Unsteady Nozzle Simulation:
 

CFD++ Simulation of Symmetry-Breakdown in a Plane-Symmetric Nozzle

Conventional RANS or hybrid RANS/LES typically do not account for the unsteadiness in the larger (resolved-scale) structures at an inlet, or in regions where the mesh refines.  CFD++ has a unique second-generation hybrid RANS/LES capability, known as Large-Eddy STimulation (LEST), that automatically transfers any large-scale, statistically-represented kinetic energy into the resolved scales, according to the local mesh resolution.

The example on the right considers the breakdown of a jet flow from a plane symmetric nozzle.  Small disturbances eventually grow and cause the jet to skew completely to one side, generating large perpendicular forces.  Small disturbances at the inlet are capable of causing the initial shift to the opposite nozzle wall.
 LEST simulation of plane symmetric nozzle flow