Non-linear turbulence models for multiphase recirculating free-surface flow over stepped spillways

Abstract

Abstract The flow over a stepped spillway is free surface, multiphase and turbulent. Moreover, a recirculation region occurs at each step of the spillway. The flow characteristic is hence complicated and difficult to predict. In previous work on stepped spillways (Chen et al. Journal of Hydraulic Engineering, ASCE, 128 (7), 683–688 and Xiangju et al. Science in China Series E: Technological Sciences, 49 (3), 674–684), only the linear turbulence model was applied which gave low accuracy. Furthermore, there are still no optimised model constants for this kind of flow. The present work therefore aims to apply the large eddy simulation (LES), the non-linear and the modified non-linear turbulence models to simulate the flow over the spillways with various slopes and step heights. It is found that the modified model is able to predict the flow close to the LES but requires less computational time by a factor of up to 4. Moreover, the modified model gives higher accuracy than the LES for the cases of the spillways with higher slopes and step heights. Keywords: non-linear turbulence modellarge eddy simulationmultiphase flowrecirculating flowturbulent flowfree-surface flowstepped spillway Acknowledgements This research work is partly supported by the Thai National Grid Centre and SUN Microsystems. The financial support from the Kasetsart University Research and Development Institute (KURDI), the Commission of Higher Education and the Thailand Research Fund (TRF) are also acknowledged.