Hi everyone! I’m working on my first external aerodynamics study to learn CFD. I’m trying to predict the drag and lift coefficients of a vehicle prototype using ANSYS Fluent Student, with a mesh limit of around 1 million cells. I’ve been having trouble with convergence and choosing an appropriate near-wall treatment.

From what I’ve read, k–ω SST is commonly used for external aerodynamic simulations, often with a mesh targeting y+ ≈ 1 or lower to resolve the near-wall region. However, achieving this while adequately refining the rest of the domain is challenging within my cell limit.

I’m also considering realizable k–ε with a wall-function approach targeting y+ > 30. My understanding is that this could reduce the near-wall mesh requirements, although predicting separation under adverse pressure gradients may be more challenging. I’m unsure which near-wall treatment would be appropriate: standard wall functions, scalable wall functions, non-equilibrium wall functions, or enhanced wall treatment.

The vehicle uses narrow bicycle-type wheels, and the rear wheel is enclosed by a fairing. One geometry-related question is whether I should include the air cavity between the rear tire and its fairing, or simplify that region. What level of detail is appropriate for this type of simulation?

My current setup is:

• Steady-state RANS with k–ω SST.
• Inlet velocity: 8 m/s.
• A symmetry plane.
• Rotating-wall boundary conditions for both wheels.
• A moving ground.
• No rear tire cavity volume (fully closed).

As for the mesh:

• 1M cells.
• Minimum orthogonal quality 0.12
• Body of influence regions and local sizing.
• Last Ratio method and 15 boundary layers (first cell height adjusted)

I estimated the first-layer height to target y+ < 1 and ran the simulation, but the drag and lift coefficients did not settle to constant values.

I’d appreciate some advice on the following:

1. Are there any obvious problems with my mesh or near-wall approach?
2. How can I distinguish numerical convergence problems from flow behavior that may require a transient simulation? Or perhaps it is a geometry issue.
3. Within the cell limit, would you prioritize an SST mesh targeting y+ ≈ 1, or consider realizable k–ε with wall functions?

I’ve attached the drag and lift coefficient histories, a mesh view, a y+ contour, and a velocity plot.

Any feedback would be appreciated. Thanks!

Y+ Contour seems to be fine without going in between de 5-30 region.

Has anyone here been working on those gigs where you can do CFD for AI training? I know it's kind of digging my own grave thinking long-term, but has anyone earned decent money from it? I lost my job and have been looking into different alternatives until I find something

Hi everyone! I'm interested in learning SIMULIA XFlow for CFD simulations, particularly for aerospace applications.

What resources or tools would you recommend for a beginner? Are there any good tutorials, documentation, sample projects, or YouTube channels to help me learn the software?

I'd appreciate any tips from those who have experience using XFlow. Thanks!

Guy's actualy iam doing an final year project , in this we will aim to improve the aerodynamics performance an existing RG-15 airfoil throungh an bio inspired , for first bird we have choosen an albatros by this we actualy desinged an airfoil through its wing characteristic , when we do an CFD analysis the result (CL,CD) where abnormal then usual , actualy we all the checked again and again from mesh to setup , we dont know what to do get the result , actualy we have to show the result to our guide tommorow , if you guy's where anybody free, can you do as CFD analysis for us , i will give you an step or iges file of an airfoil and give you an all the parameters to do

I opened VSPAERO on my model, there were no graphs in the convergence or any other tab, and in the viewer tab my model is fully purple and it does not change when i change the AoA. Any advice would be helpful, i heard there might be a problem with vertical the stabilizers but there should not be the problem since i dont have one in my model. I have a basic model with only a stock fuselage and a lightly modified wings, i only wanted to test VSPAERO but i did not expect to run i to such problems on my first try. I also tried a more advanced model but i ran into the same issues.

Hey Folks,

As part of my thesis, I am supposed to carry out a complete melt pool + single bead + multiple bead walls.

For those who don't know what ARC DED is, it's also known as WIRE ARC ADDITIVE MANUFACTURING (WAAM). It's a form of controlled layer deposition incorporating Welding.

Though I am not new to Fluent, my only superpower is replicating a video, and on my expectations youtube is filled with Demonstration videos than case setup. Literatures does provide a model overview, equations that will be used, but far from setting up.

CFD is being done so that complete surface morphology, effect of gravity, maragoni forces, shear, surface tension, etc are captured.

Kindly assist in Model Development.

​

I'm looking to build or purchase a top of the line CFD workstation specifically for computationally intensive marine hydrodynamics simulations, turbulent flows, rotating machinery, and complex boat geometries.

My primary tools are ANSYS Fluent and OpenFOAM, with simulations potentially involving 5-10 million mesh cells, transient flow analysis, and multiphase CFD.

I'm particularly interested in recommendations regarding:

1. CPU: AMD Threadripper PRO vs AMD EPYC vs Intel Xeon. Is 64 to 96 cores the sweet spot, or are there diminishing returns?

2. RAM: 256 GB, 512 GB, or 1 TB for large transient simulations?

3. GPU: Do NVIDIA professional GPUs provide meaningful acceleration for these applications?

4. Storage: Optimal NVMe SSD configurations for massive CFD datasets.

5. Parallel performance: How well do Fluent and OpenFOAM scale with increasing CPU core counts?

6. Hardware: Would you recommend a powerful single workstation or a small computing cluster?

My background is biology and I'm particularly interested in hearing from engineers and scientists in the CFD marine Hydrodynamics field running serious marine CFD simulations rather than synthetic benchmarks.

Real world experiences, solver benchmarks, and complete hardware configurations would be greatly appreciated! Thanks

I have been given a simple 2D rectangular mesh file. I can adjust the height and length of this with Mesh -> Scale... easily enough, but then the grid cells become compressed where I have reduced the length.

Adapt -> Manual... or Automatic... and selecting the channel as a region (both the exact size, and a region slightly larger than the grid) hasn't worked with any combination of coarsening settings I've tried so far to decompress them.

Meshing mode doesn't work with the mesh file I have, no edge groups, no way to visualise it etc, and in the context of the course I'm doing I'm assuming it can be done in Solution mode somewhere.

How do I simply change the number of cells in the x and y directions?

Hola, soy nuevo en esto del CFD, vengo del diseño orientado a los vehiculos y quiero empezar a agregarle calidad y valor a los proyectos con un estudio CDF.

Empecé hace una semana a ver y probar Ansys Discovery con la version gratuita.

Puedo realizar una simulacion basica pero no entiendo como analizarla para modificar o no el modelado.

Muchas gracias!

So iv been working on this project for a couple of months, I wanted to show it because I finally believe it is a bit presentable now, it is basically a gui with openFOAM, and additionally I added TENO schemes from Fu et al, I thought it was an interesting paper and I wanted to add higher order schemes to achieve higher accuracy (note that I also like swirly lines), going through this project I will be extending it to Ji, Liang & Fu 2021 for unstructured meshes when I have the time. Since most of the coding in this project is human slop, apologies in advance for any bugs that may arise (I lost sleep because of segfaults in cpp)

Source code: https://github.com/CakeCFD/cake-studio

Website: https://cakecfd.org/

I would like opinions from fellow engineers on how to improve this further and make this better, or more specifically what validation case would you trust before using the TENO schemes?

So, im a first time poster so pls be kind :) Also english isnt my first language so excuse any mistakes in my writing

Anyways, I just started my masters in computational mechanics, and I only had some basic knowledge on the subject from my postgrad (plus I only know C++, Matlab and theoretically fortran but not really). They just told us to write a code with a basic grid (like 3x3 or 3x4) and create a NOP(I,J) function, where I is the number of elements (square elements), J is the number of local nodes (J=1,...,4), and the output should be the global node corresponding to a specific local node of a specific element or something like that. Forgive me if the explanation is garbage, I understand it theoretically but not 'computationally' per say.

Does any kind human 1) have any idea of what i'm trying to say and 2) know how to actually help me? for some reason i cant find ANYTHING by googling, and no reddit posts as well (may have missed though). even AI cant help even though i prefer not to use it

Ty for reading xxx

I’m doing bachelor in Mechanical engineering. I’m interested in learning but don’t know where to start from can you give some beginner friendly tips and should i learn open foam or ansys

Im still in school & ik im gonna major in aero so i got openfoam a couple of months ago but never got the chance to learn.

Hey everyone!

I'm a 31-year-old mechanical engineer with several years of experience in Oil & Gas (Project Engineer), Tool Installation (Team Lead), and currently BIM (Technical Expert / Mechanical Piping Modeler).

My dream has always been to work in automotive or aerospace engineering, especially in design and aerodynamics. However, career opportunities led me elsewhere, as these fields are almost nonexistent in my country due to the lack of R&D.

Now that I've graduated, I'm considering pursuing a Master's in Computational Mechanical Design in Europe to transition into CFD, aerodynamics, or mechanical design.

My question is: Is this a realistic career move at 31, with no professional experience in CFD or design? Would my previous engineering experience be valuable, or would I essentially be starting from scratch?

Thanks for your time!

I've been trying to use Ansys fluent (Student version) but everytime I start the program I get this warning saying that there's no license available. Workbench runs fine. I've also got similar problems when I open any of the other Ansys programs (as shown in the second image).

I've already checked that the program has access through the firewall to both private and public networks and I've tried uninstalling and installing again but the problem persists.

I also checked a similar post in this same subreddit and saw people mentioning the number of nodes or processes as a problem with the student license. Following the advice there, I tried running Fluent with 1, 2, 3 and 4 processes having the same issue each time.

I hope someone will be able to help me figure this out.

In the era full of low job availablity(especially for freshers in CFD),,, what makes you love CFD, or be in this subs... You can directly learn some other skills and have good initial salary.. Right???

I wanted to see the temperature contour of Heat exchanger but it's been more than 1 hour still it's loading any solution?

I have some conceptual doubts, which I didn't get clear explicit answer from sources in net,

1) What is difference between node values on/off in looking the contours? I observed values are relatively higher when I turned off node values. Please tell me cases or situations where we should turn on or turn off node values with reason. How does this affect in viewing contour, finding range of parameter in some selected surface or cell zones.

2) I have some trivial doubt about operating pressure. The point is- In momentum equation , it contains pressure gradient not absolute pressure, so fluent choose some reference pressure i.e operating pressure. So instead of solving with very large pressure, it works with smaller numbers since deltaP remains the same with the concept of operating pressure. Density is calculated using absolute pressure only.
This concept is same for both incompressible and compressible flow right, but why do they say for compressible flow you have to set operating pressure as zero, I didnt understand what is the reason for this? Can anyone explain elaborately please? Thanks in advance.

this 2d cfd sim uses upwind differencing schemes and uses ndarray and rayon to ensure its fast so im confused as to what to do with the tiny dt caused by cfl conditions and heres the tiny project
https://github.com/busysofa15/2026_projects/blob/534578f75d4ce511587d2f012a219a9b95a588e0/rust_projects/compressible_fluid_sim/src/main.rs
and the dt condition is around lines 86 to 99
any help would be appreciated 👍️

I'm signed up to take the Programming CFD training w/ Greenshields next month. I haven't done any OpenFOAM trainings with them before.

Anyone here completed the training? If not Programming CFD, one of the other ones? From what I've read they're really good. I'm mostly interested in the training material and book I can take back with me.

Hi everyone,

Video #8 of the (free) turbulence course I'm creating is now up on YouTube. This one is very much applied where I take a PIV time series, generated from the cover video, of a turbulent jet and compute flow statistics in MATLAB, explaining each step.

It covers the mean and fluctuating velocity profiles, going further into Reynolds stresses (normal and shear), and then longitudinal and transverse two-point correlation functions and second-order structure functions relative to the centreline.

The scripts are deliberately short, so they're meant as a template for anyone who wants to run the same statistics on their own PIV, hot-wire or numerical simulations data.

Link: https://www.youtube.com/watch?v=Z7Q0k4P1V8k

Notes (and scripts) are available on Patreon (free membership option available). Happy to answer questions about the analysis.

Hello everyone,

I've been trying to get this benchmark propeller (Potsdam Propeller Test Case) analysis to work but I can't mesh it with SHM. Inflation layers are not good enough and I can't get the desired y+ values for the case.

I also need some kind of surface refinement or wrapper. The geometries I use have self intersections that are easily handled in StarCCM+ but with snappy, checkMesh finds errors due to these bad STL elements.

What is your go to method for meshing thin lifting surfaces like wings, propellers etc.? I am honestly losing my mind trying to get it to work. I really need some help.

Thank you all in advance.