Verification of CFD tool for simulation of cavitating flows in hydraulic systems

Abstract

Cavitation is an undesirable phenomenon in hydraulic systems, as it causes erosion and noise. The main difficulty in cavitation prediction when using Fluent software is lack of an openly accessible tool for implementation of a freely chosen homogeneous cavitation model. In this paper the main challenge is to make such a tool, user defined function (UDF). The second challenge is to use a qualitative method in the assessment of the results of verification process. Three cavitation models are verified in Fluent 14.5: Singhal et al., Schnerr & Sauer and Zwart et al. The verification is based on the benchmark example from the Cavitation Modeling tutorial. Three methods of the algorithms verification are used: analysis of the convergence history of volume fraction, comparison of vapour volume fractions and statistical analysis of these data. The original achievements are not only the verified codes but also statistical analysis based on the computer methods of image analysis performed using two correlation coefficients: the first based on the cavitation intensity, and the second based on the changes of the cloud shape. The results of the analyses do not give any reasons to reject the UDFs. The appendix contains the analysed codes (available with the online version of this paper).