thickenexp{
move the given part of the boundary by a relative value, correlated to the locally given smoothing length
Thicken the geometry by moving the node points of the defined geometry parts.
thickeningDistance = the distance the boundary elements have to be moved is given by \( D_i = \text{thickeningDistance} \cdot H_i\), i.e. the parameter thickeningDistance is relative with respect to the local smoothing length.
N_ThickeningLoops = the moving of the distance \( D_i\) is subdivided into N_ThickeningLoops steps.
EXPERIMENTAL only.