Akshay Anand (Nick)

In this project, we had a numerical database for propeller forces and moments as functions of freestream velocity and incidence angle. I have performed high fidelity computational fluid dynamics (CFD) simulations on propellers at different free stream conditions. Later I validated the simulation results with an experimental database obtained in ISAE SUPAERO low - Reynolds number wind tunnel (SaBRe). Thereafter, flow analysis was conducted to identify flow patterns that generate the asymmetric propeller forces and moments. The effect of different blade geometries (pitch angle) were also analyzed. More details can be found here.

The objective of the project was to compare the two sets of velocity measurements made at a different Reynolds number using different measurement techniques, PIV and LDA. The comparison had helped us to access the performance of these two optical methods to capture the transition of turbulence in oscillating flows and had given more insight into physics underlying the phenomenon of the transition of turbulence in oscillating flows.

Marine phytoplankton organisms are small (around 10 -100 microns) and live in suspension in a turbulent environment. During their evolution, they have developed adaptive strategies that allow them to optimize their acquisition of nutrients and light conditions, via motility, or through a specific form and behavior. We focus here on diatoms, planktonic microorganisms belonging to phytoplankton, lacking swimming capacities. We selected to model the non - spherical particle, elongated and thin, modeled as a particle undergoing the effect of drag. These particles were placed in a homogeneous and isotropic turbulent flow (direct numerical simulation, DNS) in which a passive scalar was also simulated. The passive scalar fields represented the nutritive salt necessary for the growth of diatoms. Numerical simulation targeted to consider the rate of the encounter between planktonic organisms and nutrients, under the effect of turbulence. We also studied the influence of the non - spherical shape of the particle on the encounter rate.

The objective of this project was to program a turbulent model in a simple case and to compare the results with the theoretical solution in the laminar case, and with experimental results for the turbulent case. As the case was simple, the effect of several parameters such as the number of grid point as well as the grid stretching near the wall was investigated.