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Dynamics of Chemically Active Suspensions

Citation

Yan, Wen (2016) Dynamics of Chemically Active Suspensions. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9Z60M1V. http://resolver.caltech.edu/CaltechTHESIS:05242016-214836974

Abstract

Chemically active particles may swim by self-diffusiophoresis in a concentration gradient of chemical solutes they created themselves by patterned surface catalytic reactions. Those particles can also interact via normal diffusiophoresis in the same solute concentration field. The interaction can be attractive or repulsive. This 'field-driven' nature of the system makes its dynamics different from a thermodynamic system and is analyzed with a new simulation method. Simulations show that attractive active particles exhibit coexistence of dense and dilute regions, but it is different from a liquid-gas phase equilibrium. To explain the behavior, a continuum mechanics theory is developed based on the minimal Active Brownian Particles (ABP) model. In the continuum description, the surface force is found to be the swim stress, which can be anisotropic. The body force includes the average swim force as an internal contribution and an 'activity-gradient' force contribution. Further, behaviors of active matter at the sub-continuum scale are also analyzed. The continuum mechanics theory is shown to accurately describe the behaviors of chemically active particles. Particle clustering is explained with a linear stability analysis, and the steady state is explained with a sedimentation-like mechanical force balance.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Colloids, Active Matter, Stokesian Dynamics, Diffusiophoresis, Continuum Mechanics
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Mechanical Engineering
Thesis Availability:Withheld
Research Advisor(s):
  • Brady, John F.
Thesis Committee:
  • Brady, John F. (chair)
  • Hunt, Melany L.
  • Kochmann, Dennis M.
  • Wang, Zhen-Gang
Defense Date:24 May 2016
Non-Caltech Author Email:wenyan4work (AT) gmail.com
Record Number:CaltechTHESIS:05242016-214836974
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05242016-214836974
DOI:10.7907/Z9Z60M1V
Related URLs:
URLURL TypeDescription
http://dx.doi.org/0.1103/PhysRevLett.113.028103DOIArticle: Swim Pressure: Stress Generation in Active Matter
http://dx.doi.org/10.1039/C5SM01318FDOIArticle adapted for ch. 2: The swim force as a body force
http://dx.doi.org/10.1017/jfm.2015.621DOIArticle adapted for ch. 3: The force on a boundary in active matter
ORCID:
AuthorORCID
Yan, Wen0000-0002-9189-0840
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9743
Collection:CaltechTHESIS
Deposited By: Wen Yan
Deposited On:09 Mar 2017 22:01
Last Modified:09 Mar 2017 22:01

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