Research on influencing factors for proper orthogonal decomposition basis functions in a hydrodynamic retarder

This paper mainly investigates the factors influencing the Proper Orthogonal Decomposition (POD) basis functions created by the method of snapshots. The factors consist of the spitting of the snapshots, the sampling frequency of snapshots and the speed of the rotor. For this purpose, both the velocity and pressure fields on the surface between dual-rotor and stator of hydrodynamic retarder working in the full-filled conditions are treated as object to study. The factors are divided into the internal and external factors and discussed separately in the paper. The energy captured by the POD basis functions are used to weight the impact caused by the factors while the error of reconstruction by energetic POD basis functions is shown to analyze the effect of different factors quantitatively. Furthermore, the features of the POD basis functions created when the factors are different are shown separately for comparison. From the analysis of the results, it can be concluded that both the spiting of snapshots database and the frequency of sampling snapshots have a significant effect on POD basis functions while the features of POD basis functions are immune to the speed of the rotor.