Earth Flows
A cross-disciplinary center at the University of Oslo for the study of
fluid processes on Earth.
Director: Professor Joseph LaCasce
Department of Geosciences, University of Oslo
Vice Director: Professor Andreas Stohl
Norwegian Institute for Air Research (NILU), Oslo
May 26, 2011
The evolution of the Earth’s surface environments, including it’s response to human
activity, is to a major extent controlled by a plethora of flow processes. Although
these processes operate on different scales in space and time, and involve a variety of
Earth materials, they can still be approached by the common conceptual framework of
fluid dynamics in complex systems. By combining the competence of researchers
with background in physics, geophysics and applied mathematics, it is our ambition to
build a fully integrated Fluid-Earth Systems focused research environment at the
highest international level, where the dynamics of the atmosphere, hydrosphere,
geosphere, and their coupling will be approached by a combination of theoretical,
numerical, experimental and field-based studies. Center for Earth Flows will provide
research of immediate relevance to resolve problems related to energy and the
environment. Establishing effective strategies for a sustainable development may in
fact depend on the success of integrated, cross-disciplinary projects such as Earth
Flows. We will pursue our research with short and effective channels from basic
research to education, industry and the public. Our students will have a unique crossdisciplinary background to pursue a career within academia, the industry or the public
sector.
a.
Introduction:
Once considered vast and unconnected, the Earth's surface environment is now seen
as finite and interconnected by a web of feedbacks, among the biota, oceans,
atmosphere, lithosphere, and cryosphere. The majority of interactions in this web are
flow processes, driven mainly by solar energy, but also by heat from the Earth's
interior. These flows are incredibly diverse, from storms in the atmosphere, to
glaciers, the oceanic thermohaline circulation, avalanches and volcanic eruptions. In
recent decades, researchers have recognized that many of these flows are intricately
coupled and that their behavior is significantly affected by feedbacks between the
systems. This flow-related connectedness has evolved into a new paradigm: Earth
Systems Science.
The paradigm is being shaped by geoscientists and colleagues from diverse
disciplines in the natural sciences. What they have in common is a scientific focus on
the evolution of mass, momentum and energy---the dynamics of flow processes.
However, few research groups possess the multidisciplinary competence to address
Earth Flows in an integrated fashion.
In the centre for Earth Flows, physicists, mathematicians and geoscientists
working at the University of Oslo and participating institutes will join forces to
study the dynamics of flows that shape the Earth's surface and its evolution, as
well as the coupling between the hydrosphere, atmosphere, geosphere and
biosphere.
We envision a process-oriented centre, employing computational and theoretical
methods, laboratory experiments and field observations. We seek a better
understanding of the flow processes in a variety of Earth systems, of how they
emerged and evolved over Earth history, and of how some respond to human
perturbations. The work will require 4D (three spatial dimensions plus time) data
acquisition and visualization, and sophisticated theoretical and modelling approaches.
We will create an environment where cross-disciplinary studies are the norm, and
where the connections between basic research and its applications are embraced.
b.
Earth flows:
We define “Earth flows” to encompass all fluid-like motion on earth. Earth flows thus
encompasses not only the winds, rivers and ocean currents, but landslides, glaciers,
magma and deformation processes occurring in the earth’s crust.
One may classify Earth flows according to Reynolds number, which measures the
relative importance of inertial and viscous forces. They can be further sub-divided
according to the number of components and/or phases present.
A glacier (lower left, Fig. 1) is a complex flow, with one phase (ice). Glaciers are the
largest reservoirs of freshwater on earth, and glacial melting is among the primary
drivers of global sea level rise. However, the melt rate is currently unknown, and this
is a leading source of uncertainty in climate projections. A large proportion of the
melting occurs at the interface between the ice and solid land. The meltwater not only
feeds the ocean, but lubricates the glacier, facilitating slip.
Ocean currents, like the Gulf Stream (lower right), are large Reynolds number, single
phase (water) flows. The currents are an integral part of the climate system,
transporting heat to high latitudes and exchanging CO2 and moisture with the
Fig. 1: Earth flows. A glacier, a tsunami and the Gulf Stream (below); geological folds, a sediment-
bearing turbidity current in the Gulf of Mexico, a volcano and Hurricane Ivan (above). A landslide is
shown in the middle.
atmosphere. They are driven primarily by the winds and by surface heating and
cooling, but fundamental questions remain about the stability of the large scale flows,
such as the thermohaline circulation. Furthermore, the role of turbulent eddies in
transporting heat and material is not fully understood.
Landslides (center) and turbidity currents (upper middle) are multiphase flows, in
which the Reynolds number can even vary in time and space. Landslides are a
significant risk to life and property, while sedimentation is an important issue in
coastal erosion. Sediment transport is important too in the formation of barrier islands
and fertile river deltas, such as the Nile. A lahar, which occurs during or soon after a
volcanic eruption, is a mixture of volcanic and rocky debris and water and can travel
up to hundreds of kilometers at speeds up to 30 m/s. A lahar buried the city of
Armero, Colombia, in 1985, killing 23,000 people.
Volcanoes and hurricanes occupy the upper right portion of the figure, having
intermediate to large Reynolds number and two or more phases. Volcanoes are a
significant geohazard, threatening life and disrupting human activity. The Laki
eruption killed a quarter of Iceland’s population in the 1780s and produced crop
failures and famine in Europe, while the Eyjafjallajökull eruption in 2010 halted
European air travel. Hurricane Katrina swept over New Orleans in 2005, killing over
1800 people; the city has yet to recover. Both phenomena have extremely complex
dynamics, and limited predictability.
c.
Dynamics of Earth Flows:
Earth flows are incredibly diverse. There are research groups, and in some cases
entire journals, devoted to the study specific ones. What links them though is their
dynamics---the physics and mathematics of flow phenomena, describing their
evolution in time. Nearly all flows obey a continuity equation, expressing
conservation of mass. They also have equations for the conservation of momentum
and energy, further constraining the motion. Magma in volcanoes, hurricanes and
granular materials are all modelled using variants of these basic equations. As such,
dynamics is as a common language among the disciplines, permitting similar
theoretical, computational and experimental approaches.
A consequence of the common dynamics is that the flows exhibit similar behaviour.
Viscous flows are often laminar. Multiphase flows are often controlled by the
dynamics at the interfaces---whether between ice and solid, as at the base of a glacier,
or between air and water, as in the atmospheric boundary layer. Flows with larger
Reynolds numbers can exhibit instability and turbulence. Rivers, oceans and the
atmosphere, with Reynolds numbers of 106 - 1010, are often turbulent. Turbulence,
which stems from the nonlinearity of the governing equations, implies the flows are
sensitive to perturbations and to initial conditions. Nevertheless, the statistics of
turbulent flows can be predictable, and this facilitates modelling. And the issue of
transport--how material is carried by flows--is common to nearly all geophysical
systems. This is true for sediment in rivers, for oil spilled in the ocean and for
radionuclides and volcanic ash in the atmosphere. Dynamics links the processes in all
these systems.
d.
Research Tasks and Methods:
Work Packages:
Given the breadth of Earth flows, it is not possible for a single group to study them
all. Our goal is to identify common themes and focus on them. Thus instead of
focusing on single well-studied flows, such as atmospheric fluid dynamics or river
flow, the goal is bring together scientists with diverse expertise to study important
processes in which coupling between different flows plays a critical role. This will
require a combination of different approaches.
WP1: Heterogeneous flows (Karen Mair; IG)
The flows in WP1 involve diverse constituents and have low Reynolds numbers.
Flows in the Earth's interior are often heterogeneous, with different solid constituents
and pore space filled with fluids or gas. We may classify the flows according to the
fraction of space occupied by one constituent (the inclusion) in another.
·
Single inclusions: Even simple geological systems with a low fraction of one
constituent in another can exhibit rich flow behaviour. To first order, such
systems can be treated as an isolated inclusion of variable shape embedded in
a matrix of different material properties, subject to internal and external loads.
Geological phenomena that can be studied in this framework include: particles
in shear zones [1-5], deformation around deforming cracks [6], folding [7, 8]
and emplacement of magma intrusions [9-11].
·
Suspensions: With an increased inclusion fraction, interactions (but not
necessarily contact) between inclusions become significant. This suspension
regime is not analytically tractable, so numerical and/or experimental
modelling is essential. However despite the complexities, effective media
theory is successful at predicting not only the overall effective viscosity but
also the development of a shape preferred orientation, observed for example in
porphyroclasts in shear zones [12].
·
Granular Material: At larger inclusion fractions, the percolation threshold can
be exceeded. Granular materials are in this category, and Earth Flow examples
include broken debris generated along earthquake faults or at the base of
rockslides [13] and the deformation of reservoir rocks [14]. Here system
spanning chains are ubiquitous phenomena and the densely packed skeleton is
continuously reconfigured during flow [15, 16]. The effective mechanical
behaviour is dominated by fracturing of grains and frictional interactions at
grain contacts leading to strongly non-linear rheological behaviour which is
largely independent of the interstitial fluid.
·
The Unknown In-Between: The mechanical behaviour of suspensions and of
granular systems is clearly distinct. However, many natural systems operate at
or near the transition between these two regimes and exhibit a spectrum of
rheological behaviour, including concomitant ductile and brittle mechanisms.
It is largely unknown how these mechanisms combine and how widely the
transition depends on microstructural characteristics such as grain size
distribution, aspect ratio or roughness. Another interesting aspect is the
behaviour of composite materials comprising several viscous phases where no
phase could be considered a host. The main focus of this work package will be
to quantify the details of the transition from suspensions to granular materials
in ductile-brittle materials. Key questions include:
1) Which parameters control where the transition happens?
2) What are the resulting effective material properties?
3) How do these systems evolve with strain?
The Earth flows that can be addressed with the proposed “Suspensions to granular
media” work package are numerous. We are currently studying folding in rock debrisbearing glaciers. Rock glaciers allow for in situ study of this mechanical instability in
viscous-brittle mixtures [17]. The effective properties of ice-rock mixtures are also
relevant for permafrost in landslides, a natural hazard that is becoming increasingly
frequent due to warming climate.
Another system to be studied is crystal bearing melts in volcanic conduits. These
appear to be suspensions of solid inclusions within a liquid. Introducing solid
inclusions into Newtonian melts in laboratory experiments results in a high relative
effective viscosity and a stress dependent non-Newtonian fluid. Effective media
schemes for suspensions, e.g. Einstein-Roscoe, fail to predict their behaviour. Several
mechanisms have been proposed to explain this including strain effects, fracturing of
crystals and shear heating. Another scenario is that the individual inclusions in a
crystal bearing melt can develop contacts and if their fraction is high enough they can
form sparse sporadic system spanning chains. Understanding crystal bearing melts is
not only of importance for volcanic systems but also for mantle convection and
formation of new continental and oceanic crust.
WP2: Porous and reactive flows (Bjorn Jamtveit; IG)
Fluid transport in and through porous rocks plays an important role in the dynamics of
the Earth’s crust at low to moderate Reynolds number, through its effects on transport,
deformation and chemical reactions. The dominating mechanism of fluid transport
depends on rock permeability, but also on the interaction between fluid and rock,
which may generate permeability by fracturing or chemical processes.
In porous and fractured rocks, transport occurs through surface film flows, laminar
and turbulent flows in pores, pore-throats, and fractures, as well as flows in larger
scale fracture or channel structures. Flow in porous and fractured media is at the heart
of e.g. the petroleum industry, carbon sequestration, pollutant transport and ground
water protection - hence, many of the central challenges that face humanity today.
Flow in porous media is therefore also a well-developed discipline, however, several
key challenges are still in need of a better understanding, such as how to address the
large span of scales involved, and how to address the complex chemical (e.g. the
dissolution or precipitation of solids) and physical (e.g. hydro-fracturing, electrostatic,
or various wetting behaviours) interactions between the porous medium and the
flowing fluid.
In tight rocks, rocks with very small permeabilities, fluid transport is diffusive. But
since diffusion is slow, even small heterogeneities, including grain boundaries and
thin fractures, may dominate the transport. Thus an understanding of fluid transport in
confined spaces and narrow channels, where effects of surface geometry, charges and
chemistry may be important, are necessary. While flow in porous media is a welldeveloped discipline, fluid flow through initially impermeable media also plays an
important role on both geological and human time scales. Most of our future fossil
energy may come from tight rocks, such as shales and mudstones, with permeabilities
in the microdarcy - nanodarcy range and sometimes less. These tight rocks contain
most of the organic material on the Earth, and tight ultramafic rocks also have
significant potential as hosts for permanent storage of CO2. However, our
understanding of the underlying processes relevant for prospecting, production and
storage in tight rocks is still largely undeveloped. It is therefore important to develop
a better understanding of the generation, retention, migration, and alteration of fluids
in such systems. Since tight rocks have initial low permeability, the flow is coupled to
deformation, fracturing, compaction and mineral chemistry in the matrix. We
therefore need to develop a better understanding of such coupled processes, with a
particular emphasis on cross-scale effects.
In reactive rocks, fluid transport is often closely related to deformation, fracturing and
chemical reactions. For example, in fracturing assisted reactive flow a fluid reacts
with the solid rock resulting in a volume change, which leads to deformation and
possibly fracturing of the rock. If the rock fractures, the fluid propagates into the
fracture, and the process continues. This coupled process has a first-order impact on
reaction rates in for example weathering, and also determines on the geometries of the
generated reaction fronts. Such effects are especially important for carbon
sequestration, for weathering of rocks, and for salt damage of building materials. This
coupling between reactions and transport depends on the microscopic (atomic-scale)
processes occurring during volume-changing reactions, which are poorly understood,
as well as on the large-scale coupling between fluid flow, surface properties, and
deformation.
This work package will focus on developing a better understanding of interfacial and
coupled processes during flow in tight, porous, fractured, and reactive rocks. Key
questions include:
1) What are the effective macroscopic flow properties of porous and fractured
media, in particular in media where pores and fractures are small (nanometer
scales).
2) What are the key parameters and processes for flow in tight rocks?
3) What are the microscopic origins of volume-changing reactions, and how are
they coupled to larger scale flow and deformation processes?
A particular challenge is the cross-scale nature of porous and reactive flows.
Improved understanding of cross-scale effects and upscaling is therefore a key
component of this work package. The behavior of complex fluids in nano-scale pores
and nano-scale surface shapes in e.g. shale fractures, may also require new
approaches spanning scales and physical processes. In particular, it requires a focus
on surface-near effects in confined geometries, where surface charge effects may be
important, and the interaction between fluid flow and surface reactions, where
turbulent effects may affect the dynamics of surface growth and interaction.
A key effect to be studied in this work package is the transition from flow in a given
porous structure, through flows that deform and react with the porous medium, to
flows that form their own permeability by the formation of fractures and highpermeability pathways.
WP3: Waves and Interfaces (Atle Jensen; MI)
Central to Earth flows with multiple phases is the dynamics of the interfaces
separating one constituent from another. An example is the air-sea interface. The
waves which occur here are a potential energy source, erode shorelines and, with
large amplitude, threaten marine activities and coastal communities. Waves also exist
on the interfaces separating layers of different density in the atmosphere and ocean,
so-called internal waves. Another important interface is that between ice and bedrock,
which is central to the melting and motion of glaciers. The dynamics of this interface
includes phase changes, fluid flow and fluid-solid interactions.
We are studying diverse interfacial phenomena, in the laboratory, with models and
theoretically. We employ simplified and “full” models (e.g Gramstad and Trulsen
2011a,b), including Large-Eddy Simulations (LES) and Direct Numerical Simulations
(DNS), with and without moving interfaces or two phase models, to study surface
waves and atmospheric boundary layer interactions. Specific issues of relevance to
Earth Flows are:

Wave-solid interactions: Coastal erosion is an example of how waves, in this
case at the ocean surface, can impact solids. Erosion is often estimated using
mean wave height, but observations suggest much destruction occurs in
extreme events, the most familiar being tsunamis. Waves also impact
structures, often detrimentally. Both surface and internal waves affect the
Arctic ice sheet, and contribute to its break-up. In addition, solids can generate
extreme waves, for instance when a meteorite or an avalanche strikes water
(Gisler et al. 2010; Sælevik et al. 2009).

Ice-solid interactions: For most glaciers and ice streams, the ice flux is
governed not by ice-internal deformation but by basal processes in the thin
interface between the ice, subglacial debris and bedrock. The most drastic
changes in glacier systems are related to these poorly understood basal
processes (Rignot and Kanagaratnam 2006; Raymond 1987; Harrison and Post
2003; Haeberli et al. 2005). We aim to study glacial dynamics via observations
and modeling.

Interfacial/wave instability: Instability, due to shear at an interface, can
produce overturning and turbulence. Such wave-breaking transfer momentum
from the atmosphere to ocean and enhance the turbulent mixing in the upper
ocean (Saetra et al. 2007). The breaking of internal waves is the primary
mixing agent in the ocean interior. We study wave breaking mechanisms in the
lab and with two phase models (e.g Jensen et al. 2003; Jensen et al. 2005;
Grue et al. 1999; Fructus et al. 2009). The main goal is to develop
parameterisations for momentum and energy transfer in coupled models, and
for mixing processes in atmosphere and ocean.

Wave transport: Waves also represent an important means for transport
material at the interface. This affects the dispersion of floating or submerged
material, such as oil or ice (e.g. Christensen and Weber, 2005; Christensen and
Terrile, 2009). We will also continue work on nonlinear wave-current
interactions (Broström et al. 2008). We aim to study wave transport via
theoretical analysis, DNS modelling, and laboratory experiments.
WP4: Turbulence and transport (Hans Pecseli, FI)
The flows in WP4 have large Reynolds numbers (in the range 103 – 1010 in typical
geophysical and engineering flows) and are turbulent. A volcano exhibits a range of
possibilities. At depth, the separation of volatiles from magma produces a
supercritical fluid capable of penetrating and fracturing rock. The volcano's eruption
column consists of hot gases and ash, ejected at speeds of hundreds of meters per
second into the atmosphere, reaching heights of several kilometers (Eckardt et al.,
2008). This column can collapse under its own weight to produce a pyroclastic flow-a fast-moving (~200 m/s), hot (1000 C) current of gas and rock that hugs the ground
and propagates away from the volcano. The shock waves generated in the plume can
also fragment rock, producing micron-sized particles. These are bourne aloft by the
prevailing winds (Prata et al., 2007). This advection is quasi-two dimensional, and as
such the particle clouds are drawn into filaments rather than mixed away (e.g.
LaCasce, 2008). This produces regions of high ash concentration (Schumann et al.,
2011), threatening aircraft.
We will focus on how material is transported by turbulent flows. There are a host of
interesting and important scientific problems associated with turbulent transport. One
can distinguish between passive tracers (which do not alter the advecting flow) and
active tracers (which do). In the atmosphere, volcanic ash is usually treated as a
passive tracer, while heat is an active one. Transport can be treated via the advection
of particles (or fluid parcels, the Lagrangian approach), or by advecting a continuous
field (the Eulerian framework). Some specific topics to be studied are as follows:
·
Heat transport: Solar heating preferentially warms the low latitudes. Heat is
then advected in the atmosphere, primarily in the extra-tropical “storm tracks”,
to high latitudes. The earth's surface is currently warming and this is causing a
latitudinal shift in the storm tracks, a phenomenon we currently study using
general circulation models (GCMs; Graff and LaCasce, 2011). We seek
simplified analytical or numerical models which could be used to diagnose
such changes, perhaps by treating storms as Lagrangian particles.
·
Moisture transport: It is likely that the most important aspect of climate
change will be its affect on the water cycle. We are interested in convection
and cloud formation, in the coagulation of water droplets in clouds and on the
effect of aerosols (another particle) on cloud formation. The latter effect in
particular must be better understood, both for climate modeling and climate
mitigation (such as in some geoengineering schemes, which seek to alter
cloud cover).
·
Particulate transport: As seen last year and now, with the volcanic eruptions on
Iceland, and with the nuclear disasters in Japan and Chernoble, it is important
to understand how particulates are transported in the atmosphere. One issue is
understanding how weak vertical motion, often misrepresented in models,
redistributes material with height. Another is inverse modeling---deducing
characteristics of the source from observed particle distributions. The latter is
a central issue for, e.g., monitoring greenhouse gas emissions.
·
Chemically reactive transport: The ozone concentrations over the North Pole
in 2011 were among the lowest recorded. The depletion was due to chemical
reactions with industrial emissions (and aided by the unusually low winter
temperatures). Having chemically reactive species adds another level of
complexity to turbulent transport. The smoothing done in Eulerian models
reduces turbulence effects, leading to biases in mixing between air masses. So
we are developing Lagrangian models, which capture reactions among
particles.
·
Biological transport: The dynamics at the sea surface occurring at scales of
kilometers and below are critically important for the distribution of nutrients
and of aquatic life. This in turn affects the fish stocks and the food chain. But
these dynamics are not well-understood and are typically misrepresented in
ocean models. The interaction between turbulent transport and biology is
every bit as complicated as with chemistry, and we are studying various
aspects (Pecseli et al., 2010; LaCasce and Mahadevan, 2006).
Integration:
The work packages reflect themes where center members have expertise and which
we judge to have wide applicability. But despite their differences, the themes are in
fact interlinked. Particle transport in turbulent flows is a central theme for WP4, but
some of the flows in WP1 are also particle-bearing. It is well-known that Lagrangian
chaos can occur in non-turbulent flows, if the latter are time-dependent or three
dimensional. So the statistical methods of WP4 could feasibly be applied in WP1.
We may classify these flows by the fraction of one constituent in the another. In
geology, we speak of the inclusion fraction. With atmospheric aerosols or water vapor,
we speak of the “packing fraction”. At low fractions, the constituent is generally
passive, in that it does not affect the flow itself. At large factions, the constituent can
fundamentally alter the flow, altering the large scale bulk deformation in geological
flows, or causing condensation and precipitation in air.
The flow in a porous media (WP2) is really the opposite---the motion of a fluid
through essentially a stationary matrix of particles. But such flows resemble the flows
in WP1 when the inclusion fraction is large. Then the particles themselves dominate
the dynamics.
Furthermore, interfacial dynamics are wave-like with weak perturbations to the
interface (WP3). But with large shear and\or finite amplitude perturbations, the
interfactial region can transition to turbulence (WP4), at which point the mixing of
material across the interface becomes important. The resulting mixture of phases in
the interfacial region, as occurs at the base of a hurricane, is a heteorogeneous flow of
the type examined in WP1. A full description of such flows thus requires input from
several if not all the work packages. Thus we expect a healthy interaction between the
work packages as well; they will not be isolated activities.
We will also encourage active exchange between the different activities. Thus the
laboratory experiments will be coupled with computational and theoretical activities,
with the ultimate goal to produce quantitative 2D, 3D and time-dependent insights
into diverse flow phenomena. Theoretical models are important in revealing the key
control parameters for various processes. Experiments where the relevant parameters
are fully controlled can be valuable to benchmark numerical models. Observations
also fit in in a natural way. For example, remote sensing allows for measuring flows
over a range of scales, allowing for validation of numerical models. And similar
technologies are used in the field as in the laboratory (e.g. particle image velocimetry,
close-range photogrammetry). So we anticipate these groups will also have an
energetic exchange of ideas.
Research methodology
The centre activities will revolve around four basic activities: computations, theory,
experiments and observations. Just as common thematic elements will link the
participants, so too will common methodology.
Observations. The members make use of a diverse range of instruments and
techniques, which can be utilized in a range of applications. Remote sensing (satellite)
data are used to velocities of glaciers and landslides (Kääb 2002), river and ocean
currents (Kääb and Prowse 2011; Isachsen et al., 2011), as well as clouds, frozen
ground and permafrost (Kääb and Vollmer 2000). Spaceborne radar interferometry
and light detection and ranging (LiDAR; Kääb 2008) are used to measure slow
ground movements, such as slope instabilities and tectonic displacements (Strozzi et
al. 2004). Freely-drifting instruments (surface buoys, subsurface floats and
stratospheric balloons) are important for characterizing particle dispersion in the
atmosphere and ocean (e.g. LaCasce, 2008, 2011; Koszalka et al., 2009) as well as
wave-induced transport. And geological field studies are an important means of
studying large, rare events and long-term, slow processes, neither of which are
otherwise easily observable at human time scales.
Laboratory experiments remain an important means of studying flow phenomena
under controlled conditions. We have three laboratories at our disposal:
·
OK Laboratory is designed for studying the geological flows discussed in
WP1 and WP2, including faults, landslides and magma intrusions. We have
implemented a range of high resolution and state-of-the-art techniques,
including e.g. Particle Image Velocities (PIV) measurements, Thermal
Imaging (IR), structured light mapping, image analysis, white light
interferometry (wli) and acoustic emission monitoring.
·
Hydrodynamics Laboratory is central to the studies proposed in WP3 and
WP4. It has 7 m and 25 m long tanks for studying waves, and two 35 m long
flow loops for studying one- and two-phase flows. Both liquid and gas phases
can be seeded with passive tracers to measure the flow field with PIV and for
dispersion studies. High resolution and high-speed cameras together with
pulsed lasers are used for measuring flow fields and turbulence. The vorticity
field, flow separation, Reynolds stresses and the components of the turbulent
kinetic energy budget can all be determined.
·
Coriolis Rotating Tank in Trondheim, administered by SINTEF. This is a 5 m
rotating tank, the second largest in the world (http://www.ntnu.no/trondheimmarine-RI/coriolis.html). The tank can be used for modeling atmospheric and
oceanic flows at the mesoscales (10-1000 km), and for studying the quasi-2D
processes discussed in WP4.
Numerical modeling. Center members simulate low Reynolds number flows in
complex fractured (WP1) and porous media (WP2), using finite element codes with
unstructured body-fitting computational meshes and hybrid techniques based on the
level-set method. The members also use idealized and full complexity earth system
models (ESMs), to study waves (WP3), currents and storms (WP4). Group members
are responsible for FLEXPART, which simulates atmospheric transport and is
currently used by 35 groups in 17 countries. We have also developed tools for inverse
modeling to infer source strengths of emissions into the atmosphere, which could be
applied equally, for instance, to oceanic emissions. And the group uses node-based
finite volume Large Eddy Simulations (LES) and spectral element Direct Numerical
Simulations (DNS) to study single- and multi-phase turbulent flows in complex
configurations (WP3,4).
Theory. An important challenge in understanding Earth flows is the coupling of small
scale processes- e.g. dissipation, chemical reactions, mixings- to large scale properties
and behaviors - e.g. effective rheological properties and characteristic flow patterns.
The group employs various theoretical approaches, for example linear theories for
studying laminar flows and linear stability analysis, to study pattern formation and the
transition to turbulence. We also employ statistical field theories, multiple-scale
analysis and dynamical systems theories to study nonlinear flows, both single-phase
and multiphase fluids. We are interested in how the diverse Earth flows are
manifestations of a few underlying physical principles, such as the conservation laws
and the breaking of symmetries. Another important challenge is unveiling more
universal or common features across Earth flows, either in a statistical sense (e.g.
distribution of large fluctuation events from turbulence to volcanic eruptions) or in a
dynamical sense (typical flow patterns when studied in terms of a characteristic
dimensionless numbers such as the Reynolds number).
e.
The Idea Exchange (TIE)
To promote fruitfull exchanges of ideas, energy and enthusiasm the centre will
organize a weekly scientific TIE (The Idea Exchange) forum --- comprising
formal talks by internal and external guests, informal brainstorming discussions
and technical workshops. In addition, the scientists involved will sit together---a
change of lifestyle for the participants, who are currently housed at five different
departments or institutes. In itself this is bound to encourage a fresh forward looking
approach. Such interactions are of course criticial for the success of such a diverse
centre.
f.
Relevance:
With its focus on natural phenomena, the Earth Flows project has relevance to many
issues important to society. But the studies will also have direct applications. Some
examples are:
·
Hydrocarbon recovery and transportation: Flows in complex heterogeneous
fractured and porous media are relevant for hydrocarbon migration, and the
work of the interface and turbulent sections will be applied to transport of
multiphase and particle laden fluids in pipelines – an application of growing
importance to the Norwegian and international oil industry.
·
CO2 sequestration: The heterogeneous and porous flow activities will provide
understanding, information and computer codes that will be applied to the
dynamics of subsurface CO2 storage reservoirs. The centre will have frequent
contact with SUCCESS, a centre at the University studying CO2
sequestration.
·
Wind energy: Turbulence in the atmospheric boundary layer is a critical issue
for wind turbines, and the WP4 activities are relevant. The research conducted
in WP4 will also be relevant to other renewable energy technologies including
ocean current and wave energy.
·
Water: Surface and subsurface flow, and the transport of nutrients and
contaminants, are themes which will be addressed in all the work packages.
The centre will maintain contacts with hydrologists at the University and at
the Norwegian Institute for Water Research (NIVA).
·
Climate change and its impacts: Changes in atmospheric heat transport, in
precipitation patterns, in glacial run-off and in the ocean circulation will be of
primary interest in WP3 and WP4.
·
Pollutant/contaminant transport: Centre members already generate forecasts
for the spreading of volcanic ash and radioactive plumes. The surface drifter
studies are relevant for the dispersion of oil spilled at the sea surface.
·
Inverse modelling: Tools for determining the source strengths of radionuclide,
ash or oil emissions are being developed by group members. The top-down
determination of greenhouse gas emissions for monitoring compliance with
post-Kyoto agreements on greenhouse gas emissions will be extremely
important in the future.
·
Geohazards: Many of the flows that we find “interesting” are also destructive.
These include landslides, volcanoes, earthquakes and lahars. Improved
knowledge of their dynamics will benefit urban planning.
To maintain its relevance, the centre will engage energetically in outreach activities
and with industry and and organizations with environmental concerns.
g.
Organization and Participants:
The center will bring together diverse researchers at the University of Oslo working
on flow-related problems. These include: 1) the Centre for Physics of Geological
Processes (PGP), working on complex flows in fractured media, in low permeability
systems and in multiphase viscous materials, 2) the Mechanics section of the
Mathematics department, studying turbulence and multiphase flows and oceanic
waves, 3) the Meteorology/Oceanography (MetOs) section in the Geosciences
department, studying atmosphere/ocean dynamics, clouds and geophysical transport,
4) the Physical Geography section in Geosciences, specializing in remote sensing,
landslides and the cryosphere and 5) the section for Plasma and Space Physics,
studying turbulence in plasmas and fluids, and biological effects.
There are, in addition, groups conducting related research at external institutes,
including the Norwegian Centre for Air Research (NILU), a leading center for
atmospheric transport, and the Ice and Ocean section of the Norwegian
Meteorological Institute (met.no), studying oceanic waves and variability.
The center will be localized at the Department of Physics at UiO and will be headed
by director Joseph LaCasce (UiO) with assistant director Andreas Stohl (NILU), and
supported by an office manager, an administrative secretary and a senior engineer for
the laboratories. The center will have a management board, consisting of heads of the
Departments and the Dean for Research (details), to discuss strategic issues, budgets
and reporting. It will also have a scientific advisory board consisting of international
scientists, to evaluate our progress and consult on future directions (details).
The centre will be lead by the University of Oslo and located on the Blindern campus.
The Norwegian Institute for Air Research (NILU) and the Norwegian Meteorological
Institutes (met.no) are also involved (details).
Full time:
Professors at UiO: Joseph LaCasce (IG, MetOS); Atle Jensen (MI, Mechanics); Bjørn
Jamtveit (IG); Andy Kaab (IG); Karen Mair (IG); Anders Malthe-Sørenssen (FI);
Dag K. Dysthe (FI); Øyvind Hammer (NHM); Håkon Austrheim (IG); John Grue
(Mechanics); Hans Pecseli (FI); Jon Egill Kristjansson (MetOs); Jan Erik Weber
(MetOs), Karsten Trulsen (Mechanics); Geir Pedersen (Mechanics).
Senior researchers: Andreas Stohl (NILU); Luiza Angheluta, (FI, PGP); Marcin
Dabrowski, (PGP); Olivier Galland (PGP); Anja Røyne (FI, PGP); Dani Schmid, (IG,
PGP).
Part time:
Francois Renard (Univ. Grenoble); Joachim Mathiesen (Univ. Copenhagen); Paul
Meakin, (Idaho Nat. Lab.); Galen Gisler (PGP); Anders Reif (FFI); Pal Erik Isachsen
(met.no); Oyvind Saetra (met.no); Goran Brostrom (met.no); Kai Christensen
(met.no); Massimo Cassiani (NILU); Sabine Eckhardt (NILU)
h.
Added value
Individually, these groups have achieved international recognition and won numerous
awards. They also have extensive research portfolios, in Norway, the EU and in the
United States. But they are by and large working independently, often on related
phenomena using similar methods. Our goal is to fuse these into a distinctive
organization---one that will function as a new department at the University.
The diversity of the group is the main asset of the proposal: by providing a
platform for interaction and collaboration of scientists with diverse, but related,
background, we expect that the center can lead to developing new paradigms and
provide novel approaches to mainstream problems in contemporary basic as well as
applied natural sciences dealing with flows dynamics.
i.
Equal opportunity, researcher training/education
and recruitment
The center will prioritize women in leading roles - Mair leads WP1 and two
members of our external board are women. Roughly 50% of our current Masters and
PhD students are women, increasing the likelihood that women will occupy more
senior positions in Norwegian universities and industry laboratories in the future. We
will also strive to promote young capable scientists to positions of responsibility
early in their careers.
The center will also have significant educational impacts. We will develop our own
master and PhD programs, based around geophysical flows. We will also place a
strong emphasis on computational studies, in collaboration with the University's
program in Computers in Science Education (CSE).
j.
National collaborations
SINTEF, FFI, met.no, University of Tromso
SUCCESS, ICE, SVALI
(Input here).
k.
International collaborations
GFD summer school/WHOI
DAMTP?
European Space Agency Climate Change Initiative
We have in addition established collaborations with world-class laboratories offering
complementary expertise and facilities to those in-house.
(Input here).
l.
Center integration
We expect that when the center ends, ongoing research will continue in a new
section in one of the departments in the University of Oslo Faculty of
Mathematics and Natural Sciences. A similar plan was adopted by the Centre
for Mathematical Applications (CMA).
References (in prep)