Granular flow simulations earn Dan Negrut NSF CAREER award
n summer 2008, 12 African American high school students from Madison, Milwaukee and Chicago spent a week on campus with Assistant Professor Dan Negrut. The students participated in a pilot program designed by Negrut to promote computational science, engineering and college in general.
In addition to being a fun experience for the students, the program, dubbed Promoting the Computational Science Initiative, or ProCSI, attracted the attention of the National Science Foundation, which awarded Negrut a prestigious 2009 Faculty Early Career Development Award (CAREER). CAREER awards recognize faculty members who are at the beginning of their academic careers and have developed creative projects that effectively integrate advanced research and education.
Negrut’s high school program exposes students to the work of his team at the UWMadison SimulationBased Engineering Laboratory. The lab focuses on using computer modeling and simulations to understand the dynamics, or motion, of complex mechanical systems. One of the group’s projects is to calculate granular flow dynamics with highperformance parallel computational hardware.
Negrut and his students have developed simulations that can calculate all the collisions between 10 million bodies, such as grains of sand, in as little as four seconds. To do this, the team uses parallel processing units that execute commands simultaneously, rather than sequentially as in regular computer processors. The parallel solution developed by Negrut can perform a multimillion body collision detection task about 40 times faster than can a regular computer. (For simulation movies, see sbel.wisc.edu/Animations/index.htm.)

Assistant Professor Dan Negrut (back row) poses with high school students at the inaugural session of ProCSI.

The next step for Negrut’s research is to compute the friction and contact forces between grains by solving differential equations that explain exactly how each grain moves and interacts with other grains. Solving dynamics equations with parallel computers has applications far beyond granular material, as differential equations are used in a broad range of engineering problems. For example, Negrut’s research could eventually be used to look at the movement of atoms. For now, his work has applications in construction vehicle and military vehicle design, and he has ongoing projects with P&H Mining of Milwaukee and the U.S. Army.
Negrut is also collaborating with Professor Alessandro Tasora from the University of Parma, Italy, and Mihai Anitescu, a computational mathematician from Argonne National Laboratory. This summer, Negrut will spend a month working at the mathematics and computer science division at Argonne, and next November he will travel to Italy for a week.
How does Negrut make his research accessible to high school students? He explains problemsolving as a stepbystep process where each component builds on itself. The first day of ProCSI, the students learn about mechanical engineering problems. The next day they learn how math is used to solve engineering problems. Then they learn how computers can be used to solve the math that solves the engineering problem. On the final day, the students learn how to put all of the problemsolving components together and actually run simulations themselves. Thanks to the CAREER award, Negrut will be able to continue this program for the next five years.
 