Reynolds stress model (RSM)
The Reynold's stress model (RSM) is a higher level, elaborate turbulence model. It is usually called a Second Order Closure. This modelling approach originates from the work by [Launder (1975)]. In RSM, the eddy viscosity approach has been discarded and the Reynolds stresses are directl computed. The exact Reynolds stress transport equation accounts for the directional effects of the Reynolds stress fields.
Performance, applicability and limitations
Launder, B. E., Reece, G. J. and Rodi, W. (1975), "Progress in the Development of Reynolds Stress Turbulent Closure", Journal of Fluid Mechanics, Vol. 68, pp. 537-566.