| |
|
Highlights
- Talks from distinguished
experts:
- Tours for the labs in DLR and MPI
including the Fassberg Lab
- A city tour focusing on Göttingen's
Scientific Past
- Openning Night Barbeque Poster
Session
|
 |
Plenary
Talks
 |
| Eberhard Bodenschatz "Experiments in
Turbulence" |
| Fluid
turbulence leads to a dramatic enhancement of transport and mixing and
therefore is of great importance in a wide variety of natural and
industrial processes from cloud physics to chemical reactors. These
effects arise directly from the violent accelerations experienced by
fluid particles as they are buffeted by enormous pressure gradients
generated in incompressible turbulent flows. Despite the fundamental
importance of these issues, only recently with the advance in detector
technology (silicon strip, CMOS) it has become possible to measure the
3D particle trajectories in highly turbulent flows. Here we describe
the use of a 3D direct imaging particle tracking technique that
measures simultaneously the position, velocities, and accelerations of
many particles advected by the flow with very high temporal and spatial
resolution. We report measurements of the statistical properties of
turbulence both in space and in time when measured along the trajectory
of particles. Properties reported will include particle acceleration
and two particle dispersion. The results are compared with predictions
from Richardson (1925), Heisenberg (1948), and Batchelor (1956). In
closing we will give an overview of the G\"ottingen High Pressure
Turbulence Facility and of cloud physics experiments on Germany's
highest mountain at 2700m. |
|
 |
| Klaus Ehrenfried "A
new test facility for the study of unsteady aerodynamics and
aeroacoustics of high speed trains" |
The operation
of modern high speed trains involves many technical and fundamental
problems. Some of these are crucial for the further development of
faster and more energy efficient trains. One example is the generation
of compression waves during tunnel entry. The waves propagate at speed
of sound through the tunnel and are partly reflected at the open end.
Some part of the wave energy is emitted as sound wave to the exterior.
Both the reflected and the emitted wave can cause problems. The
reflected wave hits the incoming train in the tunnel and leads to
strong pressure fluctuations at the train. To prevent discomfort or
even injury from the passengers the wagons of high speed trains must be
pressure sealed, which leads to extra weight of the trains and thereby
higher energy consumption. Additionally the emitted waves can cause
inconvenience in the neighborhood of tunnel portals. To reduce both
effects modern tunnels are constructed with extended portals, which
have special openings to reduce the compression waves. Before such
constructions are realized extensive numerical and experimental studies
have to be performed to proof the efficiency of the design.
Recently a new test facility was build where the generation of the
compression waves can be studied using downscaled model trains. An
important parameter for the generation process is the Mach number. To
be comparable with the full scale world the Mach number in the
experiments has to match the value of the real train. This means that
the model trains have to run at the same speed as full scale high speed
trains. To achieve this the model trains are accelerated by a hydraulic
driven catapult. After the acceleration phase the models run on the
track at nearly constant speed through a model tunnel. The velocity of
the model vehicle is adjusted by the hydraulic pressure. The maximum
speed is 100 m/s. The track has a length of about 65 m, and the rail
gauge is 57.5 mm. This corresponds to a scaling of 1:25. The facility
is designed for model scales between 1:20 and 1:100. The maximum weight
of a model is 10 kg. The models are gently decelerated at the end of a
track in a long chamber which is filled with small expanded polystyrene
spheres.
Beside the topic of tunnel entry and compression waves the new moving
model facility allows the investigation of much more phenomena which
are difficult to simulate in ordinary wind tunnels. These are for
example the effect of unsteady cross wind on the stability of trains or
unsteady slip stream effects due to train passage. |
|
 |
| Adelia Sequeira
"Absorbing boundary conditions for 3D fluid-structure interaction
problems to model blood flow in compliant vessels," Get the talk here |
| Blood flow
interacts mechanically with the vessel wall, giving rise to pressure
waves propagating in arteries, which deform under the action of blood
pressure. In order to capture these phenomena, complex fluid-structure
interaction(FSI) problems must be considered, coupling physiologically
meaningful models for both the blood and the vessel wall. From the
theoretical point of view, this is extremely difficult because of the
high non-linearity of the problem and the low regularity of the
displacement of the fluid-structure interface. So far, mathematical
results have been obtained only in simplified cases. From the numerical
point of view, the use of partitioned schemes, which solve iteratively
the fluid and the structure sub-problems, supplied with suitable
transmission conditions, is difficult to handle in hemodynamic
problems, due to the large added mass effect. In this talk we introduce
some recent mathematical models of the cardiovascular system, in
particular non-Newtonian blood flow models, and comment on their
significance to yield realistic and accurate numerical results.
Simulations of the mechanical interaction between blood flow and vessel
walls will be shown. A 3D FSI model in a compliant vessel is used to
describe the pressure wave propagation. The 3D fluid is described
through a shear-thinning generalized Newtonian model and the structure
by a 3D hyperelastic model. In order to cope with the spurious
reflections due to the truncation of the computational domain, several
absorbing boundary conditions are analyzed. Firstly, a 1D hyperbolic
model that effectively captures the wave propagation nature of blood
flow in arteries is coupled with the 3D FSI model. Moreover, absorbing
boundary conditions obtained from the 1D model are imposed directly on
the outflow sections of the 3D FSI model, and numerical results
comparing the different absorbing conditions in an idealized vessel are
presented. Results in a realistic carotid bifurcation and in a
patient-specific aneurysm are also provided in order to show that the
proposed methodology can be applied to physiological
geometries. |
|
 |
| Rainer Hollerbach
"Theory of liquid metal experiments in rotating cylinders and spheres,"
Get the talk here |
The Earth's
magnetic field is produced by so-called dynamo action in its molten
iron outer core. Stars and other astrophysical objects often also have
associated magnetic fields, which can significantly influence their
structure and evolution. There is therefore considerable interest in
performing geophysically and/or astrophysically motivated laboratory
experiments involving liquid metals. In this talk I will review four
possible such experiments involving liquid metals and externally
imposed magnetic fields. Specifically, I will consider cylindrical and
spherical geometries, and mechanical and electromagnetic forcing,
yielding the four cases
- Cylindrical Geometry, Mechanical Forcing
- Cylindrical Geometry, Electromagnetic Forcing
- Spherical Geometry, Mechanical Forcing
- Spherical Geometry, Electromagnetic Forcing
I will present the relevant theory underlying each configuration, their
similarities and differences to one another, and prospects for future
experimental developments. |
|
Conference
Timetable
The conference timetable is shown below,
a copy of this can be downloaded here,
and for more details about the individual talks, please see the schedule
of talks.
|
|
|
|
|
|
| 8:00 |
|
Registration |
|
|
|
| 8:30 |
|
Welcome |
|
|
|
9:00 - 10:00
|
|
Plenary Talk
Bodenschatz |
Plenary Talk
Ehrenfried |
Plenary Talk
Sequeira |
Plenary Talk
Hollerbach |
| 10:00 - 10:20 |
|
Coffee Break |
Coffee Break |
Coffee Break |
Coffee Break |
| 10:20 - 11:20 |
|
Turbulent Transport (4) |
Aerodynamics (4) |
Bio-fluid mechanics (4) |
Geophysical flow (4) |
| 11:20 - 11:30 |
|
Break |
Break |
Break |
Break |
| 11:30 - 12:30 |
|
Applications (4) |
Hydrodynamic Stability (4) |
Multiphase flow (4) |
Transition to turbulence (4) |
| 12:30 - 13:30 |
|
Lunch |
Lunch |
Lunch |
Lunch |
| 13:30 - 14:30 |
|
Num. methods for
hydrodynamic stability (4) |
Turbulence:
particles and stratification (4) |
Turbulent flows (4) |
Closing |
| 14:30 - 14:40 |
|
Break |
Break |
Break |
|
| 14:30 - 14:40 |
|
Buoyancy & temperature driven
flows (4) |
Control (4) |
Lab Tour: |
|
| 14:40 - 15:40 |
|
Lab Tours: |
Walk to city |
Fassberg |
|
| 15:40 - 16:00 |
|
DRL and MPI |
City Tour |
|
|
| 16:00 - 16:40 |
|
|
|
|
|
| 16:40 - 17:00 |
|
|
|
|
|
| 17:00 - 17:20 |
Arrivals |
Poster Preparations |
|
|
|
| 17:20 - 18:30 |
and Registration |
Poster Presentations |
|
|
|
| 18:30 - ??:?? |
|
Poster viewing
& Barbeque Dinner |
|
Conference Dinner |
|
About the EPFDC
The European Postgraduate Fluid Dynamics Conference is an annual
conference organised and attended by doctoral students across Europe,
and across the world, with the purpose to bring together postgraduate
students working in various fields of fluid dynamics, allowing them to
show and discuss their work in an environment of their current and
future peers.
This year's conference marks its fifth run. All previous conferences,
EPFDC-2007 (Birmingham),
EPFDC-2008 (Keele), EPFDC-2009 (Nottingham), EPFDC-2010 (Paris) have shown to be a success
and have proved to be an excellent platform for students to both
present their research and network with others.
The conference provides the attendees an open-forum for giving a short
talk or a chance to display a poster. Additionally, scholars from a
broad range of fluids-related topics are invited to give plenary talks
aimed at providing students with insight into areas of current
research. Attendees are also encouraged to engage with each other and
the speakers during planned social events, such as the openning night
barbeque poster session, the lab and city tours, the conference dinner,
and coffee breaks between talks, all of which are beneficial in the
development of communication and networking skills.
The conference will be jointly hosted by the Max Planck Institute for
Dynamics and Self-organization (MPI-DS) and the German Aerospace Centre
(DLR) in Göttingen, institutions which have a long-standing tradition
in fluid dynamics. Students will not only hear plenary talks in current
aerodynamics (Prof. Dillmann, DLR) and turbulence (Prof. Bodenschatz,
MPI-DS), but they will also be able to visit lab facilities where
leading research on these topics is conducted. The research complex
that comprises the MPI-DS and the DLR has a well-equipped lecture hall
and a canteen where lunch and refreshments will be provided. It is
situated directly next to the town centre and within walking distance
to the hotels. Visits to the host's facilities will be complemented
with an official city tour highlighting the remarkable scientific
history of Göttingen. |
 |
Last modified:
06.02.2012
·
Salewski Matthew, Physik, 24239
|
|
|
