When we initially consider the analysis of unsteady phenomena in turbomachinery, aeroelasticity and aeroacoustics, we’re quickly confronted by the simulation cost – transient analyses by their very nature will simply take longer to run compared to steady ones. And for these types of problems, where the simulation objectives (understanding of flutter and limit cycle oscillations for example) demand a time-dependent treatment, the time steps need to be small and the physical time required can be long. Not that this isn’t challenging enough, usually, the entire machine needs to be modeled at a high level of spatial fidelity, thereby driving up the size and cost of the analysis even further. But, all is not lost– enter the Harmonic Balance method, first introduced with STAR-CCM+ 4.04 in 2009, capable of delivering at least a 10-fold reduction in your time to a solution. And, that’s not the only benefit to be had with this approach – it’s possible to mesh just a single blade passage through all the blade rows in your machine and obtain a solution which varies from blade-to-blade, capturing critical blade row interactions.