The principal investigator will study mathematical problems regarding the existence, stability and instability, asymptotic analysis, and long-time dynamics of structural solutions of systems of partial differential equations. The study is divided into two independent projects. The first project concerns the stability properties of one-dimensional sources of reaction-diffusion systems that are temporally- and spatially-periodic traveling waves with defects. Pointwise Green function and Evans function techniques are exploited to investigate nonlinear stability and long-time dynamics of sources. The second project regards the vanishing viscosity limit problem of the incompressible Navier-Stokes equations in the presence of impermeable boundaries. Topics that will be addressed include the well-posedness of the Prandtl boundary-layer equation, the validity of asymptotic boundary-layer expansions, and fluid-structure interactions. The primary goal of these projects is to provide a mathematically rigorous investigation into these structural solutions and boundary-layer phenomena in fluid dynamics.
The mathematical research projects that will be undertaken are motivated by many scientific disciplines including oceanography, aerodynamics, fluid dynamics, and the dynamics of biological and chemical reactions. The objects of this study, namely traveling waves, boundary layers, and coherent structures, their stability properties and their dynamics are of fundamental importance in biology, engineering, and physics. The primary goal of this research is to provide mathematical understanding of the stability properties of these structural solutions and to develop analytical methods that can be of practical use in biology, engineering, physics, and manufacturing. Among many others, one particular practical use of the study of boundary layers is to provide fundamental principles that help engineers to calculate the friction drag of a ship, an airfoil, or the body of an airplane, and to help determining an efficient shape of the body in order to minimize the friction drag and to reduce turbulence. Another objective of this research is to study the effect of viscosity in fluid motion, and to mathematically justify phenomena related to boundary layers that have been observed in experiments. Results of this research will be disseminated through presentations at national and international conferences, seminars and publications in scientific journals.