Prior to a volume mesh being imported, a new or existing simulation has to be opened. Once this is done, you can import a volume mesh using one of two methods in the STAR-CCM+ workspace.
The first method is to select the File > Import... menu item.
Alternatively, click the 
(Import) button, which is part of the System toolbar.
The standard file import Open dialog panel will appear.
The file to be imported should be selected. You may select more than one file to import if desired. Even though these file types are filtered according to the mesh file types in the Files of Type drop-down list, if you have numerous files of these types with a common name within your directory, you may want to restrict the selection even further. To do this, simply type the common name and an asterisk with the extension of the file type you want into the File Name text box. For example:
This changes two attributes of the Open dialog:
Select the mesh file that you want to import and click the Open button. The Import Mesh Options dialog will appear:
By default, the dialog will have the Run mesh diagnostics after import option turned on and Open geometry scene after import turned off. Note that any selections you change in this panel are permanently remembered by STAR-CCM+ for all future sessions when using the same version of the software.
On pressing the OK button, an import progress report will be displayed in the Output window and new regions and boundaries will be added to the simulation tree. Additionally, a mesh diagnostics report and/or geometry scene will be produced if the appropriate option was activated.