34.1.2 File/Read/Case...

The File/Read/Case... menu item is used to read in a ANSYS FLUENT case file (extension .cas), or a mesh file (extension .msh, .grd, .MSH, or .GRD) that has been saved in the native format for ANSYS FLUENT. See Sections  4.2 and 4.3 for details.

The File/Read/Case... menu item opens the Select File dialog box (see Section  2.1.6) which allows you to select the appropriate file to be read.