This project relates to the numerical and experimental study of the
flow properties of concentrated colloidal suspensions on a nanometer
scale. A numerical model that successfully describes the behavior of
granular systems on a micrometer scale will be ex tended with
additional interactions to make it applicable to simulations of
nanosized colloids. This model is used to study systems such as (see
project description for details) plug flow, quicksand, fluidized beds,
an instability in a tube of sand, hydro -fracturing patterns, and a
granular Rayleigh-Taylor (GRT) instability. The study of the GRT
instability constitutes the major part of the applicants doctoral
thesis.
The main goal of this project is to extend the successful numerical
model by additional interactions, such as Van-der-Waal and Coulomb,
which become increasingly important as the particles attain a
nanometer size, and apply this model to open questions related to
colloidal suspensions. In conjunction with the numerical work
experiments will be performed to observe how the real system
behaves. A strong interaction between simulations and experiments is
an intrinsic quality of this project.
Relevant questions to address are how the GRT instability behaves on a
nanometer scale and what the ef fects of the new interactions will
be. Novel instabilities where the fingers disintegrate instead of
merge is a probable observation. The lack of a ordinary surface
tension calls on new theories for why the interface in the GRT
instability is curved. The existence of other instabilities known from
fluid dynamics, such as the Rayleigh instability, will also be
investigated by the numerical model.
The applicant has been invited by professor Hans J. Herrmann to spend
up to three years with his group ``Compu tational Physics of Materials
in Civil Engineering'' at the internationally renowned Eidgenössische
Technische Hochschule (ETH) in Zürich.