Does occlusion culling unload meshes or just not render meshes?
Please post questions properly, more than 1 line would be nice 
Before answering the question I would like to make you aware of the speed of harddrives. What do you think would happen when an object comes into view if it was unloaded?
Also I would like to make you aware of the fact that this can be answered by looking up Occlusion Culling on the googlez. Please do so in the future before asking questions
Now that you know how to answer the question for yourself, my work is done.
Thank you,
Benproductions1
PS: In the case you are not able to answer this for yourself (unlikely): It just doesn’t render them