In addition, especially for the zero-equation models, any element in the free-flow domain interacts with the walls,

e.g. this defines the wall distance which is needed to calculate the eddy viscosity.

To get all these interactions, you have to call `stokesProblem->updateStaticWallProperties()`

in `ex_turbulence_coupling_ff-pm.cc`.

However, there is also a solution-dependent component of these interactions, e.g. for a correct

damping of the eddy viscosity toward the wall, the velocity gradient at the wall and inside the

cells is needed.

These dynamic interactions are to be updated by calling `stokesProblem->updateDynamicWallProperties(stokesSol)`

in the time loop (after `// update dynamic wall properties`).

Compile and run your new coupled problem and take a look at the results in Paraview.

In addition to the standard variables and parameters, you can now choose turbulence model specific quantities (e.g. the turbulent viscosity `nu_t`) for the free flow domain.

In addition to the standard variables and parameters, you can now analyze turbulence model specific quantities

(e.g. the turbulent viscosity `nu_\textrm{t}` or the turbulent diffusivity `D_\textrm{t}`) for the free flow domain.

In paraview you may compare the magnitude of `D` and `D_\textrm{t}` to see where the transport is affected by turbulence.

The result for the turbulent viscosity should look like this: