  The computational cost of parametric studies currently represents the major
limitation to the application of simulation-based engineering techniques in a
daily industrial environment. This work presents the first nonintrusive
implementation of the proper generalised decomposition (PGD) in OpenFOAM, for
the approximation of parametrised laminar incompressible Navier-Stokes
equations. The key feature of this approach is the seamless integration of a
reduced order model (ROM) in the framework of an industrially validated
computational fluid dynamics software. This is of special importance in an
industrial environment because in the online phase of the PGD ROM the
description of the flow for a specific set of parameters is obtained simply via
interpolation of the generalised solution, without the need of any extra
solution step. On the one hand, the spatial problems arising from the PGD
separation of the unknowns are treated using the classical solution strategies
of OpenFOAM, namely the semi-implicit method for pressure linked equations
(SIMPLE) algorithm. On the other hand, the parametric iteration is solved via a
collocation approach. The resulting ROM is applied to several benchmark tests
of laminar incompressible Navier-Stokes flows, in two and three dimensions,
with different parameters affecting the flow features. Eventually, the
capability of the proposed strategy to treat industrial problems is verified by
applying the methodology to a parametrised flow control in a realistic geometry
of interest for the automotive industry.
