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 75 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. 

“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.