Hey guys, brand new here and trying to get into CFD with a pretty simple project. I came up with a very basic CD Nozzle geometry using essentially just 3 lines on a 2D Sketch and then revolving that around an axis to get the 3D geometry. My problem comes when I try to import that 3D geometry into simscale. I convert the 3D part file from Autodesk into an STL file and get it to upload properly, but the geometry that gets imported is strange in that simscale creates multiple different faces on the nozzle where there is not intended to be any (kind of vague wording I know, but hopefully the pictures help). My questions are how do I refine my geometry in Autodesk so that I can properly import it and get a decent CFD analysis on the nozzle?
Also, this is my first CFD simulation so any advice on how I could perform the analysis would be GREATLY appreciated. Is it as simple as selecting the inlet of the converging section to be a velocity inlet and assigning a value for the velocity (just assuming air for now as the material for simplicity) and then assigning a pressure outlet at the end of the diffuser section? (I guess assume ambient pressure for ideal nozzle case?) Or is it a better approach to do an external flow analysis and have the flow volume pass through the nozzle?
As a little background, I actually milled out a nozzle with almost the exact geometry of the part file that I am using for this analysis and tested it in a Paraffin/Nitrous Oxide Hybrid Rocket and it performed very well so I am just trying to use the CFD analysis to verify the results I got from my static firing. Additionally, if there are any other files you need or clarification, let me know and I’ll try to provide it! Again, I am brand new at this so I apologize if my questions are kind of vague or it seems like I don’t know what I’m talking about (because I don’t! )