I’m trying to run a PX-Q400 cfd simulation (The PX-Q400 is a pressure exchanger used to recover energy in desalination plants).
The PX works by transferring hydraulic energy from the high-pressure concentrated brine stream to the incoming low-pressure feed stream.
There is a rotor inside the device that rotates just by the hydraulic energy. The rotor has multiple ducts inside trough them accures a direct contact between the concentrated brine and the feed.
I don’t even know how to start such a problem because it is not like the other rotating devices( pumps and turbines) and also because there is a contact between two liquids inside one transfers the pressure to another without mixing
Hi @youssef_bouzyad, thanks for posting on the forum and welcome to the SimScale Community 
Your model seems too complex for a straightforward analysis, I would strongly advise that you clean it up and defeature before running a simulation. Here are some general guidances on how to do that:
It also seems you haven’t created a flow region for your model, which is a crucial step in performing these sorts of analysis.
Our users also tend to agree that running 2-3 introductory tutorials before going to their own models is also very helpful in getting up to speed with SimScale: SimScale Tutorials and User Guides | Cloud-Based CAE | SimScale
Cheers
Igor