Anyone can help me to understand how I can reduce the range of volume ratio and aspect ratio in this project? I tried changing some of the settings, but I can’t go under 250.
Hi @Raffreddore,
Thanks for posting your question! I have set up a new basic mesh, the volume ratio is a little bit better (127) so I just started a new simulation and it is running well until now.
Please feel free to make a copy and do your own improvements 
best,
Thank you very much @goncalves , I’m not familiar with the hex dominant mesher, now I’m trying to improve the mesh on the head. Can I ask you other few questions?
My goal is to calculate lift and drag, force and coefficients, for the coefficients, what is the reference area that I should use? The one of the section or the one of the entire missile?
Thank you.
Can anyone explain me why there are these imperfection on the missile geometry? And also I have a lot of oscillation in the inlets and outlets, this is the project.
Up [https://www.simscale.com/workbench/?pid=9005458591595931902&mi=spec%3A09988abe-58f6-41ad-87e6-2d9d8833c06a%2Cservice%3ASIMULATION%2Cstrategy%3A128].(https://www.simscale.com/workbench/?pid=9005458591595931902&mi=spec%3A09988abe-58f6-41ad-87e6-2d9d8833c06a%2Cservice%3ASIMULATION%2Cstrategy%3A128)
I can’t handle the little error on the geometry, but I think the mesh is good. I need to simulate at different angle of attack to produce the Cl(alfa) curve, and now at 16° I have an error of maximum iterations for temperature. Anyone can suggest me how I can fix this?
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Hi @Raffreddore,
I wanted to lend you a hand with this simulation as well. Any reason why you are running it as laminar flow? What is the Reynolds number you are attempting to simulate?
–Nolan
Hi @nhalliday , thank you for the interest! You already found one error, Reynolds is 1,887x10^10, so it isn’t laminar for sure. Can be the problem for the maximum iterations error? I have also some more questions: is it possible to run parallel simulations with different angle of attack and different directions for lift and drag? And for the reference area is correct to use half of the circle’s area?
Yep…I would recommend k-w SST turbulence model for starters. I doubt this is the problem w/ convergence, but it will certainly be more sound from a fundamental perspective. Your very thin fins are likely the cause of poor mesh quality, and thus divergence.
You can adjust the AoA using the inlet velocity components, however you will need to update your reference coord. system to ensure that lift and drag are in the appropriate flow dimensions (it currently cannot be parametric).
Since you are running half-symmetric, you will want to enter half of the area as a reference (otherwise coefficients will be halved).
–Nolan
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@nhalliday
But why the divergence happen only from a certain AoA?
Now I’m trying with k-omega, but the error start from the beginning. Do you suggest to simplify the 3d model of the fins to solve?
Yes, I would thicken the fins and add some leading and trailing edge mesh refinement. Additionally, volumetric refinements near the body may help.
Hi @nhalliday, I simplified the geometry and I meshed it, all the parameters seems good, but the simulations doesn’t run because of the maximum iterations error, since the AoA of 0°. I don’t know how to manage the problem. Any suggests?
Thank you.
With the relaxation type set on automatic, I finished the run with AoA=0°, now I tried with a bigger angle, like 16, and it reaches 17% and then fail again.
I solved the problem decreasing the velocity and do a incompressible one. Now I don’t know what mesh is better for my case, I tried two simulations at 45° with two different refinement dimensions, and the difference between the aerodynamic coefficient is a little bit high: Cl=5,13 and Cd=6,74 for the second one and Cl=3,75 and Cd=6,37 for the first one. What’s the better mesh or the more accurate one? Why the difference is so high?