Determining Sources of Unsteady Energy Transfer in Time-Accurate Computational Fluid Dynamics

Abstract

With the increase in computational resources, time-accurate reacting flow, computational fluid dynamics have improved to the point where periodic, unsteady behavior associated with hydrodynamic instability and acoustic resonance can be accurately modeled. However, computational fluid dynamics solutions, like experiments, only reveal the manifestation of unstable behavior such as pressure fluctuations or vortex generation. They do not readily divulge the sources of energy transfer leading to and sustaining instabilities. Because of this, it can be arduous to correlate design decisions with overall system stability using computational fluid dynamics alone. Combining the well-established unsteady energy transport theory and a choice of viable data analysis techniques, a rigorous approach for analyzing time-accurate computational fluid dynamics solutions is established. Through this approach, the sources of driving and damping can be visualized and quantified. Thereby, the aforementioned issue is rectified and a deeper insight into the root causes of instability and its overall effect is achieved.