Numerical simulations for channel flow in disordered materials
by Rodriguez Milla, Berta Elizabeth, Ph.D., SYRACUSE UNIVERSITY, 2008, 149 pages; 3333585

Abstract:

Results are presented for a coarse-grained model of collective transport in disordered materials, which generically incorporates both elastic and plastic viscous couplings. This model is motivated by the observation of both switching and macroscopic hysteresis in the driven transport of flux liquids (and in charge density waves). Such effects are ruled out when flux lines are coupled elastically. This anisotropic model is more general—it describes elastic channels interacting plastically. For exact mean-field calculations, this anisotropic model has a complex phase diagram with many interesting features, including a tricritical point which separates the non-hysteretic region from the region where there is a coexistence of stuck and moving states. This thesis examines this coarse-grained model in finite dimensions in detail to determine what features of the mean-field model remain. We integrate numerically the viscoelastic equation of motion, for two-channel, and two- and three-dimensional models. Strong evidence is presented for the existence of a tricritical point at finite viscosity in three dimensions. For the two-channel, and two-dimensional cases, it is unclear whether or not there is a critical point at zero viscous coupling. The shape of the phase diagram is significantly different from the mean-field calculations (e.g., the depinning force is viscous coupling-dependent). We find that the model exhibits hysteresis, which, for the two- and three-dimensional cases, increases with increasing viscous coupling strength, while for the two-channel case it may reach a constant value at a large viscous coupling. The hysteretic behavior might remain in the thermodynamic limit for the three-dimensional case. The equation of motion displays transient chaos, but we did not find evidence of strange attractors. This, along with sensitive dependence on initial conditions, complicates the analysis and conclusions.

 
Advisor
SchoolSYRACUSE UNIVERSITY
SourceDAI/B 69-10, p. , Jan 2009
Source TypeDissertation
SubjectsCondensed matter physics
Publication Number3333585
Adobe PDF Access the complete dissertation:
 

» Find an electronic copy at your library.
  Use the link below to access a full citation record of this graduate work:
  http://gateway.proquest.com/openurl%3furl_ver=Z39.88-2004%26res_dat=xri:pqdiss%26rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation%26rft_dat=xri:pqdiss:3333585
  If your library subscribes to the ProQuest Dissertations & Theses (PQDT) database, you may be entitled to a free electronic version of this graduate work. If not, you will have the option to purchase one, and access a 24 page preview for free (if available).

About ProQuest Dissertations & Theses
With over 2.3 million records, the ProQuest Dissertations & Theses (PQDT) database is the most comprehensive collection of dissertations and theses in the world. It is the database of record for graduate research.

The database includes citations of graduate works ranging from the first U.S. dissertation, accepted in 1861, to those accepted as recently as last semester. Of the 2.3 million graduate works included in the database, ProQuest offers more than 1.9 million in full text formats. Of those, over 860,000 are available in PDF format. More than 60,000 dissertations and theses are added to the database each year.

If you have questions, please feel free to visit the ProQuest Web site - http://www.proquest.com - or call ProQuest Hotline Customer Support at 1-800-521-3042.