After eliminating errors/possible problems from a tetra mesh, you can improve the mesh quality using Edit Mesh > Smooth Mesh Globally.
The smoother modifies the elements with quality below the specified Up to quality value, based on the selection from the list of available quality criteria. Nodes can be moved and/or merged, edges are swapped, and in some cases elements are deleted. This operation is then repeated on the improved grid, up to the specified number of iterations. You can choose to smooth some element types while freezing others.
The triangular surface mesh smoother operates independently of the volume mesh smoother. Initially, all elements that are below the quality threshold of the specified criterion are marked, and then the specified number of smoothing steps are run on those elements. Nodes movement is constrained to the actual CAD surfaces during the smoothing process.
- Smoothing iterations
This value is the number of times the smoothing process will be performed. Models with a more complicated geometry will require a greater number of iterations to obtain the desired quality, which is specified for Up to quality.
- Up to quality
The Min value represents the worst quality, while the Max value represents the highest quality elements. Usually, the Min value is set to 0.0 and the Max value is set to 1.0. The Up to quality value gives the smoother a quality to aim for. Ideally, after smoothing, the quality of the elements should be higher than or equal to this value. If this does not happen, you should employ other methods of improving the quality, such as merging nodes and splitting edges. For most models, the elements should all have ratios of greater than 0.3, while a ratio of 0.15 for complicated models is usually sufficient.
- Freeze
If the Freeze feature is selected for an element type, the nodes of this element type will be fixed during the smoothing operation. As a result, this element type will not be displayed in the histogram.
- Float
If the Float feature is selected, the nodes of the specified element type will be capable of moving freely, enabling nodes that are common with another type of element to be smoothed. The quality of elements set to float is not tracked during the smoothing process and so the quality is not displayed in the histogram.