Joint Mechanical Engineering (MNE) and Engineering Applied Sciences (EAS) Seminar by Dr. David Henann
When: Friday,
March 30, 2018
2:00 PM
-
3:00 PM
Where: Textiles Building 105
Description: Joint Mechanical Engineering (MNE) and Engineering and Applied Sciences (EAS) SEMINAR
DATE:
March 30, 2018
TIME:
2:00 p.m. 3:00 p.m.
LOCATION:
Textile Building, *Room 105 (CSCVR Conference Room)*
SPEAKER:
Dr. David L. Henann, Assistant Professor of Engineering
School of Engineering, Brown University, Providence RI
TOPIC:
A Continuum Model for Steady Flows of Dense Granular Materials
ABSTRACT:
Dense, dry granular flows display many manifestations of grain-size dependence in which cooperative effects at the microscopic grain-level have an observable impact on the macroscopic flow phenomenology. In one class of phenomenology, the characteristic length-scales associated with dense granular flow velocity fields in a wide variety of geometries are strongly dependent on the grain-size. In a second class of phenomenology, dense granular materials display size-dependence of the flow threshold. For example, flows of thin layers of grains down an inclined surface exhibit a size effect whereby thinner layers require more tilt to flow. Neither of these classes of behaviors may be captured by local, scale-independent constitutive theories, and hence, the formulation of a predictive model for dense granular flow has proven to be particularly difficult. In this talk, we present a continuum-level constitutive model for steady flow - called the nonlocal granular fluidity model - aimed at filling this need. The key ingredient of the model is a grain-size-dependent, nonlocal contribution, in which flow at a point is affected by both the local stress as well as the flow in neighboring material. We then demonstrate that the model quantitatively captures the size-dependence of both steady flow fields and the flow threshold - i.e., the conditions under which steady flow is possible - by comparing model predictions to measurements from experiments and discrete element method calculations. Throughout, we emphasize the geometric generality of the model by considering flows in a wide variety of configurations, including annular shear flow, planar shear flow with gravity, vertical chute flow, inclined plane flow, heap flow, and all variations of annular split-bottom flow.
BIO:
David L. Henann is the James R. Rice Assistant Professor of Engineering at Brown University. He received his B.S. in Mechanical Engineering from Binghamton University in 2006, followed by his S.M. and Ph.D. in Mechanical Engineering from MIT in 2008 and 2011, respectively. After postdoctoral appointments at MIT and Harvard, he joined the faculty at Brown University in the fall of 2013. His research interests are in the area of theoretical and computational solid mechanics, focusing on the modeling of amorphous materials, such as metallic glasses, granular materials, and polymeric elastomers, and addressing issues of size-effects and multi-physics coupling. Henann is the recipient of an NSF CAREER Award and the 2016 Pi Tau Sigma Gold Medal from the American Society of Mechanical Engineers (ASME). He was honored for his teaching by the students of Brown University Tau Beta Pi with the 2016 School of Engineering Dedicated Faculty Award.
For more information please contact Dr. Jun Li, MNE Seminar Coordinator (jun.li@umassd.edu, 508-999-8692).
All are welcome and light refreshments will be served.
Students taking MNE-500 are REQUIRED to attend!
All other MNE BS and MS students are encouraged to attend! EAS students are also encouraged to attend!
Thank you,
Sue Cunha, Administrative Assistant
scunha@umassd.edu
DATE:
March 30, 2018
TIME:
2:00 p.m. 3:00 p.m.
LOCATION:
Textile Building, *Room 105 (CSCVR Conference Room)*
SPEAKER:
Dr. David L. Henann, Assistant Professor of Engineering
School of Engineering, Brown University, Providence RI
TOPIC:
A Continuum Model for Steady Flows of Dense Granular Materials
ABSTRACT:
Dense, dry granular flows display many manifestations of grain-size dependence in which cooperative effects at the microscopic grain-level have an observable impact on the macroscopic flow phenomenology. In one class of phenomenology, the characteristic length-scales associated with dense granular flow velocity fields in a wide variety of geometries are strongly dependent on the grain-size. In a second class of phenomenology, dense granular materials display size-dependence of the flow threshold. For example, flows of thin layers of grains down an inclined surface exhibit a size effect whereby thinner layers require more tilt to flow. Neither of these classes of behaviors may be captured by local, scale-independent constitutive theories, and hence, the formulation of a predictive model for dense granular flow has proven to be particularly difficult. In this talk, we present a continuum-level constitutive model for steady flow - called the nonlocal granular fluidity model - aimed at filling this need. The key ingredient of the model is a grain-size-dependent, nonlocal contribution, in which flow at a point is affected by both the local stress as well as the flow in neighboring material. We then demonstrate that the model quantitatively captures the size-dependence of both steady flow fields and the flow threshold - i.e., the conditions under which steady flow is possible - by comparing model predictions to measurements from experiments and discrete element method calculations. Throughout, we emphasize the geometric generality of the model by considering flows in a wide variety of configurations, including annular shear flow, planar shear flow with gravity, vertical chute flow, inclined plane flow, heap flow, and all variations of annular split-bottom flow.
BIO:
David L. Henann is the James R. Rice Assistant Professor of Engineering at Brown University. He received his B.S. in Mechanical Engineering from Binghamton University in 2006, followed by his S.M. and Ph.D. in Mechanical Engineering from MIT in 2008 and 2011, respectively. After postdoctoral appointments at MIT and Harvard, he joined the faculty at Brown University in the fall of 2013. His research interests are in the area of theoretical and computational solid mechanics, focusing on the modeling of amorphous materials, such as metallic glasses, granular materials, and polymeric elastomers, and addressing issues of size-effects and multi-physics coupling. Henann is the recipient of an NSF CAREER Award and the 2016 Pi Tau Sigma Gold Medal from the American Society of Mechanical Engineers (ASME). He was honored for his teaching by the students of Brown University Tau Beta Pi with the 2016 School of Engineering Dedicated Faculty Award.
For more information please contact Dr. Jun Li, MNE Seminar Coordinator (jun.li@umassd.edu, 508-999-8692).
All are welcome and light refreshments will be served.
Students taking MNE-500 are REQUIRED to attend!
All other MNE BS and MS students are encouraged to attend! EAS students are also encouraged to attend!
Thank you,
Sue Cunha, Administrative Assistant
scunha@umassd.edu
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