The Mesh Settings menu item controls mesh generation behavior.
Use Mesh Constraints:  When enabled, the mesh settings in the following group box will be applied  the mesher will ensure that triangles satisfy the specified parameters such as interior angle. When disabled, a more direct meshing approach is used, resulting in faster meshing with the fewest possible number of triangles output to fill the mesh. 
Maximum Triangle Area:  This option defines an upper limit to the triangle size of generated mesh, in square units. A smaller number will create more triangles, so use care to avoid overrefinement which may significantly increase model run times. Leave this value blank for no upper limit on size. (Recommended: no limit) 
Minimum Interior Angle:  This option controls the dimensions of each mesh triangle. The default of 20 ensures that every triangle has a minimum angle of 20 degrees on each side. Larger angles may lead to unsolvable meshes. (Recommended: default of 20) 
Merge Distance:  This option limits excessively dense meshes, by merging node points that are closer together than the specified distance. The smallest allowable value is 0.001 (one geodecimal), the smallest accuracy supported by SVOFFICE. Keeping this value relatively large will help prevent the creation of very small or thin triangles during meshing. (Recommended: as large as possible based on accuracy requirements) 
Intersector Tolerance:  Specifies the tolerance distance used when performing surface intersection actions. Any points that are within this distance to another point or triangle will be adjusted such that there is no gap between the points or triangles. The default value of 1e12 is recommended and is least likely to cause problems when performing complex intersections. If problems with the mesh are encountered after performing an intersection, it may be useful to adjust this setting. 
