Comparative analysis of flow in a fluidic oscillator using large eddy simulation and unsteady Reynold-averaged Navier-Stokes analysis

초록

A fluidic oscillator with two feedback channels was numerically investigated using large eddy simulation (LES) and unsteady Reynolds-averaged Navier-Stokes (RANS) analysis. The shear stress transport model was used for turbulence closure in the RANS analysis, and the WALE model was used for the LES as a sub-grid model. The computational mesh size was determined based on the turbulent energy length scale inside the fluidic oscillator. The numerical results were validated through qualitative and quantitative comparisons with available experimental results for the flow field and frequency of the jet oscillation. The RANS analysis showed better overall agreement with the experimental data than the LES. The LES slightly under-predicted the reverse flow in the feedback channels and separation region in the mixing chamber. The results showed that the mass flow rate through a feedback channel is nearly independent of the total mass flow rate through the oscillator. The LES was able to resolve the turbulent mixing layer originating from the inlet wedge of the mixing chamber and two large streamwise vortices originating from the throat of the oscillator.

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