A more detailed and realistic centrifugal pump model, namely a first order model with nonlinear algebraic constraint equations as described in (German language) Geiger G. (1985), Technische Fehlerdiagnose mittels Parameterschtzung und Fehlerklassifikation am Beispiel einer elektrisch angetriebnen Kreiselpumpe, VDI Verlag, Dsseldorf, Germany.
Note, this pump model is not thoroughly tested yet and of an experimental character at the time.