Granular Impact Cratering: Physics seminar

Lecture/Seminar - Natural Sciences | March 8 | 10:30-11:45 a.m. | 267 Classroom Building

Location:  5200 North Lake Rd, Merced, CA 95343

Speaker/Performer: Professor Douglas Durian

Sponsor: School of Natural Sciences

Professor Douglas Durian offers a physics lecture entitled "Granular Impact Cratering."

Experiments on the low-speed impacts of solid objects into granular media have been used both to mimic geophysical events and to probe the unusual nature of the granular state of matter.

Observations have been interpreted in terms of conflicting stopping forces, reminiscent of high-speed ballistics impacts in the 19th and 20th centuries, when a plethora of empirical rules were proposed.

To settle this controversy, we have measured the projectile dynamics during impact and have reproduced prior observations and found that the stopping force can be decomposed into the sum of velocity-dependent inertial drag plus depth-dependent friction.

Furthermore, by changing the projectile shape and imposing an upflow of air through the granular medium, we have established that friction acts normal to the projectile surface and that grain contacts are loaded by gravity rather than by the motion of the projectile.

Event Contact: Professor Ajay Gopinathan, agopinathan@ucmerced.edu, 209-228-4048