To Reverse the Direction of Mesh Element Normals

Select the Change Mesh Normal tool ( Modeling > Mesh > Modify Meshes ).

Select the option Reverse Vertex Order around all facets.

Click the extended tool settings arrow and in the Display drop-down select Face Normals.

Select the mesh element.

The mesh highlights, with graphics displaying the current normal of each facet.

Select the Change Normals button in the tool settings window. The direction of the mesh normals is reversed.

Enter a data point to accept.

These graphical normals are scaled by facet size. If the mesh has attached normals (for example, from the Facet Smoothing tool), these normals are displayed, one at each corner of each mesh facet.