The successful application of eddy resolving simulations to most areas of a modern gas turbine aeroengine is considered. A coherent modeling framework is presented to address coupling challenges. A flow classification is also given. The extensive results presented are shown to be promising but many challenges remain. In the short term, the use of eddy resolving simulations should see greater use in Reynolds-averaged Navier–Stokes (RANS) and lower-order model calibration/development—this is starting to happen already. Ideally, in the near future, RANS, large eddy simulation (LES), and test should work in harmony. It is advocated that currently, certain costly engineering design problems can be avoided or understood using scale resolving simulations.