- Title Information
- Title
- Dynamics of structures in active suspensions of paramagnetic particles and applications to artificial micro-swimmers
- Name:
Personal
- Name Part
- Keaveny, Eric E.
- Role
- Role Term:
Text
- creator
- Origin Information
- Copyright Date
(keyDate="yes", encoding="w3cdtf")
- 2008
- Physical Description
- Extent
- xxi, 170 p.
- digitalOrigin
- born digital
- Note
- Thesis (Ph.D.) -- Brown University (2008)
- Name:
Personal
- Name Part
- Maxey, Martin
- Role
- Role Term:
Text
- director
- Name:
Personal
- Name Part
- Karniadakis, George
- Role
- Role Term:
Text
- reader
- Name:
Personal
- Name Part
- Powers, Thomas
- Role
- Role Term:
Text
- reader
- Name:
Corporate
- Name Part
- Brown University. Applied Mathematics
- Role
- Role Term:
Text
- sponsor
- Genre (aat)
- theses
- Abstract
- Micron-size paramagnetic particles suspended in viscous fluid will aggregate to form linear chains when subject to a uniform magnetic field. This process provides a way of changing
the rheological properties of a suspension or building structures for microfluidic devices. We present a method to efficiently and accurately quantify the magnetic interactions between these
particles. With this model and the force-coupling method, we perform simulations of both small ensembles and suspensions of thousands of paramagnetic particles subject to shear flows or rotating
applied magnetic fields and demonstrate that in these situations an accurate representation of the fluid forces is necessary to estimate chain length. The artificial micro-swimmer is a device
constructed from a flagellum-like tail of chemically linked paramagnetic beads tethered to a human red blood cell. To simulate this device, we develop an elastic coupling model that treats each
chemical link as an inextensible, flexible rod. We demonstrate that when this device is subject to a rotating applied magnetic field, the filament tail will deform into a helical shape rotating
with the field and propel the swimmer through the viscous fluid. Using a continuous elastica/resistive force model, we explore further the dependence of the swimming speed on the magnetic forces
and swimmer geometry in the low frequency limit. We then examine the interactions between two comoving swimmers and ascertain at what separation distance a far-field approximation of the
hydrodynamics is sufficient to reproduce the swimmers' dynamics. We also provide simulations of a single swimmer near a rigid surface and demonstrate that under certain conditions the presence
of a wall can enhance the swimming speed. We determine further the height dependence of the repulsion from the surface, and, in the case of the spiral swimmer, the lateral drift speed. Finally,
we consider a "squirmer" model for a swimming microorganism, appropriate for ciliary propulsion on time-scales much larger than the period of ciliary beating. We show that the "squirmer" model
within the force-coupling method framework provides an effective simulation tool for studying low volume fraction suspensions of microorganisms.
- Subject (Local)
- Topic
- active suspensions
- Subject (Local)
- Topic
- low Reynolds number swimming
- Subject (Local)
- Topic
- self-assembly
- Subject (Local)
- Topic
- multipole methods
- Subject (Local)
- Topic
- paramagnetic beads
- Subject (FAST)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/1909834")
- Topic
- Magnetorheological fluids
- Record Information
- Record Content Source (marcorg)
- RPB
- Record Creation Date
(encoding="iso8601")
- 20091218
- Language
- Language Term:
Code (ISO639-2B)
- eng
- Language Term:
Text
- English
- Identifier:
DOI
- 10.7301/Z0FN14GZ
- Access Condition:
rights statement
(href="http://rightsstatements.org/vocab/InC/1.0/")
- In Copyright
- Access Condition:
restriction on access
- Collection is open for research.
- Type of Resource (primo)
- dissertations