A perspective on recent developments in RANS modeling

Some recent developments in RANS modeling are reviewed under the organizing theme 'connections between theory and practice', Several cases where theory has proved useful are described: the nature of unsteady, Reynolds averaged computation is discussed; models that might be considered as spawned from realizability, or from rapid distortion theory are cited; the role of bifurcation theory in explicating aspects of second moment closure is noted; constraints devised from edge solutions are mentioned. Practical connections of such ideas range from devising the analytical form of the closure, to fixing faults that occur in widely used models. Faults include the likes of spurious energy production, insensitivity to external forces, and anomalous free-stream dependencies. In connection with unsteady RANS, remarks are made on using bridled RANS closures for detached eddy simulation.