In the following article, authors validated their CFD study by confirming a well-known phenomenon by CFD. The phenomenon is choking of a supersonic ejector when the outlet pressure of the diffuser reaches critical point.
They increased the outlet pressure to the critical point in FLUENT and argued that the ejector failed (entrainment ratio suddenly dropped). Then they said that this is the validation of their work.
Please read the attached file.
http://www.sciencedirect.com/science/article/pii/S0011916414004688