Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
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Experiments in the
Laboratory for Soft and Complex Matter Studies at NTNU:
http://folk.ntnu.no/fossumj
Active full-time researchers in our NTNU lab. 2010-11:
(exp. = experiments, sim. = simulations)
 Prof. Jon Otto Fossum
 Post.doc NN (to be hired soon)
 Ph.D. student Henrik Hemmen
 Ph.D. student Elisabeth Lindbo Hansen
 Ph.D. student Zbigniew Rozynek
 Research Technician Ole Tore Buset, (helps us in all exp. activities)
 Masterstudents?
Regular visiting scientists in our NTNU lab. 2010-11:
 Adjunct Prof. Kenneth D. Knudsen, (exp.) is full-time Senior Researcher at IFE
Main supervisor for project number 1.d), see below::
 Prof. Arne Mikkelsen
Principal contact for all projects given below:
Prof. Jon Otto Fossum, email: jon.fossum@ntnu.no, tel. 91139194, room E3-160
Realfagbygget NTNU. You may also contact the other supervisors listed, of course.
In many of the experiments that we describe below, it may be necessary to perform
synchrotron X-ray investigations either in France, Brazil, South-Korea, or Sweden, or
neutron scattering at IFE, Kjeller.
Some of the activities below are new, while some are ongoing, and in the latter cases,
the master student projects are continuations of these ongoing activities.
The projects we offer have ”a common denominator” and a common basic question:
What kind of relations are there between physics and structures on the nano-scale, and
macroscopic and “global behaviors” on the human scale?
It is in this context that we for example study self-organization of nano-particles:
Think of how to make “something smart” from nano-particles, “something” which is so
large that you can hold it in your hand. Such an object contains about 1020 nanoparticles (Avogadro’s number). Even if you use as little as 1 millisecond in order to move
a nano-particle into its planned place in a pre-designed structure, one particle by one
particle, it will take about 300 million years to organize the 1020 particles the way you
want. This means that self-organization of nano-particles is the only practical way to do
this, and that basic studies of self-organization of particles is a “hot topic” in science.
See also the following popular science presentations and other news from the lab:
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University of Amsterdam, Netherlands: News and Agenda: Clay soil landslides cause greater damage after minor
rainfall, November 11 2009
European Space Agency (ESA) 2009 Meet the teams 2009: Complex
Norwegian Space Centre, November 11th 2009: Spinnville studentmuligheter
Forskning.no April 13th 2009: Leire i fritt fall
European Space Agency (ESA), January 12th 2009: Four student teams selected to fly their theses!
Norwegian Space Centre, January 13th 2009: Norwegian students become weightless
Forskning.no April 6th 2007: Nanoleire demper støt
Research Council of Norway NANOMAT news April 2007: Norske leireforskere i teten
Research Council of Norway NANOMAT Newsletter May 2007: Fra komplekse fenomener i leire til nanoteknologi
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
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We need more master-students, and we offer the following projects 2010-11.
Note that we may hire students for a 1 month summer-job (for each student)
during summer of 2010, as a “jump-start” to the project of the fall semester 2010.
The projects that we offer, are outlined in the following pages.
They are all experimental physics projects.
List of contents:
1. Nano-science 1:
Spontaneous self-organization from nano-particles: Nematic phases:
1. a) Drying of droplets with suspended nanoparticles
1. b) Liquid crystalline phases and self-organization
1. c) Temperature dependent ordering in synthetic clay liquid crystals
– design of an experiment using in-house equipment and experimental work at world class synchrotron facilities
1. d) Optical studies of field induced order-disorder transitions
2. Nano-science 2:
”Guided” self-organization from nano-particles:
2. a) Complex nanowire pattern assembly via external electric field
2. b) Dual-field induced self-organization from clay particles: X-Ray studies
2. c) Self-organization from clay particles in volatile state supported by membrane
vibration: SAXS/WAXS and electron microscope studies
3. Petroleum related physics, environmental physics, nano science:
Studies of fluid transport in nano-structures:
3. a) Fluid-transport in nanoporous materials
4. Geophysics, petroleum related physics, environmental physics:
Pattern-formation in soft materials:
4. a) Characterization of the roughness of fractures in soft transparent gels
4. b) Avalanches in clays
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
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Project descriptions (supervisors in parenthesis):
1.a) Drying of droplets with suspended nanoparticles
(H. Hemmen, E. Lindbo Hansen, J.O. Fossum)
Water droplets containing disc-shaped clay nanoparticles: The effectst o fparicle
concentration, ordering and other parameters on the resulting patterns after drying.
This project focuses on patterns formed by drying of droplets containing disk-shaped
clay nanoparticles. Preliminary experiments performed by us have shown that the
resulting patterns depend strongly on the type of ordering present in the droplet before
drying: If the initial concentration of particles is high, and in particluar if the particles have
orientational order, an extended fractal network is produced (Fig 1a); If the initial
concentration is low, and there is no orientational order, the coffee stain effect [1] can be
seen (Fig 1b).
A more thourough study
of this phenomenon, with
varying
concentration,
droplet size, drying rate
etc. is needed.
We have plans to study
these samples using a
range of experimental
a)
techniques, e.g. optical
microscope, small and
wide
angle
x-ray
diffraction, SEM/TEM and
AFM. It is also interesting
to study the ordering and
transport of particles
during
the
drying
process, and also using
other types and shapes
of particles.
b)
This
project
has
Figure 1. Our own preliminary observations of patterns formed after
drying. Right image is a close up.a) High particle concentration and
relevance for degined
orientational order before drying. b) Low particle concentration and
nanostructerd thin film
isotropic order before drying.
paterning.
References:
[1] Capillary flow as the cause of ring stains from dried liquid drops, R. D.
Deegan et al., Nature 386 (1997).
http://www.complexphysics.org
Fig 2: From [3].
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
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1.b) Liquid crystalline phases and self-organization
(E. Lindbo Hansen, K.D. Knudsen-IFE, J.O. Fossum)
Liquid crystalline phases of disc-shaped nanoparticles in water: the ordering effects of
walls, boundaries and bubbles.
This project focuses on the liquid crystalline order
that our group has shown develops in initially
isotropic aqueous suspensions of disc-shaped
sodium-fluorohectorite clay nanoparticles in the
gravitational field [1,2]. The master student who
chooses this project will get to travel to synchrotron
sources in either France, Brazil or South-Korea and
experience how x-ray scattering techniques apply to
studies on soft and complex matter. Neutron
experiments at IFE, KJeller can also bee
foreseen.The main aim of the proposed project is to
further investigate the effects of container walls,
Fig 3: From [4].
suspension-air interfaces and heating induced
bubbles on the nematic order of nanosized clay platelets suspended in water. As
illustrated in Fig 3 to the left, X-rays scattered off anisotropic samples will show
anisotropic scattering patterns. It is also possible to extract quantitative measures of the
degree of order from such diffractograms, by calculating
values for the so-called nematic order parameter S2 [3].
Another way to investigate nematically ordered samples, is to
observe the samples between crossed linear polarizers.
Isotropic samples will allow no light to emerge from between
a crossed polarizers setup, and the field of view of a camera
observing the setup will thus be dark. Nematically ordered,
anisotropic samples on the other hand will change the
polarization state of the incoming light so that some light will
be transmitted from a crossed polarizers setup. A camera can
record the amount of light transmitted, and this can be related
to the degree of ordering in the sample. As a master student on this project, you will
become familiar with investigations of ordering through both such birefringence
observations, and through in-house and synchrotron based x-ray scattering experiments.
References:
[1] Orientational order in gravity dispersed clay colloids: A synchrotron x-ray scattering study of Na
fluorohectorite suspensions, E. DiMasi, J. O. Fossum, T. Gog, and C. Venkataraman, Phys.
Rev. E 64, 061704 (2001).
[2] Phase diagram of polydisperse Na-fluorohectorite-water suspensions: A synchrotron small angle x-ray
scattering study, D. M. Fonseca, Y. Méheust, J. O. Fossum, K. D. Knudsen and K. P. S. Parmar, Phys.
Rev. E 79, 021402 (2009).
[3] Inferring orientation distributions in anisotropic powders of nano-layered crystallites from a single twodimensional WAXS image, Y. Méheust, K. D. Knudsen and J. O. Fossum, J. Appl. Cryst. 39, 661 (2006).
[4] Colloidal Dispersion of Clay Nanoplatelets: Optical birefringence and x-ray scattering studies of nematic
phases, E. L. Hansen, Master’s thesis, NTNU (2008).
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
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1.c) Temperature dependent ordering in synthetic clay liquid crystals – design of
an experiment using in-house equipment and experimental work at world class
synchrotron facilities.
(H. Hemmen, E. Lindbo Hansen, J.O. Fossum, K.D. Knudsen-IFE)
This project should be interesting both for the engineering-minded and the scientificminded master student. If you choose this project you will have to design, from scratch,
(or redesign an existing) sample cell that can quickly change temperatures in the range
from ~0 to ~95 C while at the same time being small enough to fit in our X-ray sample
chamber and furthermore be transparent to X-rays. Our group has an in-house X-ray
scattering apparatus that will be to your disposal during the testing of your sample cell.
After completing the sample holder, you will be able to use it for real-life research. We
have previously done experiments at a synchrotron in Campinas, Brazil, that indicate
that nematic order is induced around air-bubbles formed by temperature-increase in
samples containing clay nano-particles in water-salt solution [1]. Temperature-induced
nematic order of nanoparticles can be a cheap and successful way of creating future
nanotechnology materials. Your project, after completion of the sample cell, will do
experiments that increase the fundamental understanding of the physics of this subject.
At NTNU, we have a highly competent
mechanical workshop that will help in
creation of the sample cell. After testing
of the sample cell at our low-flux inhouse X-ray scattering machine, a trip to
a synchrotron will enable you to do high
quality scientific experiments at a world
class scientific facility. In synchrotrons,
electrons are accelerated in circular
paths at near-light-speed velocities [2].
This results in extremely high flux X-ray
emission (remember that all charged
om [4].
particles emit EM-radiation when
accelerated). Our group regularly does experiments at synchrotron facilities in France,
Brazil, South Korea and Sweden. The ESRF synchrotron ring in Grenoble, France
(where you might go) is arguably the best experimental research facility in the world for
studies in research fields as diverse as crystallography, protein structure determination,
material science, soft condensed matter studies, X-ray imaging, X-ray spectroscopy etc.
The ESRF storage ring is shown on the picture above [3].
Doing experiments of course also means doing data analysis. In addition to the data you
will get from the experiments with your sample cell, we have a collection of data from
previous synchrotron experiments. During the project you will be taught how to study
and analyze X-ray diffraction data, and extract meaningful information from complex twodimensional diffractograms.
The master student who chooses this project will have the opportunity to do synchrotron
experiments at an international research facility.
References:
[1] SAXS study of the positional order in a colloidal solution of fluorohectorite clay at different temperatures
,D.d.M. Fonseca, Y. Méheust, J.O. Fossum, K.D. Knudsen,The International Conference on Small Angle
Scattering, Kyoto, (July 2006).
[2] Neutron and synchrotron radiation for condensed matter studies. J. Baruchel, J.L. Hodeau, M.S.
Lehmann, J.R. Regnard and C. Schlenker. Springer Verlag, (1993).
[3] The European Synchrotron Radiation Facility webpage. www.esrf.eu
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
6
1.d) Optical studies of field induced order-disorder transitions
(A. Mikkelsen, E. Lindbo Hansen, J.O. Fossum)
Optical studies on field induced order-disorder transitions: the effects of electric,
magnetic and mechanical fields on anisotropic colloidal particles.
This project is focused on the reponse of anisotropic, colloidal particles to external fields.
The applied fields can be electric, magnetic or mechanical in nature and the response
will be studied optically by birefringence observations with laser and white light, by light
scattering studies, and possibly also with x-rays. Due to their anisotropy, nanoscaled
platelets of synthetic clays suspended in water or oil will orient in response to applied
fields, and such oriented systems will display a special kind of optical property known as
birefringence. If such samples are placed between crossed polarizers, the light that
reaches a camera observing the samples will be a direct result of the degree of
anisotropy. Samples that are ordered will cause light to be transmitted towards the
observer whereas isotropic samples will not affect the polarization of light, and the field
of view for an observer will thus be dark.
As a master student on this project, you will be given the opportunity to study both
isotropic suspensions and nematically ordered samples [1] of plateshaped clay
nanoparticles by several experimental methods. Optical birefrigence in laser and white
light will be studied on both nematic samples, and on initially isotropic samples where
short electric pulses [2] or flows will cause a temporary ordering that decays once the
fields are switched off (Fig. 5). The decay is caused by the rotational Brownian diffusion,
which promotes a random ordering of the nanoplatelets. You will also be able to study
order-disorder transitions induced by flows via a static light scattering cell on an
instrument known as a rheometer, and
you may also be given the opportunity
of performing dynamic light scattering
experiments. The latter will primarily
be used to study diffusion and particle
or aggregate sizes, whereas the static
scattering gives information on
structure and order.
Fig 5: From [2]. Electric induced order
studied by laser birefrigence.
References:
[1] Orientational order in gravity dispersed clay colloids: A synchrotron x-ray scattering study of Na
fluorohectorite suspensions, E. DiMasi, J. O. Fossum, T. Gog, and C. Venkataraman, Phys. Rev. E 64,
061704 (2001).
[2] Viscosity and transient electric birefringence study of clay colloidal aggregation, A. Bakk, J. O.
Fossum, G. J. da Silva, H. M. Adland, A. Mikkelsen, and A. Elgsaeter, Phys. Rev. E 65, 021407 (2002).
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
7
2.a) Complex nanowire pattern assembly via external electric field
(Z. Rozynek, J.O. Fossum)
Nanospheres, nanodiscs, nanowires, nanotubes and nanorods have recently been
extensively explored due to their unique properties and the capabilities to bind chemical,
physical and biological entities of interest.
Nanowires are one type of small entities with a large aspect ratio. The geometrical
shape and the multifunctionalities realized in multicomponent nanowires allow tuning of
their physical, chemical, and electrical properties.
Nanowires often need to be transported and assembled in suspension in order to exploit
and capture their unique properties. To date, the properties of simple nanowire-based
devices have been determined using nanowires deposited on the surface of a substrate
either at random or else by directed assembly controlled by flowing fluids or electric
fields. These latter approaches represent a significant advance over random assembly,
yet remain limited in that the end-to-end registry and three-dimensional (3D) orientation
of nanowires are not controlled, thus precluding the rational assembly of more complex
architectures with interesting and potentially useful functional properties. Nonuniform
electric fields have been used to manipulate dielectric particles that are suspended in
liquid media. Complex nanowires pattern can be got via the application of external
electric field, which is shown in figure1.
a
b
Fig.1 (a) E-field structuring in a quadrupole with connected pairs of electrodes (b) Electric field and its
gradient are both along the radical direction. Nanowires aligned chained and attached to the inner electrode.
a
b
Fig.2 E-field induced structuring in a 3-pair electrode system. E-field applied vertically (a) and horizontally (b)
References
1. Parmar, K. P. S.; Méheust, Y.; Schjelderupsen, B. and Fossum, J. O. Langmuir 2008, 24, 1814-1822.
2. Fan, D.L.; Zhu, F.Q.; Cammarata, R.C., et al. Appl. Phys. Lett. 2004, 85 (18), 4175-4177.
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
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2.b) Dual-field induced self-organization from clay particles: X-Ray studies.
(Z. Rozynek, K.D. Knudsen-IFE, J.O. Fossum)
This project gives the opportunity to become familiar with X-ray scattering techniques
such as: small/wide angle x-ray scattering (SAXS/WAXS). You will be taught both how
to perform the in-house SAXS/WAXS experiments (figure 1) and analyze x-ray
diffractograms. You will be also involved in a sample cell design. The master student
who chooses this project will have the opportunity to do synchrotron experiments at an
international research facility.
Fig.1. SAXS/WAXS in-house equipment
Electrorheological
(ER)
fluids
and
magnetorheological (MR)
suspensions
show
dramatic and reversible
rheological changes in
applied electric or magnetic
fields, which may induce
change
from
viscous
liquids
to
visco-plastic
solids in the order of
milliseconds/seconds
in
such suspensions - follow
this link to see a movie: !!!
http://www.nt.ntnu.no/users/rozynek/Movie1.wmv.
The dramatic rheological changes are closely related to changes in microstructure. In
zero external field (first 3 seconds of the movie), the microstructure is isotropic, whereas
upon application of external field (for example 500V/mm), the particles aggregate into
columnar structures [1,2].
So far our group has been focusing on one-field and one-directional induced selfassembly (either electric or magnetic field) as it is show in figures 2 and 3 below.
Fig.2. Two copper electrodes
and the liquid sample filling
in 1mm gap (left).
Fig.3. Particles are forming
chains along the electric field
(right).
This time we would like to focus on so called two-field induced assembly using either:
- two (or even more) electric fields perpendicular (or in other configuration) to each other,
- or/and combining electric and magnetic fields together
Ad.1. By alternating these electric fields, the orientation order can possibly be improved,
hence electrorheological effect improves. New phenomena are expected to emerge!!!
Ad.2. The sample will exhibit dual responsive properties under external magnetic and
electric fields, so that the rheological effect can be enhanced!!!
References:
[1] http://en.wikipedia.org/wiki/Magnetorheological_fluid
[2] Wang B, Z. M., Rozynek Z and Fossum J O "Electrorheological properties of organically modified
nanolayered laponite: Influence of intercalation, adsorption and wettability." J. Mat. Chem (2009)
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
2.c)
Self-organization from clay particles in volatile state:
electron microscope studies.
(Z. Rozynek, K.D. Knudsen-IFE, J.O. Fossum)
9
SAXS/WAXS and
This project gives the opportunity to become familiar with X-ray scattering techniques
such as: small/wide angle x-ray scattering (SAXS/WAXS) and scanning electron
microscopy (SEM). You will be taught both how to perform the in-house SAXS/WAXS
experiments, analyze x-ray diffractograms and operate the SEM. You will be also
involved in a sample cell design.
Electrorheological fluids (ERFs) are complex liquids that become very viscous, in an
applied electric field. The transition from liquid into a solid-like state indicates that there
is an internal ordering of the ER-constituents, which leads to dramatic changes in the
rheological properties. Application of an electric field induces polarization of the
suspended dielectric particles and a chain-like structure can be formed along the electric
field direction [1]. The most common ERFs are suspensions of 1- to 100-μm polarizable
particles at volume fractions of 0.05-0.50 dispersed in an inert insulting liquid. For an
electric field E of ~ 50-5000 V/mm the particles form chains that span the gap between
the field-generating electrodes [2]. By following this link you can see the chain formation
of clay particles suspended in silicon oil as an example of an ERF:
http://zbigniewrozynek.republika.pl/movie1.wmv . In zero external field (first 3 seconds of
the movie), the microstructure is isotropic, whereas upon application of external field (for
example 500V/mm), the particles aggregate into columnar structures [3,4].
So far many researchers have been focused on that type of self-assembly described
above. The recipe for making ERF is very simple and what one needs to do is to choose
particles with high dielectric constant (such that an external electric field can induce the
electric dipole in the particle) and immerse is in the non-polar and non-conducting
matrix, for example a silicone oil / vegetable oil.
What if we this time do something completely different and not use any liquid medium,
but we let the particles to self-assembly in the air/gas ?!
Yes, it is possible, see figures below.
a)
Fig.1. Two copper electrodes
with the gap of 1mm gap.
Particles suspended in the
silicone oil a) and the selfassembly that took place in
air only b).
This is a very new direction in our research activities.
Why not to join our group and make fascinating research ?
References:
[1] Tao R and Sun J M 1991Phys. Rev. Lett. 67 398-401
[2] Fossum J O, Meheust Y, Parmar K P S, Knudsen K D, Måløy K J and Fonseca D M 2006 Europhys. Lett.
74 438-444
[3] Wang B, Z. M., Rozynek Z and Fossum J O (2009). "Electrorheological properties of organically modified
nanolayered laponite: influance of intercalation, adsorption and wettability." J. Mat. Chem
[4] http://en.wikipedia.org/wiki/Magnetorheological_fluid
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
10
3.a) Fluid-transport in nanoporous materials
(H. Hemmen, J.O. Fossum)
This project is part of and a continuation of an international collaboration involving the
researchers in Brazil, in France and in South-Korea. The project deals with experimental
studies of nanoporous media, and fluid transport/diffusion in such systems. This physics
may have relevance for membrane technology, and for control of polluting agents in for
example clay based soils. The latter application is relevant for sub-sea oil reservoirs, as
well as for containment and storage of radioactive waste.
Most porous materials that surround us, absorb water, either due to direct contact with
liquid water, or from water vapor in the surrounding air that condenses in small pores.
The water may often be modeled as capillary flow: The water wets the porous material
and is “pulled in” (blotting paper effect). This gives a water front that progresses as the
square root of the time. But if the material has pores with nanometer size (1 water
molecule is about 0.2 nm), the observed dynamics is often different from this, and there
is today no good understanding of this so-called anomalous water transport.
Small-Angle-X-ray-Scattering (SAXS) studies of water transport in a nanoporous clay
material has been studied by us recently, and the project will continue such studies. The
following pictures show examples of 2-dimensional SAXS diffractograms form our
studies in our home-lab. at NTNU. Such diffractograms give direct information about the
water content in different pore sizes in nanoporous materials.
We also want to extend our studies beyond clay based nanoporous systems, and
include other nanoporous materials, such as zeolites or paper (the blotting paper effect
studied by X-rays). The project may include work at the Federal University of
Pernambuco in Recife, Brazil, for NMR studies [1].
Reference:
[1] Fluid imbibition in paper fibers: Precursor front, Eduardo N. de Azevedo, Lars R. Alme, M. Engelsberg,
Jon Otto Fossum, and Paul Dommersnes, Phys.Rev.E 78, 066317 (2008)
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
11
4.a) Characterization of the roughness of fractures in soft transparent gels
(H. Hemmen, J. O. Fossum)
This project focuses on experimental determination of the roughness of fractures in gels,
in particular gels prepared by dispersing synthetic clay nanoparticles (Laponite) in deionized water. This topic has been the subject for several previous projects in our
group[1-3], and as a result of that records of previous experimental preparations,
experimental data and reference literature are easily available to any student who
chooses this project (you will have a head start).
The characterization of fracture-roughness by using fractals has been a hot topic for a
long time now. Experiments have shown that that when one considers the statistical
variations of the fracture surfaces, fractures in
systems as different as plaster, steel or wood all
have the same roughness [4]. The fractal study of
nature is in itself a very useful tool, as master
students working this project quickly will find out. In
fact when one tries to extract universality from
complex systems, one of the main obstacles is
finding the right level of description. This is illustrated
by the figure on the left [2]: The fracture surface on
top of a clay-water gel is indeed complex, but by
removing redundant information, we can describe the
surface’s roughness by a single fractal variable  .
om [4].
This project will be challenging (and therefore also rewarding) in several ways. It will
involve reading up on previous work, i.e. both experiments done in our group and
experiments available in international journals. It will further involve setting up and
improving our setup for controlled creation of fracture surfaces in gels, as well as
performing experiments and doing data analysis. Because this is a project that is already
quite mature, it is not unlikely that the work may lead to submission of a manuscript to an
international peer-review journal before completion of the thesis work.
The master student who chooses this project will have the opportunity to travel to Brazil
to do MRI experiments in a collaborating group at the federal university of Pernambuco.
References:
[1] Experimental Research on Fractures in Gels. Knut Magnus. Master degree thesis, NTNU Department of
Physics, June 2008
[2] Experimental Studies of Nanostructured Clay Gels. Henrik Hemmen. Master degree thesis, NTNU
Department of Physics, June 2008
[3] An Experimental Study of Fractures in Gels. Christian A. Nielsen. Master degree thesis, NTNU
Department of Physics, July 2007
[4] Scaling properties of cracks. E. Bouchaud. J. Phys.: Condens. Matter, 9. (1997).
http://www.complexphysics.org
Laboratory for Soft and Complex Matter Studies-NTNU Jon Otto Fossum (http://folk.ntnu.no/fossumj)
12
4.b) Avalanches in clays
(J.O. Fossum, H. Hemmen)
Different mechanisms for the onset and development of landslides have been reported.
However, the extreme instability (‘quickness’) of clayey soils in particular remains poorly
understood. Quickclay has caused many deadly landslides in Canada, Russia, Alaska,
Norway and Sweden. The occurrence of quickclay landslides is usually attributed to
variations in water content and/or external perturbation of the soil. As merely one
example of the latter, the infamous Rissa slide (movies are available from the Norwegian
geotechnical service) was caused by small excavation works at a nearby farm.
So far [1], our group has investigated this extreme sensitivity by studying the flow
behaviour of quickclay with different water contents in a rheometer. The sample used
was a quickclay collected from 10m depth at Tiller, Trondheim which is similar in
composition to quickclays that may be collected from other regions in the world. Our
experiments
Fig. 1: Laboratory laboratory
landslides: Picture of (performed in Amsterdam) on
the final stage of the the Tiller natural quicklay
slides: in the four samples reveal a spectacular
lines from left to right liquefaction of the material
the concentration of under flow that explains the
quickclay in water instability.
increases [1].
Laboratory
landslide
experiments in addition show
that, contrary to what is
expected, higher water content does not lead to more unstable soils. For high clay
content, the liquefaction occurs in a very thin layer of the material, the rest of the clay
moving as a solid block; this explains the large distances over which quickclay landslides
travel. We have reproduced the flow behaviour of the natural samples mixing different
clays, water and salt, which has allowed us to assess the impact on the quickness of the
different constituents of the clay.
In order to investigate such avalanches further, we want one master student to setup
and use the following type of tilted plane experiment in our lab [2]:
Fig. 2: Left: Tilted plsne experiment for studies of avalanches [2]. Right: Avalanches in systems
of sand and glass beads repesectiveøy sturdied using the experimental tilted plane setup to the
left [2].
References:
[1]Quick Clay and Landslides of Clayey Soils, A. Khaldoun, P.Moller, A. Fall, G. Wegdam, B. de Leuw, Y.
Meheust, J.O. Fossum, D. Bonn, Phys. Rev. Lett. 103, 188301 (2009)
[2] Avalanche dynamics on a rough inclined plane, T. Börzsönyi, T.C. Halsey, R. E. Ecke, Phys. Rev. E 78,
011306 (2008)
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