Until recently, I had never used ICEM CFD for meshing and primarily used ANSYS Meshing. However, I desired a higher quality mesh composed of hexahedrons and switched to ICEM CFD. After completing all of the available tutorials for structured meshes, I still have a few questions unanswered.
I'm quite familiar (I think, haha) with Meshing, so I was used to preparing a geometry in DesignModeler for Meshing. For example, combining bodies as a Part in DM will result in a conformal mesh in Meshing. And within Meshing, I'd create Named Selections (e.g., pressure_outlet, etc) so Fluent would detect that selection as a pressure_outlet. I'm not quite sure how to go about this for ICEM CFD. Before going on, below is my project schematic (ANSYS v17.2)
My geometry was created in DM. It's a single expansion ramp nozzle, ~1.5 Mach jet perfectly expanded. The fluid domain itself consists of the [internal] fluid nozzle body and an external flow field, pictured below. Currently, I have 3 bodies: the nozzle body; an inner external fluid body (the cylinder-cone-cylinder shape); and the outermost external fluid cylinder body. All bodies are "Formed as a Part."
In DM, I created Named Selections for all of my boundaries: 3 pressure_outlets (faces on the external fluid bodies), 1 pressure_inlet at the nozzle inlet; and the inner and outer walls of the nozzle. These selections appear to pass through to ICEM as expected. However, several "parts" get added when viewing the Parts tree in ICEM. Referring to the below pic, the parts with the # character (e.g., fluid_nozzle_1#fluid_domain_inner_3) get created when I first open ICEM. What are these? I assume they're the shared faces between the bodies. How should I treat these in regards to boundary conditions? Should I not have the bodies formed as a Part in DM? How will this affect Fluent setup?
Furthermore, the parts B1 and B2 are parts I created in ICEM when I started blocking. The way I did it was by deselecting/hiding the external flow geometry so only the nozzle itself was visible. I then created initial block B1 by selecting all visible nozzle curves. Once finished blocking the nozzle, I hid B1 and all nozzle parts and enabled all external flow parts and created another initial block B2. When I create B2, I'm prompted whether or not I want to merge or replace the existing blocks: I select merge. I then make a handful of splits, o-grids, etc for the external domain.
How I should proceed after I'm done blocking and setting pre-mesh params is where I'm a little foggy. I did go through the Output Mesh tab and apply settings for boundary conditions...but I'm unsure of what to apply to every part listed in the above pic. Pressure_outlets, pressure_inlet, and walls are all self explanatory but I'm lost on what to do all components under PART_1. Should I leave their boxes checked/enabled? Or unchecked/disabled? Or do I even need to change settings for boundary conditions in the Output Mesh tab since I already created Named Selections?
In the grand scheme of things, my intent is to run LES in Fluent and use the acoustics model to predict far-field noise. Since I plan on using the acoustics model, I'll need to be able to select a surface for a sound source (preferably one which surrounds the jet such as the cylinder-cone-cylinder surface). What I expected to have are 3 fluid zones, 3 pressure_outlet b.c.'s, 1 pressure_inlet b.c., 2 wall b.c.'s, and several interior zones. I should have NO mesh interfaces or at least that's how Fluent interpreted meshes I created in Meshing. Anytime I had mesh interfaces in Fluent, I ended up having covergence difficulties for some unknown reason.
I could really use some pointers! I completed more than a majority of ICEM tutorials...enough so that I was able to get a much better mesh than I previously had in Meshing. It's just the fine details I don't know of. I knew what I was doing, for the most part, when using Meshing but I'm unsure of how to handle preparing geometry for meshing in ICEM and consequently Fluent. I appreciate any help!