144501 (2009).

14. R. D. Schroll, C. Josserand, S. Zaleski and W. W. Zhang, “Impact of a Viscous Liquid Drop,” Phys. Rev. Lett. 104 034504 (2010).

15. J. Freed-Brown, J. M. Amundson, D. R. MacAyeal and W. W. Zhang, “Blocking a wave:  frequency band gaps in ice shelves with periodic crevasses,”  Annals of Glaciology 53 60 (2012).

BPHYS Students

Samantha Stam