  A Finite-Volume based POD-Galerkin reduced order model is developed for fluid
dynamics problems where the (time-dependent) boundary conditions are controlled
using two different boundary control strategies: the lifting function method,
whose aim is to obtain homogeneous basis functions for the reduced basis space
and the penalty method where the boundary conditions are enforced in the
reduced order model using a penalty factor. The penalty method is improved by
using an iterative solver for the determination of the penalty factor rather
than tuning the factor with a sensitivity analysis or numerical
experimentation. The boundary control methods are compared and tested for two
cases: the classical lid driven cavity benchmark problem and a Y-junction flow
case with two inlet channels and one outlet channel. The results show that the
boundaries of the reduced order model can be controlled with the boundary
control methods and the same order of accuracy is achieved for the velocity and
pressure fields. Finally, the reduced order models are 270-308 times faster
than the full order models for the lid driven cavity test case and 13-24 times
for the Y-junction test case.
