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Charles C.S. Song, Fellow

Large Scale Computation of "Large Re-Small M" Industrial and Environmental Flows

Visualization of sheet/cloud cavity flow-showing changing vorticity field during one cycle of cloud cavity formation.

Research Group

Xiang Ying Chen, Research Associate
Jianming He, Research Associate
Xinping Long, Research Associate
Qiao Qin, Graduate Student Researcher
Fayi Zhou, University of Alberta, Edmonton, Alberta, Canada

There is no doubt that the Navier-Stokes equations accurately represent real fluid flows of Newtonian fluids, such as air and water. But complete solutions of the Navier-Stokes equations for turbulent flows at large Reynolds number and complex geometry are still not attainable with the state-of-the-art numerical techniques and computer facilities. Research objectives in this project are advancing the state-of-the-art of computational fluid dynamics and promoting its applications to industrial and environmental problems through the development of improved governing equations and boundary conditions and the development of improved modeling techniques and numerical schemes.

These researchers have developed the compressible boundary layer theory and the computational method based on the weakly compressible flow equations. This approach has been shown to be about one hundred times more efficient than a good conventional method based on the incompressible flow equations. The method has also been shown to accurately calculate highly time dependent flows that can not be computed with the incompressible flow approach. A single phase flow model is also being developed for the simulation of cavitating flows. By using a single equation of state for the liquid phase and the gas phase of water, various types of cavitating flows can be simulated without the need for the cavity closure condition, greatly simplifying the computation.

These researchers have also developed a general four-dimenaional vector approach to simulate time dependent three-dimensional flow. With this approach, it is possible to obtain a very accurate computational method for solving problems involving very rapid grid movement and deformation. A single phase approach to simulating cavitating flows has also been developed. Presently, these researchers are developing a computer program for the design of most efficient hydropower system with good cavitation characteristics, accurate computation of high-frequency oscillatory forces due to interactions between moving part and stationary part of hydraulic machinery, and direct computation of mechanical energy loss through hydraulic structures such as dropshaft and diversion chamber of urban sewer system.

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