All simulation studies are solved on the cloud, and rely on cloud computational services to do so.
If you start an analysis, and you exit Fusion before the files are uploaded to the cloud solver, you'll see a warning. You can Quit Now, which cancels the pending study, or cancel and wait for the upload to complete.
If you close a project while studies are solving, the results are downloaded for viewing when you reopen the project.
If you make changes to a study after you have solved it, results listed in the Results browser are marked as out of date with a warning.