CD-adapco is the world's largest independent CFD focused provider of engineering simulation software, support and services. We have over 30 years of experience in delivering industrial strength engineering simulation.
Large-eddy simulation has been performed for a two-valve, four-stroke-cycle piston engine through 70 consecutive motored cycles, and proper orthogonal decomposition (POD) has been used to analyze the complex in-cylinder turbulent flow. Convergence of POD modes has been quantified, several POD variants have been explored, and sensitivity of results to using different subsets of engine cycles has been determined. In general, it has been found that conclusions that were drawn earlier from POD analysis of a simplified piston-cylinder assembly carry over to the much more complex flow in a real four-stroke-cycle engine. The utility of phase-invariant POD in analyzing cycle-to-cycle variations and in-cylinder flow dynamics is demonstrated, and it is shown that crank-angle intervals as large as 30° between samples may be sufficient to capture key large-scale in-cylinder flow dynamics.