Dr. Amy Shen was born in China and came to the United States for college. She studied engineering mechanics in China and got her masters in civil engineering at the University of Illinois at Urbana-Champaign. She then went on to receive her PhD in theoretical and applied mechanics from the University of Illinois. She now works at Harvard University in the division of engineering and applied sciences, and she has worked there since September.

Professional Interests

Dr. Shen does a lot of her work on the world of granular materials. She defines a granular material as “a collection of a large number of discrete solid particles with interstices filled with liquid or gas.” These are some of the unique characteristics of granular materials:

· Act as either a fluid or a solid

· Dilatancy

· Interactions between grains are dissipative

· Ordinary temperature plays no role

· The study of granular flow involves aspects of fluid mechanics, soil mechanics, plasticity, and statistical mechanics

Applications

There are many applications to her work. In industry, there are applications in pharmaceuticals, food processing, coal and mining, and powder metal forming. In nature, there are applications in river sedimentation, landslides, dune formation, and rock avalanches. The applications of Dr. Shen’s work are endless.


(these pictures of a water droplet, a collapsing silo, and a sand dune show where an understanding of granular flow could be applied)

One of the examples of Dr. Shen’s work involves a sphere being dropped onto a level plane of sand. The impacting sphere produces a cylindrical cavity in the sand. The cavity then collapses, and the sand converges axisymmetrically toward the center. A pressure spike drives up in the sand in a narrow jet along the axis of symmetry. Granular jets are usually about 50 grain-diameters wide.

Dr. Shen performed experiments where she dropped a certain sized sphere from different heights onto the level plane of sand, and she photographed it with a special camera to observe how the sand reacted. She recorded her data, and she used the following information in dimensional analysis to come up with an equation:

An Added Bonus: Experimental Method

Dr. Shen shared her insight on the experimental method and recommended following these basic steps when performing an experiment:

*describe an initial observation

*define the purpose of the experiment

*identify the variables

*make a hypothesis

*design experiments to test the hypothesis

*do the experiments and record the data

*perform calculations

*summarize the results

*draw conclusions based on the results

This webpage was created by:
Carolyn Robinson
Meredith Maltese
Jennifer Farrell