Page 37 - ASME IMECE 2015 Program

Track Plenary

operating data can be incomplete and difficult to analyze, so tools for data made seminal, cross-disciplinary, and ground-breaking contributions to
reconciliation and diagnostic analysis need to be further developed and the permanent literature in mechanical engineering on multiphase flow
deployed. In cases where operating data are not available to validate and transport with wide applications in diverse areas of industry, health-re-
designs, CFD and experimental data can be used to validate performance. lated fields, atmospheric sciences, and many others. These include
As process efficiencies improve, the temperature difference between the studies of phase-change heat/mass transfer (condensation, evaporation,
hot and cold fluid streams tends to decrease, a result which encourages combustion, adsorption, and desorption with moving droplets and
increased application of enhanced heat transfer techniques. This, in turn, bubbles), ionized arc-plasma transport, non-Newtonian fluid flow/transport
requires ever more accurate predictive methods and a better understand- in vessels, squeezing flows of power-law fluids, capillary flows in grooves,
ing of the heat transfer of various surface structures, particularly for boiling buoyancy driven flows in enclosures, and nano-carrier thermal motion and
and condensing applications. Finally, use of alternatives to traditional transport. Ayyaswamy has won many awards for his research accomplish-
shell-and-tube construction, such as plate exchangers, will continue to ments, most notably, the Max Jakob Memorial Award (2014), the Heat
grow because they are more efficient than TEMA construction. Transfer Memorial Award in the Science Category (2001), the Worcester
Reed Warner Medal (2007), and the AIAA “Aerospace Professional of the
Biography: Thomas G. Lestina, vice president, engineering services, has Year” award (1997). He has also won awards for distinguished teaching,
more than 30 years of engineering project management experience. He most notably the Lindback award. Ayyaswamy has been invited three
directs HTRI’s contract and consulting services, as well as oversees times by The National Research Council of the National Academies
technical support and training services. Lestina also assists in developing Committee, Washington, DC, to serve on distinguished national panels.
and customizing training, and routinely teaches courses. He earned a BS
in mechanical engineering from Union College, Schenectady, New York,
and an MS in mechanical engineering from Rensselaer Polytechnic
Institute, Troy, NY. Prior to joining HTRI, he worked as a lead engineer for Track 11: Materials: Genetics to Structures
MPR Associates, Inc., Alexandria, Virginia. Besides being a member of SESSION 11-22-1: PLENARY SESSION
ASME, he serves on the technical committee for the ASME Performance Thursday, November 19, 8:00am–9:30am
Test Code 12.5, Single Phase Heat Exchangers. He is a licensed profes- 371F, Convention Center
sional engineer (PE) in Texas. Size Effects in Nanoscale Metallic Structures: From MD Simulation to
Strain Gradient Plasticity (IMECE2015-54230)

George Voyiadjis
Track 10: Heat Transfer and Thermal Engineering Louisiana State University
SESSION 10-44-2: ASME-AICHE MAX JACOB AWARD LECTURE
Monday, November 16, 1:15pm–2:45pm Abstract: In single-crystalline metals, the sources of size effects depend
362F, Convention Center on the sample length scale. In bulk samples, the interaction of dislocations
Modeling of a Nanoparticle in a Cylindrical Vessel Flow: Particle Shape with each other is responsible for size effects which is commonly termed
and Wall Effects forest hardening. The Taylor-like hardening models are usually incorporat-
(IMECE2015-54218) ed to capture the forest hardening which states that the strength increases
as the dislocation density increases. As an example, the fact that the
Portonovo S. Ayyaswamy nanoindentation hardness increases as the indentation depth decreases is
University of Pennsylvania justified as an increase in the density of geometrically necessary
dislocations. In the cases of small length scales, several experiments on
Abstract: Modeling studies of the motion and transport associated with a whiskers, wires, and micropillars have demonstrated that the sources of
nanoparticle in a cylindrical vessel flow are useful to the development of size effects are different from those of bulk material. In the case of
optimal design criteria in industrial engineering and for biomedical nanoindentation of nanoscale samples, it has been experimentally shown
applications. In this talk, the development of our models based on the that the hardness decreases as the density of geometrically necessary
hydrodynamic fluctuation theory and the Langevin dynamics will both be dislocations increases in the region of small indentation depths. It shows
discussed. The physics and numerical aspects of modeling will be that the size effects theory of bulk material cannot be extended to the
highlighted. The effects of two commonly employed particle shapes– indentation of nanoscale samples. First, the effect of different boundary
spherical and elliptical–and shape deformability will be displayed. Vessel conditions on the simulation of nanoindentation using Molecular Dynamics
wall effects will be explained. Some applications of our models will be (MD) are investigated. Next, the dislocation length and hardness of
demonstrated, and some other possible applications will be identified. metallic samples are studied during nanoindentation with various tip
Support: NSF-CBET-1236514, NIH R01 EB006818, NIH U01 EB016027 geometries including conical and flat indenters using MD. The obtained
results are compared to the available theoretical predictions. The large
Biography: Portonovo S. Ayyaswamy is the Asa Whitney Professor of
scale atomistic simulation is then incorporated to investigate the size
Dynamical Engineering at The University of Pennsylvania, Philadelphia. He
effects in a nanoscale single crystal Ni thin film during indentation using a
received his BE (1962) from the University of Mysore, India, his MS (1965)
conical indenter with a spherical tip. The results show that the hardness
and ME (1967) from Columbia University, New York, and PhD (1971) from
decreases as the dislocation density increases, and the forest hardening
UCLA. During 1971–1974, he was a postdoctoral scholar in the Institute of
model cannot capture the strength size effects during nanoindentation at
Geo and Planetary Physics and in the Depepartment of Energy and 37
small length scales. It is observed that the size effects is initially controlled
Kinetics at UCLA. He has been at U. Penn since 1974. Ayyaswamy has
by dislocation nucleation and source exhaustion. As the indentation depth