When a model is loaded, the default Element Size is automatically set by the software using the physics preference and characteristics about the model.
If the model only has solid parts, the Element Size is set as a factor of the Bounding Box Diagonal. When Use Adaptive Sizing is set to Yes, the factor is determined by using a combination of the Physics Preference and Initial Size Seed. For other sizing options, the default Bounding Box Factor is set to 0.05, but you can modify this in the Options dialog box ( Tools > Options > Meshing > Bounding Box Factor ).
If the model has sheet parts, the Element Size is set as a factor of the average surface area. When Use Adaptive Sizing is set to Yes, the factor is determined by using a combination of the Physics Preference, and Initial Size Seed. For other sizing options, the default Surface Area Factor is set to 0.125, but you can modify this in the Options dialog box ( Tools > Options > Meshing > Surface Area Factor ).
Other default mesh size settings, such as defeature size, curvature minimum size, and proximity minimum size, are set in relation to the Element Size. If Use Adaptive Sizing is set to No, a simple factor is used to scale the defeature size, curvature minimum size, and proximity minimum size.
Beginning in Release 18.2, you can rely on dynamic defaults to scale other sizes off of the element size. When you modify the element size, the other default sizes update dynamically in response, thereby providing a more direct scaling of sizing values.
Dynamic defaults are controlled by the Mechanical Min Size Factor, CFD Min Size Factor, Explicit Min Size Factor, Mechanical Defeature Size Factor, Explicit Defeature Size Factor and CFD Defeature Size Factor options. These options are available in the Options dialog box. You use these options to set your preferences for the scale factors that will be used to calculate the corresponding default sizes. Essentially, the scale factors control the default values for global minimum size and global defeature size, as well as the default sizes used by local mesh sizing controls when Type is set to Factor of Global Size .