1980 - 1987: Research Fellow and Senior Research Fellow with the Department of Fluid Mechanics of the Institute of Mechanics and Biomechanics (from 1994 - Institute of Mechanics) of the Bulgarian Academy of Sciences (IM-BAS).

12/1990 - 08/1991: Senior Visiting Scientist with the Laboratory for Modelling in Mechanics, University "Pierre and Marie Curie", Paris VI.

01/1992 - 12/1992: Visiting Professor with National Institute of Meteorology, Madrid.

01/1993 - 09/1994: Visiting Professor with the Instituto Pluridisciplinar of the University Complutence of Madrid.

National Institute of Meteorology and Hydrology of the Bulgarian Academy of Sciences (NIMH-BAS). 10/1987 - 05/1990 (Associate Professor) and 05/1990 - 11/1990 (Professor) and Head of the Department of Informatics. 07/1991 - 12/1991 and 12/1995 - 05/1997: Professor of Applied Mathematics and Fluid Mechanics.

10/1994 - 11/1995: Senior Visiting Scientist with the Center for Nonlinear Phenomena and Complex Systems, of the Free University of Brussels.

6/1997 - 8/1998: Visiting Senior Scholar with the Department of Chemical Engineering of Stanford University.

Department of Mathematics of the University of Louisiana at Lafayette.
08/1998 -- 06/2001: Associate Professor. Since 07/2001: Professor. Since 11/2004: Professor of Mathematics and Adjunct Professor of Physics. Since 07/2007 SLEMCO Endowed Professor of Sciences. Since 08/2010: Graduate Coordinator.