Literature review RANS derivation and analysis

Reynold’s stress:

It is the total stress value obtained in the turbulence region after averaging. Getting this Reynold’s stress correct is what turbulence modelling is all about.

Turbulence model is all about capturing the time integral term in the equation.

Turbulent viscosity:

Generally viscosity is the measure off fluid’s resistance to flow and it is a ratio of shear stress and velocity gradient.

Turbulence viscosity is the viscosity which occurs when there is eddies in the turbulent flow, which are difficult to predict. Generally, the turbulent viscosity will be higher than the laminar viscosity.

Molecular viscosity generally occurs between two fluids when flowing.