Information About

Seth Lichter Professor Dept. of Mechanical Engineering Northwestern University 2145 Sheridan Road, Rm. L396 Evanston, IL 60208-3111, USA TEL: 847-467-1885 FAX: 847-491-3915 s-lichter@northwestern.edu link to research site AB Mechanical Engineering, Harvard (1973) MS(1975) PhD Mechanical Engineering, Massachusetts Institute of Technology(1982)

Honors and Awards

• Office of Naval Research Young Investigator Award
• Clemens Herschel Prize for Excellence in Engineering

Research: Fluid Dynamics, Hamiltonian Systems and Protein Folding

The guiding principle in our research is simplicity.  We are drawn to problems which are so complex that others study them using the most advanced and sophisticated numerical approaches.  What we try to do, is find simple analytical solutions for these unwieldy problems.  Actually, we often don’t seek to find a solution, just as much of one as possible.  For computers are very efficient at finding a solution once they are brought in the close vicinity of a solution.   Computers are hugely inefficient at finding a solution if they have little information on where to search for the solution.  So, our analysis seeks to provide, if not the full solution, then to provide 50% or even just 10% of the solution so as to allow numerical solutions to start with a good idea as to where to go to find the complete solution.  With this partial information as initial condition, numerical schemes are vastly faster.  For example, the usual computer routines for finding protein structures may take many days or months.  But, with some of our analytical advice, we hope, that this time can be reduced to hours or minutes.

We have applied this basic philosophy of looking for simple analytic solutions to complex problems in the areas of turbulence, many-body problems, slip of liquids over solids, and protein folding.

In the classroom

Next year, I’ll be teaching a new course on Modeling Energy in Society.  As you know, energy can neither be created nor destroyed.  So, there’s always enough energy!  But, it has to be processed and distributed.  This course treats the role of energy as a causative agent in the growth of society throughout history and how communities, held together by available energy, further enhance their growth and well-being by creating efficient energy infrastructures.  Rather than just reading about this fascinating and critical history, we will be formulating mathematical models and running numerical simulations to discover just how energy and society interact.

I teach an undergraduate course on Molecular Motors in Biology.  This course grew out of an interest of mine in the dynamics of proteins.  Check out the course web page which has interactive applets showing how polymers grow and molecular motors move.
http://www.mech.northwestern.edu/courses/389.S02/mmpage.html

I also teach a graduate-level course on Nonlinear Dynamics.  This is an interdisciplinary course, one of the few at the university (perhaps the only one!) which is cross-listed in eight departments both here in the Engineering School as well as in the School of Arts and Sciences.  Not only do we get to learn new techniques for solving equations, the students, appropriate to their diverse backgrounds, apply these techniques to a range of applications from looking at the spiral patterns on cacti to modeling global warming.  See a few of the topics we’ve studied by clicking here.

Cell Division - Tyson Model

 
It has been known for a while that there is a pattern of misunderstanding among students in introductory science classes (e.g. see “A Guide to Introductory Physics Teaching,” by A. B. Arons or C. Singh, in Am. J. Phys. 69: 885 (2001)).  In particular, it is found that for each subject, there is a set of conceptual errors that persist from year to year.  (Much like, as I have found from my 6-year old, that jokes that I learned in first grade, are still being learned in first grade.)  So, rather than ignore these persistent errors year after year, teaching can be made more effective if these difficulties are tabulated and directly addressed.  An undergraduate and I went through the material in my undergraduate course on Thermodynamics and Statistical Mechanics.   We uncovered where and why confusion arose.  We then formulated a teaching plan which directly addresses potential misunderstandings.  This is an ongoing project of mine in this course.  With each year, my list of conceptual potholes gets more complete and I can better steer the course around them.

A group of us in the Mechanical Engineering Department, got together a few years ago, and recognizing the potential for growth of new technologies relying on fluid flows through extremely small devices, established a sequence of three courses dealing with small-scale flows.  My course deals with the smallest possible scales, Molecular-Scale Fluid Dynamics.

Selected publications

When is a 1-dimensional lattice small? (with C.Y. Lin, S.N. Cho, and C. G. Goedde) Phys. Rev. Ltrs. 82: 259-262 (1999).

Unsteady Wetting on a Rough Surface due to Electrically Altered Surface Tension (with Y-Y Perng) J. Colloid Interface Sci. 217:119-127 (1999).

Interacting Vortex and Vortex Layer: How Length Scale Affects Entrainment and Ejection (with O. V. Atassi & A. J. Bernoff) AIAA J. 36: 924-928 (1998).