A mesh node is a point within the mesh with unique spatial coordinates. Multiple nodes (4,8,10 or 20) make up a surface (2D) or volume (3D) element.
The FE solver computes displacements at the nodes (The displacements within the volume of the element are interpolated using the nodal results).
What are mid-side nodes?
There are nodes located at the vertices of an element. Some elements (quadratic or higher order elements) have nodes at the mid-points of the element edges. Note that in a default ANSYS mesh, the nodes are not shown.
The figure below shows a depiction of 20 node element. One easy way to view the nodes for this element is to pick the nodes selection filter and draw a selection box around the element. The nodes will highlight in green as shown in the image on the right in the figure.
