  The estimation of fluid flows inside a centrifugal pump in realtime is a
challenging task that cannot be achieved with long-established methods like CFD
due to their computational demands. We use a projection-based reduced order
model (ROM) instead. Based on this ROM, a realtime observer can be devised that
estimates the temporally and spatially resolved velocity and pressure fields
inside the pump. The entire fluid-solid domain is treated as a fluid in order
to be able to consider moving rigid bodies in the reduction method. A greedy
algorithm is introduced for finding suitable and as few measurement locations
as possible. Robust observability is ensured with an extended Kalman filter,
which is based on a time-variant observability matrix obtained from the
nonlinear velocity ROM. We present the results of the velocity and pressure
ROMs based on a unsteady Reynolds-averaged Navier-Stokes CFD simulation of a 2D
centrifugal pump, as well as the results for the extended Kalman filter.
