Marine physical/biological interaction

The phytoplankton lie in the lower end of the food chain and are also essentail for the photosyntheic fixation of the atmosphere carbon. While similar to any plant the phytoplankton productivity relies on the availability of light, nutrients and carbon, it has been shown that they are modulated by ocean physical processes and air-sea fluxes. One well-known scenario is the spring bloom which greatly depends on fronts in the ocean. I study the effect of the physical/biological coupling on the productivity of the phytoplankton in the ocean.

Numerical modeling of stratified wall-bounded flows

Development of DNS and LES has opened a new route to researchers to investigate environmental flows. However, these valuable methods are still limited to low-Reynolds-number flows with idealized geometries and are not suitable for engineered applications. Hence, RANS models have remained popular for industrial applications. In spite of fast calculation, RANS models suffer lack of accuracy and need to be validated with exact data. Most RANS schemes are developed based on homogeneous data and assumptions and are not suitable for modeling wall-bounded flows. In my doctoral research, I seek some novel propositions that are appropriate for simulating stably stratified wall-bounded flows using RANS schemes.

Interaction of internal waves with bottom boundary

Interaction of stratified flows with the solid bottom boundary is a main source for generation of internal waves. This interaction can lead to generation of near-inertial internal waves which appear as a prominent peak in the internal wave spectrum. In some specific occasions, if the bottom topography wavenumber is an integer coefficient of the wavenumber of incident internal wave, the interaction could lead to generation of high wavenumer internal waves which are potentially susceptible to breaking.


Near-wall turbulence

Flows occurring in the presence of solid wall are ubiquitous in nature. The existence of the solid wall introduces high anisotropy and inhomogeneity to the turbulent flow, especially close to the wall. In the so-called near-wall region, about 50% of the total velocity is obtained, while it hardly occupies almost 1% of the flow total depth. Hence, understanding the near-wall turbulence remains an obscure problem. This will be even more complicated when buoyancy forces exist due to density stratification. Such cases can be considered as the most sophisticated problems of turbulence. The aim of my research is to shed some new light on these problems through parameterizing the turbulent mixing with the recourse to dimensional and analytical reasoning verified with available highly resolved DNS data.