URGENT - Need to model water flow through this block

Hello! I need to do this as soon as possible for school, can anyone help?
I need to model the water flow through this reef, however I can not even get the enclosure to work (I do not have the add geometry operation). Please help.
https://www.simscale.com/workbench/?pid=52042838531557186&mi=spec%3A88ba7c9c-3f44-4a39-a11d-62d6dc267c3f%2Cservice%3ASIMULATION%2Cstrategy%3A2

Hi claire
thanks for reaching out to us here in the forum.

Please have a look on how to do fluid volume extractions the get the fluid volume.

You can then have a look at this tutorial on how to set up an internal fluid analysis.

Best regards Sebastian