Check the validity of the mesh using Edit Mesh > Check Mesh. ICEM CFD includes several checks for Errors as well as Possible problems. The descriptions of each of these checks can be found in Check Mesh in the Ansys ICEM CFD Help Manual.

You can opt to use the Create subsets feature for each of the problems so that they can be fixed later or can opt to use the Check/fix each feature to check and fix each one of them. Using subset manipulation and mesh editing techniques, you can diagnose the problem and resolve it through merging nodes, splitting edges, swapping edges, delete/create elements, and so on.

For ease of use when working with subsets, it is usually helpful to add elements to the subset in order to see what is happening around the problem elements. To do this, right-click the Subset name in the Display tree and then add layers of elements to the subset. It is also useful to display the element nodes and/or display the elements slightly smaller than actual size. Both of these features can be accessed by right-clicking on Mesh in the Display Tree.