CFD CFD analysis CFD-DEM coupling method DOE Francis turbine Kaplan turbine Levenberg–Marquardt algorithm Monte Carlo dropout Technology: general issues anti-cavity fins approximation model artificial neural network (ANN) axial-flow pump blade slot capacity centrifugal pump coefficient of performance computational fluid dynamics (CFD) critical wall roughness deep ensemble deep neural network (DNN) design considerations double hidden layer double-channel sewage pump draft tube draft tube optimization dynamic simulation energy recovery energy systems external characteristics