College of Science & Engineering
This group uses MSI resources to perform direct numerical simulations (DNS) of open channel flows with sidewalls under different Froude numbers. Open channel flow is a canonical problem in fluid mechanics, which involves two significant scenarios, i.e., wall bounded flow and free surface flow. However, when sidewalls appear as the spanwise boundaries, things become more complicated in this rectangular duct due to the so-called Prandtl’s secondary flow of second kind. On one hand, those secondary flows generated at the corner of sidewalls and the bottom are symmetrical about the diagonal and of equivalent strength. On the other hand, those secondary flows generated at the corner of sidewalls and the free surface are totally different in strength, position, and scale. Since secondary flows will substantially redistribute the momentum transfer in the bulk flow region and affect the heat transfer across the interface of two fluids, their importance is well recognized in a variety of applications such as hydraulic engineering, chemical industries, or in pulp and paper factories.
The researchers are also using MSI to perform high-fidelity numerical study on turbo-machinery. Hydropower systems use the kinetic energy of water currents to generate electrical energy. These technologies represent an extremely viable opportunity to access clean and renewable energy from rivers, waves, and tidal currents. On one hand, there is a need for a hydropower system that is capable of producing electricity from hydrokinetic energy of water flows in streams and channels that has a low environmental impact, can adjust to flow variability, and can contribute to protecting stream-banks and preventing bank erosion. On the other hand, there is a critical need to develop a new design of turbo-machinery which is friendly to the fish passing through the turbine. Fish movement in the turbo-machinery is essentially a fluid–structure interaction problem. This group uses the immersed boundary method to capture the interface of complex geometry in the simulation. The coupling between the turbine/pump and the flow field enables them to study the fish and flow environment interaction. The data from simulations will establish a physical basis for the mechanistic study of the fish injury in the turbo-machinery, and contribute to the design optimization for fish-friendly hydro machinery.
The researchers have developed a sharp interface immersed boundary method to simulate the interactions between fluid flows and deformable moving bodies. In addition, they use coupled level-set and volume-of-fluid method for capturing the complex geometry of the air/water interface. Their in-house simulation tool uses a finite difference method for spatial discretization and a second-order Runge-Kutta algorithm for time integration. High-resolution DNS as well as large-eddy simulation (LES) are adopted to resolve turbulence.
These studies use simulations of the fluid fields coupled with turbo-machinery. The simulations involve massive parallel computing and datasets with unprecedented volumes and details due to the complex hydropower machinery structure. The simulation results will establish a physical basis for optimization of the turbo-machinery.
Research by this group was featured on the MSI website in August 2018: Modeling an Air-Pollution Filtration System.