Few if any simulation codes today can manage to solve turbulent flows without including any form of turbulence modeling. A turbulence model essentially introduces an additional (turbulent) viscosity in regions where the grid is unable to resolve the small scale turbulent fluctuations. FEATool does not currently include built-in turbulence models, but it is fairly straigt forward to manually add an algebraic mixing length model as in the attached example [1].

For more accurate and advanced turbulence models it is recommended to use the built-in support for the OpenFOAM CFD solver, as for example in the

turbulent flow over a backwards facing step tutorial model.

[1]

turbulent_channel_flow.fes: Simulation of stationary and incompressible turbulent flow between two flat parallel plates using an algebraic mixing length turbulence model. A fully developed turbulent velocity profile is expected to form at the outflow boundary.

Ref. Laufer, J. (1951) Investigation of turbulent flow in a two-dimensional channel. NACA Report 1053, NACA Technical Note 2123.