Modeling nanoscale transport phenomena: Implications for the continuum

Transport phenomena at the nanoscale can differ from that at the continuum because the large surface area to volume ratio significantly influences material properties. While the modeling of many such transport processes have been reported in the literature, a few examples exist that integrate molecular approaches into the more typical macroscale perspective. This thesis extends the understanding of nanoscale transport governed by charge, mass and energy transfer, comparing these phenomena with the corresponding continuum behavior where applicable. For instance, molecular simulations enable us to predict the solvation structure around ions and describe the diffusion of water in salt solutions. In another case, we find that in the absence of interfacial effects, the stagnation flow produced by two opposing nanojets can be suitably described using continuum relations. We also examine heat conduction within solids of nanometer dimensions due to both the ballistic propagation of lattice vibrations in small confined dimensions and a diffusive behavior that is observed at larger length scales. Our simulations determine the length dependence of thermal conductivity for these cases as well as effects of isotope substitution in a material. We find that a temperature discontinuity at interfaces between dissimilar materials arises due to interfacial thermal resistance. We successfully incorporate these interfacial nanoscale effects into a continuum model through a modified heat conduction approach and also by a multiscale computational scheme. Finally, our efforts at integrating research with education are described through our initiative for developing and implementing a nanotechnology module for freshmen, which forms the first step of a spiral curriculum.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering Science and Mechanics

Department dc:contributor.department

Engineering Science and Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2011

Author dc:creator

• Balasubramanian, Ganesh

Chair dc:contributor.committeechair

• Puri, Ishwar K.

Committee members dc:contributor.committeemember

• Batra, Romesh C.
• Huxtable, Scott T.
• Mahajan, Roop L.
• Ragab, Saad A.

• molecular dynamics
• Nanoscale transport
• multiscale simulation

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-04252011-123452

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/27288