Gregor Cvijetić

Finite volume implementation of the harmonic balance method for periodic non–linear flows

Harmonic Balance Method for non-linear periodic flows is presented in this paper. As- sumption of temporal periodicity can be used to convert harmonic transient equations into a set of coupled steady state equations. Solution of coupled equations yields flow fields at discrete instants of time throughout a representative harmonic period. The method uses second-order accurate, polyhedral Finite Volume Method. It is developed for a general transport equation and generalised to coupled non-linear equation sets, including incom- pressible Navier-Stokes equations and is implemented in OpenFOAM. Verification of the model is carried out by comparing the results with transient simulations. Preliminary re- sults for weakly and strongly harmonic incompressible flow around oscillating airfoil are presented.

Implementation and validation of the harmonic balance method for temporally periodic non–linear flows

An efficient method for tackling non-linear, temporally–periodic incompressible flows is presented in this paper. Assuming temporally fully periodic flow, Harmonic Balance method deploys Fourier transformation in order to formulate transient problem as a multiple quasi-steady state problems. The method is implemented in OpenFOAM and developed for a general transport equation and incompressible Navier–Stokes equations. Validation is presented on three test cases: oscillating scalar case for scalar transport validation, a flow around a 2D NACA airfoil and a 3D Onera M6 wing for turbulent incompressible Navier–Stokes validation. For all test cases Harmonic Balance results are compared to transient simulation results. Verification of the model is performed by changing the number of harmonics for all test cases.Copyright