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Theme 2

Theoretical Investigation of nonequilibrium gas flows

in micro / nano systems

Project DN 02/7 (2016-2019) with the National Science Fund of Bulgaria

Research area- Mathematical Sciences and Informatics;




tel. (+359 2)


Prof. DSc  St.  Stefanov -

Project leader

404 979 6463

Assoc. Prof. Dr Kiril Shterev


979 2007

kshterev at

Prof. Emil Manoach (Solid Mechanics)


979 6426

Simona Deneva (PhD student, Solid Mechanics) 105 979  6701



The main driver for the development of micro and nano technologies is the basic research both experimental and theoretical, that generates the necessary new knowledge and ideas about the physical processes occurring in Micro-Electro-Mechanical Systems (MEMS). It is known that the knowledge of classical continuum mechanics, and more generally, continuum physics is based entirely on the assumption of continuity of matter, allowing the use of mathematical models describing the relevant physical processes with systems of partial differential equations and appropriate boundary conditions providing continuity. However, shortly speaking, such knowledge and models fails to be valid and accurate for processes in micro / nano-sized areas. In such systems, the processes can be highly non-equilibrium with presence of discontinuities caused by the discrete nature of molecular flow. To adequately describe the non-equilibrium processes and phenomena in MEMS it is necessary to use more or less new approaches, methods and knowledge of kinetic theory, statistical and quantum physics in order to investigate the relationship and transition between continuum and discrete environments, as well as emerging phenomena in intermediate states. This is a relatively new scientific field in which a large number of scientists from many countries are engaged. This type of research is adopted for important and topical at the institutional level and comes as a part of the scientific priorities of the European Commission. Accordingly, they are intended as various sub-areas in the Bulgarian national strategy for research. Routes to the efficient use of resources must be identified and implemented to provide more environmentally friendly and resource-oriented technologies in the near future. European roadmap process intensification identified several measures: miniaturization, improved heat transfer and recovery of lost heat.

The main objective of the proposed project is the Bulgarian team to participate with qualitative contributions in the research of phenomena and processes in the world of micro / nano scale in the field of microfluidics, in which researchers from the Institute have achieved significant scientific results. The team of scientists from the Institute of Mechanics at BAS offering this project has internationally recognized achievements in theoretical and numerical studies of nonequilibrium gas flows and phenomena in MEMS. This is evident from the list of publications in prestigious scientific journals, presented for each participant.


Public archive:

A pressure based, iterative finite volume method is developed for calculation of compressible, viscous, heat conductive gas flows at all speeds. For more information click here.

Dynamic Meniscus Profile Method for Detertmination of the Dynamic Contact Angle in the Wilhelmy Plate Geometry is developed and availabel for use here.




Modified date:06-02-2019