Vorticity Indicators for Pumping Station Design

Abstract

The engineering design of water intake structures must consider air entrainment, with the classification of surface vortices being a crucial aspect. This classification, although initially qualitative, is essential for analyzing intake works using physical models. However, the use of numerical models to address this problem implies high computational costs due to the need for a detailed mesh to capture air entrainment. On the other hand, Computational Fluid Dynamics (CFD) models allow, at a relatively low computational cost, the identification of coherent vortex structures using indicators such as Lambda-2, Q-Criterion, or Helicity. This study analyzes the correlation between vortex structure indicators and the qualitative classification of surface vortices. Physical model tests were simulated for cases of vortices with and without air entrainment. To validate the results, the vortex persistence over time and the circulation parameter were considered. It was observed that for Lambda-2 = 1, stable structures over time without air entrainment were identified, while for values above 4, these correlated with an air entrainment situation. In the future, the aim will be to evaluate the validity of these detection thresholds to quantify scale effects.