add necessary binding (#253)

Author: Victor-M-Gomes

src/model/mesh/pywrap/include/bindings_model.h

@@ -61,7 +61,10 @@ void bind_modelapi(py::module_ &m)
       .def("get_number_of_faces", &T::getNumberOfFaces)
       .def("is_boundary_face", &T::isBoundaryFace)
       .def("get_global_node_from_face", &T::getGlobalNodeFromFace)
-      .def("get_global_face", &T::getGlobalFace);
+      .def("get_global_face", &T::getGlobalFace)
+      .def("set_free_surface_enabled", &T::setFreeSurfaceEnabled)
+      .def("init_free_surface", &T::initFreeSurface)
+      .def("is_free_surface", &T::isFreeSurface);
 }
 
 // templated binder for one ModelStruct instantiation