Verification and Validation for Large Eddy Simulation of Cavitating Flow Around a Projectile Near the Free Surface

Abstract

Verification and validation (V&V) is a helpful tool for evaluating simulation errors, but its application in unsteady cavitating flow remains a challenging issue due to the difficulty in meeting the requirement of an asymptotic range. Hence, a new V&V approach for large eddy simulation (LES) is proposed. This approach offers a viable solution for the error estimation of simulation data that are unable to satisfy the asymptotic range. The simulation errors of cavitating flow around a projectile near the free surface are assessed using the new V&V method. The evident error values are primarily dispersed around the cavity region and free surface. The increasingly intense cavitating flow increases the error magnitudes. In addition, the modeling error magnitudes of the Dynamic Smagorinsky–Lilly model are substantially smaller than that of the Smagorinsky–Lilly model. The present V&V method can capture the decrease in the modeling errors due to model enhancements, further exhibiting its applicability in cavitating flow simulations. Moreover, the monitoring points where the simulation data are beyond the asymptotic range are primarily dispersed near the cavity region, and the number of such points grows as the cavitating flow intensifies. The simulation outcomes also suggest that the re-entrant jet and shedding cavity collapse are the chief sources of vorticity motions, which remarkably affect the simulation accuracy. The results of this study provide a valuable reference for V&V research.

Keywords

Cavitating flow / Free surface / Verification and validation / Error analyses / Asymptotic range

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