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#1 |
New Member
Robert
Join Date: Nov 2022
Posts: 14
Rep Power: 3 ![]() |
I am working on the multiphysics tutorial from SU2, specifically the static CHT simulation.
I am looking to recreate a very similar simulation, using a larger grid with more obstacles. The issue I’m running into is creating the mesh as I don`t fully understand the structure. The mesh I created uses a farfield, outer cylinder wall and inner cylinder wall. The mesh uses multiple zones but modelling it in GMSH seems tricky. 1. The tutorial defines a third zone called Core1 for the cylinders. I am struggling to understand what this mesh represents. 2. Is the cylinder thickness modelled as a surface? I would be delighted if anyone could shed some light over how would one generate the mesh from said tutorial: https://su2code.github.io/tutorials/Static_CHT/ |
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#2 |
Senior Member
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 596
Rep Power: 17 ![]() |
1. The tutorial defines a third zone called Core1 for the cylinders. I am struggling to understand what this mesh represents.
The cylinder is hollow and we set the wall temperature of the inner circular boundary. This would be akin to a hollow tube with cooling water running through it. In this setup, the cooling water is not simulated, only the hollow tube. We simply assume that the water keeps the wall of the water channel at a constant temperature. 2. Is the cylinder thickness modeled as a surface? Yes, all physical 2D zones are surfaces. here is some further info: https://su2code.github.io/docs_v7/Multizone/ |
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#3 | |
New Member
Robert
Join Date: Nov 2022
Posts: 14
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#4 |
Member
Ole Burghardt
Join Date: Mar 2016
Location: Kiel, Germany
Posts: 60
Rep Power: 10 ![]() |
Hi,
there are four physical zones (sub-meshes, if you like) in the mesh, one for the fluid flow zone, three for the solid zones. The boundaries in the fluid flow mesh are called farfield, cylinder_outer1, cylinder_outer2 and cylinder_outer3. The boundaries in solid zone mesh X are called cylinder_innerX, coreX. (The solid zones are annuli, the outer perimeter is called cylinder_inner, the inner perimeter is called core.) The CHT coupling between the fluid zone and the solid zones is formed by exchanging data between cylinder_outerX and cylinder_innerX. At the cores, a temperature boundary condition is imposed. For meshing it might be easiest, or actually the only way, to create meshes for each domain seperately and to concatenate them later on. The mesh file used for this tutorial is in text format, just check it out to see how it's done. Does this help? :-) |
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#5 | |
New Member
Robert
Join Date: Nov 2022
Posts: 14
Rep Power: 3 ![]() |
Quote:
Thank you for the advice. You have opened my eyes! It worked!!!!! The answer to my question is exactly your suggestion i.e. concatenate the meshes together. Still have a long way to go as for optimizing and everything but you might have saved a poor's student's week haha! |
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#6 |
Member
Ole Burghardt
Join Date: Mar 2016
Location: Kiel, Germany
Posts: 60
Rep Power: 10 ![]() |
You're welcome :-)
Just out of curiosity, what are you working on? |
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#7 |
Member
na
Join Date: Jul 2018
Posts: 90
Rep Power: 8 ![]() |
Just to add a little bit of resource/inspiration that might help with a few things:
1. video that covers general aspects of multizone simulations/setups https://www.youtube.com/watch?v=ez368rDYrFk (no guarantee that everything is still up to date, but e.g. the mesh concatenation definitely is) 2. A repository with a few gmsh meshes (also a few multizone ones, inidicated with e,g, '2zones' in the folder name). Take e.g. folder '18__3D-2Zone-pin-in-crossflow' for an easy setup. I pretty much only made structured meshes so setups might be easier for you but I generally create the interface boundary at the beginning that gets used for all relevant zones to have a single source of origin, all zone-specific stuff then comes later in the file https://github.com/TobiKattmann/Meshes/ Maybe this of use for you |
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#8 |
New Member
Robert
Join Date: Nov 2022
Posts: 14
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#9 | |
New Member
Robert
Join Date: Nov 2022
Posts: 14
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#10 |
Member
Ole Burghardt
Join Date: Mar 2016
Location: Kiel, Germany
Posts: 60
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Sounds like wrong settings or a corrupted mesh. We'd need to have a look on the output and/or config files
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#11 | |
New Member
Robert
Join Date: Nov 2022
Posts: 14
Rep Power: 3 ![]() |
Quote:
I'm attaching the config file here and a snip of the mesh, maybe you can have a look. The one thing that I can see different between my mesh and the tutorial is that I am using an unstructured grid and obviously a different array with more cylinders. Unfortunately, I can't seem to upload the mesh as it's too large. The markers that I am using are "Inlet" and "Outlet" for left- and right-hand sides, "cylinderx" (x = 1:15) for each cylinder surface and symmetry for the top and bottom sides which exclude the cylinders. |
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#12 | |
New Member
Robert
Join Date: Nov 2022
Posts: 14
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Quote:
The config file for this is attached along with the resulting history excel file. |
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#13 |
Senior Member
bigfoot
Join Date: Dec 2011
Location: Netherlands
Posts: 596
Rep Power: 17 ![]() |
Is this last case a fluid-domain simulation only? What is the mesh quality of the mesh? And the Reynolds number? The mesh also looks extremely fine close to the cylinder walls. For such simple meshes it can be very beneficial to use structured meshes instead of unstructured meshes.
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#14 | |
New Member
Robert
Join Date: Nov 2022
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Tags |
cht modelling, gmsh, gmsh cylinder, mesh, su2 |
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