Hi @Pithikos, thanks for posting and welcome to SimScale 
Since you’re new to SimScale, the best approach moving forward should be to run a few introductory tutorials first to grasp the key fundamental concepts. Here are some which might be helpful:
- Fluid Flow Through Non-Return Valve | Tutorial | SimScale
- Aerodynamic Flow Behavior Around a Vehicle Tutorial | SimScale
- Tutorial: Compressible CFD Simulation of a Golf Ball | SimScale
Then, I’d also advise you not to go for a Multiphase study, at least not until you are a bit more familiarized with SimScale/CFD. You can instead try a single phase Incompressible study by creating a flow region similar to this:
Cheers
Igor