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The Institute of Physics of University of Latvia
(previously - Institute of Physics of Latvian Academy of Sciences) is recognized as one of the oldest
and largest worldwide centres in the field of fundamental and applied
magnetohydrodynamics (MHD) research. The employees of the Institute of
Physics (about 70 employees) carry out complex investigations of the electrodynamic,
hydrodynamic and heat/mass transfer phenomena occurring in liquid conducting
media subject to the influence of electromagnetic fields of different types,
in particular, with respect to the problems of engineering physics and liquid
metal technologies. Numerous versions of electromagnetic pumps and other
specific devices for alloys transport, stirring, pouring, conditioning have
been developed for ferrous and non-ferrous metallurgy, for the technologies
of composite material production and growth of semiconductor single crystals
and so on. The wide experience of the Institute of Physics in the field of
work with liquid metal media, the appropriate experimental equipment and
developed specific methods and procedures of measurements in molten metals
and alloys allow to perform physical and numerical simulations of different
technological processes in order to work out new original MHD methods for
controlling the hydrodynamic and heat/mass transfer characteristics of melts
in metallurgy and single crystal growth from the melt.
Crystal growth and metallurgy related research is
concentrated in the laboratory of MHD technology of IPUL. Current activities of this laboratory are
focused on complex fundamental and applied research dealt with investigations
of physical laws of a new scientific trend in applied magnetohydrodynamics –
“The use of combined electromagnetic fields for controlling the transfer
process in solidifying melts”. This trend has been set forth in the Institute of Physics of the
University of Latvia. The scientific value of this field of research is determined by a
wider use of electromagnetic methods to influence crystallization phenomena
in molten metals, alloys and semiconductor materials. Already now the
electromagnetic methods of treatment are used in a number of various
technologies related with production of specific alloys and high-quality
single crystals. The main objectives of the current research are: 1) To
investigate optimal versions of a complex influence on the hydrodynamics and
heat/mass transfer in the melt, which solidify under the impact of different
combinations and superposition of alternating and steady magnetic fields; 2)
To find out the principles of solidifying media behavior under the changed by
different types of MHD influence conditions of heat/mass transfer in the melt
and at the interface; 3) To study the relationship of hydrodynamic and
crystallization phenomena influenced by electromagnetic forces in different
methods used at the production of semiconductor single crystals and special
alloys; 4) To work out scientific and technical grounds for new MHD methods
of transfer process control in solidifying media at production of single and
polycrystalline materials.
Institute of Physics is
also one of the pioneers in the magnetic fluid research. Starting the
early 1970-ies in Institute have been performed vide spectrum of basic and
applied research: static and dynamic magnetization of subdomain particles in
ferrocolloids, ferrohydrodynamics including the colloid magnetoviscosity and
magnetorheology, thermomagnetic and magnetic solutal convection, heat and
mass transfer including the high gradient magnetic separation of
nanoparticles in ferrocolloids and that of cells in biological suspensions,
magnetic fluid technology. The Institute is relatively well equipped for
performing physical experiments as well as for preparation of ferrofluid
samples for basic and applied research. Besides the main interest to basic
phenomena, a great attention is paid also to some applied problems, firstly,
to the loudspeaker cooling and to the magnetic cell separation and magnetic
drug targeting. At the present the research is concentrated in two
departments: in the Department of Theoretic Physics and in the Laboratory of
Heat and Mass Transfer.
Current activities of the Laboratory
of Heat and Mass Transfer are directed to the development of new
temperature-sensitive ferrofluids for potential application in sensors as
well in thermal engineering (firstly, the magnetically controlled thermosiphons
and the thermomagnetic cooling of high power electric transformers). Besides
the pyromagnetic properties of complex ferrite nanoparticles in dispersions,
a great attention is paid to the transport properties of colloidal particles
in non-isothermic colloids under the effect of a magnetic field and of strong
temperature gradients. Currently, an intensive thermodiffusive transfer of
nanoparticles in hydrocarbon and water based colloids is established. The
basic research on Soret effect in ferrofluids is performed by organizing a
close collaboration with partners in Germany (Prof. S. Odenbach, Center of Applied
Microgravity, University of Bremen) and in
France (Prof. A. Bourdon and Prof. R. Perzinsky, Pierre and Marie Curie
University Paris-VI). It is planed to establish new collaborative contacts
with some teams dealing with thermodiffusion problems in ordinary
macromolecular liquids (Prof. S. Wiegand, Max Plank Institute of Polymer Research, Germany Dr. A.
Shapiro, Technical University of Denmark, Denmark).
Activities of the research group of Prof. A.
Cebers, who is leading researcher at IPUL and professor of theoretical
physics at the faculty of mathematics and physics of University of Latvia, is
concerned with pattern formation in the soft materials with
long-range electromagnetic interactions; elaboration of the
numerical algorithms for the numerical simulation of these phenomena based on
pseudospectral technique and boundary integral equation method. Particular
emphasis is made on the connection of those investigations with the
developments in the nanotechnologies where by the magnetic field induced
phase transformations is possible to create ordered structures of the
nanoobjects. Significant part of investigations is connected with the new field
of biological physics, where theoretical models for the membrane interaction
with external magnetic fields as mediated by the magnetic particles are
created. The description of field induced flattening of the membrane
fluctuations, Rayleigh instability of cylindrical membrane as induced by
magnetic field, anisotropic spontaneous curvature of membranes as mediated by
the influence of the magnetic field on the Debay screening length are carried
out in chair of theoretical physics. Now in collaboration with biologists
those investigations are focused on charged lipid behaviour in membranes
which plays significant role in the regulation of the cell activity. Another
important direction in the work carried out in chair of the theoretical
physics concerns the hydrodynamics of the interfaces between the miscible
magnetic fluids which is interesting also from the point of view of the
developing field of nanofluidics. On this subject at present moment is
working PhD student M.Igonin and this work is carried out in the
collaboration of the D.Diderot University Paris 7 where corresponding
experimental investigations are carried out. In past there were two succesful
PhD thesis defended by S. Lacis and I. Drikis concerned with the numerical
simulation of the free boundary phenomena and which were done in
cooperation with D.Diderot University Paris 7 according to the cotutelle
agreement. At present moment the agreement of the collaboration with
University Paris 6 on different topics in the magnetic colloids research exist.
Another University with which there are strong links of scientific
collaboration of the chair of the theoretical physics is University of Nice
and Sophia Antipolis. In collaboration with this university the theoretical
models of the field induced phase transformations of the magnetorheological
supensions and electrorheological fluids have been elaborated. Previous
PhD student S.Lacis had postdoc position in that university. Further impulse
on the development of the work on soft materials strongly interacting with
electromagnetic fields will give participation of head of chair of the
theoretical physics Prof.A.Cebers in programm on foams and minimal surfaces
which will be carried out by I.Newton institute of mathematical sciences
(Cambridge) in august 2002.
“Laboratory of MHD research and
training” has been established recently (2001) to provide an effective
linking between IPUL and Faculty of Physics and Mathematics of University of
Latvia. The staff members of the Laboratory are teaching undergraduate and
graduate level courses for the students of Department of Physics and also
being members of the Chair of Electrodynamics and Continuum Mechanics (EDCM),
created 1970 with the aim to prepare scientists for IPUL. Majority of the
researchers of IPUL have graduated EDCM. Since 1970 the main focus of the
research activities of EDCM has been the development of mathematical models
and corresponding software for industrial applications involving complex
interaction of EM, hydrodynamic, temperature and concentration fields
(metallurgy, crystal growth, etc.).
In 1995 IPUL in collaboration with the
chair of Electrodynamics and Continuum Mechanics created the Centre of
Computational Technology coordinating 3-year TEMPUS Project S_JEP-07923-94
“Educational Center of Computational Technology in Engineering problems
(ECCTEP)” equipped with Silicon Graphics workstations and servers (now
supplemented by high performance Linux based PC clusters) and commercial
software Fluent and Ansys. This project, with total budget 350 000 EUR,
includes 8 partners – 4 from EU, 4 from Latvia. Student and staff mobility and Intensive courses for staff members
in Computational Fluid Dynamics and Turbulence modelling (with participation
of Sheffield University and Fluent Europe Inc. leading specialists in the
field) has ensured high competence level in state-of-the-art CFD methods
which has led to several subsequent projects: International project
supported by the Volkswagen-foundation (Germany) at Latvia University in
cooperation with Hanover University (Germany) in the field of mathematical
modelling of silicon single crystal growth by floating zone method, Target
European Spallation Source, contract No ERB FMRXCT980244, fifth framework
project “Assessment of Computational Fluid Dynamics codes for Heavy Liquid
Metals”, contract No FIKW-CT-2001-80121. This project includes also one of
the partners in S_JEP-07923-94, CRS4, Italy. The created infrastructure (computers, network, library, software
licenses) is constantly being upgraded and supports many of the mentioned in
the proposal research activities. ECCTEP has also contributed to the solution
of several problem fields in Latvia – developing mathematical models for
underground gas storages (several projects in collaboration with RUHRGAS, Germany and DONG, Denmark), shallow water problems (environmental issues
of Gulf of Riga), providing the training in the use of thermography (energy
efficiency of buildings), etc.
Mathematical modeling of complex
crystal growth processes is carried out at the MHD research and training
laboratory by the research group of Dr. A. Muiznieks. The available software
and hardware as well as the high expertise of the researchers allow carrying
out of sophisticated calculations and analysis of modern industrial crystal
growth processes. Both the Floating-Zone and Czochralski crystal growth
methods are investigated. For the Floating-Zone growth of large (up to 8”)
single silicon crystals with needle aye technique a special system of mathematical
models and corresponding computing programs has been developed. This system
includes: the 3D calculation of high frequency electromagnetic field,
axisymmetric calculation of coupled thermal and electromagnetic fields to
determine the shape of the molten zone, axisymmetric and 3D calculations of
transient melt flow in the molten zone. The influence of external magnetic
fields are analyzed also. The calculation of transient dopant mass
transport is used to calculate the resistivity distribution in grown crystal,
including analysis of macroscopic and microscopic inhomogeneities. The work
was done in strong co-operation with the Institute for Electrothermal
processes of University
of Hanover, Germany and with company Wacker Siltronic, the leading company
in world in production of large (diameter up to 200 mm) silicon single
crystals for power electronics. For the modeling of Czochralski process also
a new system of mathematical models has been developed, including calculation
of static and alternating magnetic fields and their influence on melt motion.
The features of turbulence in large CZ Systems (crucible diameter up to 36”)
under the influence of magnetic fields has been investigated. This work is
done in strong co-operation with the Institute for Electrothermal processes
of Uniniversity of Hanover, Germany and with company Wacker Siltronic, the
leading company in world in production of large (diameter up to 300 mm)
silicon single crystals by Cz process for microelectronics. The group has
started to work on microscopic analysis of some aspects of the
crystallization process.
The Institute of Physics has
organised MHD conferences each third year (totally 13) form 60-ies up to
independence of Republic of Latvia. The participants of the conference were from all leading centres
of the MHD branch in USSR. The voluminous collection of
conference materials has been published. The advancement in research field of
MHD resulted in the organisation of IUTAM symposium “Liquid metal MHD” in Riga in 1989. The symposium initiated more rapid
re-orientation to collaboration with research centres of Europe. The reorganisation of the structure of
scientific research organisations caused a break in organisation of
international scientific activities up to the second half of 90-ies. The
significant turning point in Latvia was in 1998 with organisation of
international MHD conference with over than 150 specialists form Europe, Asia and America.
For almost forty years Institute of Physics is
publishing the journal Magnetohydrodynamics (previous Russian title
Magnitnaya Gidrodinamika). During that period many now classic results in the
field of magnetohydrodynamics have appeared on the pages of the journal -
alpha effect, cinematic MHD dynamo, labyrinthine structures of magnetic
liquids, thermomagnetic convection, etc. That gives strong evidence of
the role that the journal has played in the development of the field of
magnetohydrodynamics throughout the world
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