Hi guys,

I am a beginner in ICEM CFD meshing. As part of my academic project i need to mesh a 2D geometry using ICEM CFD software. I have started blocking the geometry as shown in the figure and im stuck with one of the geometric feature ( the converging tip). As shown in the figure i have blocked till the tip but at the tip the edges gets overlaped. Is there any technique to block the tip efficiently. Is my way of blocking correct? Also is there any other methodology to mesh.

Images : First picture shows the converging tip. (Aerospike Nozzle) Second image shows the complete computational domain.

Hey everyone,

i dont even know if this is the right sub to post on but here goes..........

As the title says, I’m in desperate need of some hard advice right now. I’m 20 and currently in my 3rd year studying aerospace engineering. My ultimate dream is to work as an aerodynamicist—anywhere, honestly, but the dream is Formula 1.

Here’s the thing:

• I’m passionate about aero and CFD, and I’m pretty solid with math and physics.
• I absolutely hate structures and really dislike propulsion.
• My heart is set on aero, but I’m terrified that these preferences might create major roadblocks for me in the future.

My immediate goals are to:

• Learn how to code my own CFD solver—hopefully within the next six months.
• Pursue a CFD and aero-focused master’s program after my bachelor’s.
• Possibly aim for a PhD in the same field.

But here’s where my doubts kick in, and I’d be so grateful for guidance:

• What kind of jobs can I realistically expect with this skill set?
• Apart from simulation, what do CFD engineers actually do in the industry?
• Will being so focused on aero and CFD make me a valid candidate, or am I limiting myself too much?
• Should I branch out and learn propulsion, even if I don’t enjoy it, just to keep my options open?
• What industries (besides aerospace) actively seek CFD skills?
• Does being specialized in aero and fluids pigeonhole me into only niche roles?
• What specific skills or projects can I focus on during my bachelor’s and master’s to make myself more employable?
• Are there emerging fields in CFD and aero where I could apply my skills and stand out?
• For those with experience, how did you build credibility or land jobs in this field?

I feel like I’m running blind here and have no clue about what the job market even looks like for people like me. I’m passionate but so worried about the practicality of my goals. Should I reconsider, or is it okay to stay focused on what Im passionate about?

Any advice, experiences, or suggestions would mean the world to me right now. Thank you so much in advance!

Hi all,

I’m currently working on a project in ANSYS Fluent, and I can't seem to get the results I'm looking for.

I’m designing a vertical axis wind turbine (VAWT) for my thesis and am completely new to CFD. The Reynolds number is relatively low, as the turbine is designed for low-wind environments and needs to be fairly compact (Re ≈ 5 × 10⁴ – 2 × 10⁵). I’ve been trying to validate my CFD method by simulating a turbine, but so far, the results have not been great, with the torque still showing negative values 😂.

Here’s my current setup:

University desktop: i7-12700, RTX 3060, 32 GB RAM.

The simulation doesn’t have to be 3D, but since I was originally planning to simulate both a straight-bladed and a helical turbine, I assume helical turbines can’t be accurately analyzed in 2D.

Challenges I'm Facing:

Mesh Size:

When creating a 3D mesh for validation with a target y+ of ≤2, the element count can quite easily exceed 30 million. Even relaxing this to y+ ≤5 results in around 25 million elements.

This is a bit too computationally intensive, especially for transient simulations. Is this element count typical for my setup, or am I doing something wrong?

Turbulence Model:

Since my simulations can fall into a transitional flow regime (Re < 10⁵), I’ve been using k-ω SST with low Reynolds corrections. From what I’ve read, y+ ≤5 should be ok for this model, but I’m still struggling to reduce mesh size without compromising mesh quality.

Simulation Accuracy:

For the sake of time, I’ve attempted steady-state simulations with frame motion, but the results have been way off. The torque values are either negative or so low that the power coefficient (Cp) is barely 5% at what is supposed to be the optimal TSR. Could this error stem from my mesh, solver setup, or something else I'm not too sure?

Possible Alternatives:

Should I avoid pursuing the helical turbine design altogether and focus on straight-bladed turbines? I could then rely more heavily on 2D analysis, which might save time and some headache. However, I’m unsure if I’d miss out on significant conclusions by simplifying the design, or being limited to only the straight blade turbine.

Mesh Queries:

As y+ decreases, I believe the transition between the blade and the inflation layer worsens orthogonal quality and skewness. To address this, I’ve been refining the blade surface, but this drastically increases the element count, especially refining the trailing edge.

Is this the right approach, or am I missing something?

Any advice on these issues would be greatly appreciated. If you need further details, feel free to ask.

How to determine the downwash of a wing by using ansys fluent

Hi everyone,

I’m currently working on a project in ANSYS Fluent, and I’ve run into an issue that I can’t seem to resolve. I’d really appreciate some guidance from the community!

Problem Details:

• I’m analyzing a 2D airfoil with Re=290537, density= 1.2047, dynamic vis= 1.8205e-5, kinematic vis=1.5111e-5, chord length=1m.
• The specific issue I’m facing is the solution coming near to residual, but not converging at all. I have tried several turbulence models.
• also, the plot of D and CL it is getting fixed result after certain iteration.

Despite my efforts, the problem persists. If anyone has experience with this issue or suggestions on what to check, I’d be incredibly grateful!

Thanks in advance for your help! If additional details are needed, I’m happy to provide them.

Hey, I am a beginner with ANSYS and I am dealing with an issue.

So basically I am working on an ANSYS Fluent simulation and I tried to import an initial case by importing the .cas file and .dat file from a previous Fluent setup I created. However when I Imported those two files the geometry and mesh components dissapeared from Workbench, and I am not sure how I can access them back.

I tried to "Recreate Deleted Components" but I am getting the error message of the attached ss. I dont think the geometry or the mesh is deleted because I can still run simulations on them, I just dont know how to access them.

Any help is appreciated! Thank you!

https://preview.redd.it/xvh4y6sa4h9e1.png?width=191&format=png&auto=webp&s=46ff33010dcc329622176a010d6ef75e96b97203

https://preview.redd.it/dha9m2if4h9e1.png?width=348&format=png&auto=webp&s=70908880744725138a88e7f47a0b91de4199abd4

I'm learning to make my own solver in C/C++. These languages don't have something like matplotlib for python.

What do most people use for this? Do you just format your result and then use Paraview?

I am trying to model a liquid-liquid rocket engine, but am having issues modeling the injector using DPM. It seems like in ANSYS fluent, when two particles collide, they aren’t able to breakup into smaller particles even if collisions and breakup is turned on. I was hoping to take advantage of this to model atomization. Is there a workaround? Do I need to use VOF instead? Or is this possible in another CFD tool? I was looking at trying Converge CFD.

I need to validate drag coefficient values for Re=20 using lattice boltzmann in d2q9 lattice for flow over a circular cylinder. I wrote a code but the values are way off. Can anyone either send me their code if they've done it or dm me and i can send my code and they can see what I am doing wrong.

I have been self-learning OpenFOAM with this guide. The section on finding volumetric flow rates suggests the use of utilities by typing foam ls. There appears to be no such command. The official documentation has the util command, which works, but the folder does not contain the postProcessing/patch/patchIntegrate function.

Am I following an outdated process, or am I missing something here?

Hello all,

Just an announcement that I am creating a Discord server for anyone who wants to collaborate on this write-up. I do not want to publicly post the link so please DM me if you would like to assist! :)

In an effort to keep it as short as possible and keep my personal vision of it intact, I will not be letting anyone have direct editing privileges. You can view the document and see what needs to be added and write up your own paper and send it to me in the server. If I think is worth adding in I will do so!

I need a lot of help with writing up an overview of the governing equations in a way that is easily digestible and low on the jargon. This is my weak spot and I know there are some bright fellows out there who may not know CFD well but have a great handle on the equations of fluid dynamics. Other parts like writing short sections to briefly explain characteristics, hyperbolic PDEs, conservative forms, etc. are also needed!

And of course, anyone willing to just read the document and double check the accuracy of the information contained within it are very welcome.

EDIT:

This server is only for those who are interested in adding to the paper that will be published to teach you how to write up a solver, this server is not for learning CFD or tutoring. Please do not ask to enter the server just to learn how to make a solver. Once the paper has been finished I will consider opening it up as a tutoring hub for applying the concepts from the paper to an algorithm.

Hello everyone, a little help and push in the right direction would be appreciated.
I am running a simulation and analyzing bladeless fans. My goal is to have a specified velocity magnitude at a distance measured to be 3 meters away which in this model, is designed to be at the outlet wall at the far bottom. Every time i run the simulation, it abruptly stops at 0.6m as you can see from the plot. I have tried numerous changes and i cant seem to find how to fix this. I changed the analysis from transient to steady thinking maybe am not capturing enough time steps, did not solve the issue. Changed and used different turbulence models also didn't help. Also tried increasing the number of iterations also no avail. Am not an expert, i just began using CFD Ansys 2 months ago. The boundaries i named were the inlet, slow inlet, and outlet, those 3 only. The inlet is set to be inside the airfoil, the slow inlet is the top edge of the surface and outlet is the bottom edge. The slow inlet is applied to simulate air velocity/air flow inside a room and is given a very low value.

Boundary Conditions applied

Inlet Velocity: 5m/s
Slow Inlet Velocity: 0.005 m/s
Pressure Outlet: 0 gauge pressure
Walls set to be stationary and non slip

https://preview.redd.it/01fsr98pc59e1.png?width=2327&format=png&auto=webp&s=977c318a8fef6881ac1e7d3ce967d890da76ea8f

https://preview.redd.it/208zy3jrc59e1.png?width=2323&format=png&auto=webp&s=eb5de34c85c10e8681a56a07ff5ab44434791b10

https://preview.redd.it/8a1uhtfsc59e1.png?width=814&format=png&auto=webp&s=4628490d52c0ce86a24150c7c738dcea3eed850a

https://preview.redd.it/847930wtc59e1.png?width=793&format=png&auto=webp&s=f97ef6b312f5fe630307917fe2ddda66d639d820

Hello all!

This past semester I took a graduate course in CFD. My department specializes in hypersonics and the class taught the numerical side of it (not just how to use Fluent) and we coded up our own algorithms to solve steady state viscous supersonic flow using finite volume and flux vector splitting. There were times that I got stuck and tried googling and I didn't find much help since this is a specialized area. I completed the course and I have a really good understanding of it and have been writing up a paper to help others write their own code because it was really awesome feeling completing the project and I want others to feel the way I did. I have tinkered with Fluent for a school project and I prefer coding up a solver just because it makes me feel like I understand everything that's going on more than using a software and seeing your own code line up with analytical results is extremely satisfying.

I just wanted to see if anyone here would benefit from me continuing to write the paper and eventually posting it. I notice a lot of Fluent questions and wondered if anyone had interest in coding up their own algorithms and understanding how it works. Upvote this if you have any interest, I want a reason to keep writing! It might be a couple weeks before I get it finished.

EDIT:

I'm happy to see so much enthusiasm! As a heads up, writing all my notes and stuff in LateX may take a considerable amount of time so I am not sure when I will be able to post it, but am excited to keep working on it. I hope to get it up over the Christmas break. Also, this is a compressible code but it does not factor in real-gas effects or chemical non-equilibrium, both of which are necessary for hypersonic applications or re-entry. So it is not completed in that sense but you should be able to extend your code to include those effects if you want. I don't know how to do this so I won't be able to guide you through any of that.

Also, I am an undergraduate that took this class (long story, have been in community college and now University for 7 years, so I am taking advance courses to apply to graduate school). I am by no means an expert in this field. I will do my best to describe complicated subjects but I can not guarantee that my explanations will be correct, but the math will be.

I am planning to study FSI. Can someone give me some tips on how to get started? I'm also interested in doing my thesis on aeroelasticity. Thanks jn advance 🥺

First a TL;DR, because you may find I meander or ramble a lot: I'm interested in using CFD software to simulate and generate realistic sounds from 3D models of vocal organs, both human and non-human, as well as fictional alien designs. Is this feasible with current technology?

Here's a question for you. I have had an interest in using this software - or a package like it - to simulate what happens when air (the fluid) goes through and affect vocal organs (could be human ones), using the technique to make all parts of the organs behave the way they should in terms of what materials they are made of, their shapes, densities, how they are all connected, what forces are applied where etc., with the hope to, in the end, actually use the software to generate the resulting sound(s).

I have been told by physicists who study and work with fluid dynamics that this is a monumental task, perhaps even impossible at the stage of CFD as it is.

My hope is, at its most basic that I can formulate for you - to use CFD software to generate, in the way (or the closest possible to it) to how it actually works in real life, human phonetic sounds from human vocal organs, the air (fluid) that we humans use to create our sounds, in all possible configurations that we are capable of doing in rea life.

Look at it like Vocal Tract Lab, or perhaps Pink Trombone, programs in which you can also cause different things, like the tongue, the throat, the mouth and teeth to move into different "configurations." If I could get the other stuff working somehow, and then animate the nasal cavity, the mouth parts, and the throat, to assume the exact "configurations" that they assume in real life when forming specific phonemes, and actually have the software cause those phonemes to come about as a result. That is, I don't actually want to do it the way VTL or PT works, as they use pre-recorded sample sounds. In the case of Vocal Tract Lab, I believe it is a collection of samples, or perhaps it is one or a series of different tones, which are then manipulated strictly by sound-processing software - based on the configurations of the mouth parts presented to you (in the form of a 3D mesh) that you decide yourself by dragging them around with your mouse. Pink Trombone is a 2D version of this same thing, but while Vocal Tract Lab seems to only be able to generate one sound at a time (unless I just need to learn how to use it more, probably likely...) Pink Trombone has a constant audio tone going on, which you can manipulate by moving these kinds of parts around. Even has a "hidden" text to speech system that controls the configurations for you, and you can even get it to say a series of words or phrases, though it comes out as very unnatural, computerized-sounding noises.

But, like I said, this isn't what I would like to do. I have heard before of actual sound generation techniques using CFD, so I was hoping for the ability to do the same. Or at the very least if you, or anyone else, could enlighten me about how far away we might be from something like this. Is "Ansys Sound" not essentially this, actually?

Possible applications of the tech
My ultimate goal or dream with a technology like this would be to be able to apply it to vocal organ systems of animal species other than humans, too, whether we're talking about species of birds, mammalian ape species or feline creatures. Remember when researchers figured out via MRI-powered 3D-scanned models of chimpanzee vocal organs that a chimpanzee can theoretically make all the same phonemes as humans can, going as far as saying the full phrase "Will you marry me?"? Of course they did conclude that they cannot truly do it, but only due to the lack of the necessary brain power that humans possess. But not only would it be a useful tool for researching what exact phonemes (sounds) every species of animal that have vocal organs can theoretically produce (given the necessary brain power, of course), it could also theoretically be used by creators of fiction media.

The fiction application is an extremely niche one, but questions like "What kind of sounds can the vocal organs of a fox/elephant/bird produce?" as well as questions about developing entirely alien vocal organs of their own designs and figuring out what sounds they can realistically produce are common enough in worldbuilding communities on the internet that I am sure worldbuilders would find this stuff immensely interesting and useful. I know that I would personally love to use tech like this to create vocal organ systems for different alien creatures for my own science fiction and fantasy worlds that I have written fiction within. I am particularly interested in creating fiction that is set in the "hard science fiction" genre, or something that is at least somewhat close to being that realm, which is a genre characterized by showcasing science and technology that for the most part (or 100% of the time) adhere fully to known scientific principles. No laser guns or faster-than-light travelling (unless you provide scientifically plausible explanations for how it is possible, with a reasonable but not overused amount of "handwavium".)

It might also be used to simulate the sounds of wind instruments - and I can imagine using it, or at the very least FEA, or somehow a combination of the two - for simulating the sounds of other types of instruments too, including stringed ones, though it would work quite different, with possibly only the resulting sound having to do with fluids, as the sound waves, or "vibrations" (a form of energy, as you know) produced by the moving (vibrating) strings are spreading through the air (a fluid). But now I am getting very off-topic. Sorry.

I've been rambling on for enough time now. So to summarize:
using CFD to create vocal organs and generating sounds with it, not just for human vocal organs but other animals, and even made-up non-human creatures, with the system needing to be able to:

• Account for material properties and densities of vocal organs.
• Simulate airflow through dynamic geometries.
• Generate sound waves based on fluid-structure interaction.

I think that's all, hope I am not forgetting something. So, my question is this: Is it doable yet? If so, how?

For those interested in having a little fun with the two programs I mentioned (they are free):

• VocalTractLab
• Pink Trombone (more information at IMAGINARY's website, and at the GitHub repository)

Hey CFD community,

Starting my journey in CFD has been exciting but also a bit overwhelming. I'm currently learning fluid dynamics, heat transfer, ANSYS Fluent, and dabbling with MATLAB and Python. My goal is to apply for roles as a CFD Application Engineer, but I’m struggling to figure out how much knowledge is enough to feel prepared.

I’ve done some courses on Fluent from Udemy and other online platforms, and I’ve also practiced through some good YouTube channels. Additionally, I’ve completed mini-projects and replicated some basic research papers.

CFD is such a vast field that I often feel underprepared. I’m unsure how much theoretical CFD knowledge I need to have as a fresher. How deep should I dive into the theoretical side versus the practical application?

Does anyone have a structured pathway or checklist for someone starting out? Any advice on preparing for job applications in this field would be greatly appreciated.

Thanks in advance!

TLDR: if you had to run cfd locally on a laptop, what spec would be important (assume no license restraint and can use gpu solver for software like fluent or starccm+)

Hello everyone!

Firstly I'd like to wish everyone a happy holidays and a merry Christmas! I know this post may sound like not CFD related, but it is, please bare with me.

I'm on discord talking to some "tech bros" about what they would like to see at CES, all the while backing up my cfd data I have for the fsae cases and project cases I've run. These files get narly in size (like one case is 100gb, even though they are 7zip"d). One of the bros comment about it saying, you need to upgrade since I'm doing to much on my old laptop. Another asked what sort of hardware I'd need for my work.

So here I am listing out what I do: - Rans and DDES for enteral aero for fsae - aeroacoustic and flow vibration

Having access to many cfd solvers (including fluent and starccm+ along with openfoam) i also talk about how some have gpu solvers and how I ran a 15m cell bicycle aerodynamic case on my old laptop (finished in 9000s wall time for 4 cores on an i7 7700hq, but we usually use servers as memory bandwidth and then cores are important. They say well new laptops coming out at CES one of them should be good for cfd. Which got me thinking,

If we are to run local cfd (Rans, DDES, Les acoustic) without server access for relativitly small to medium size on a laptop (maybe even using gpus) say overnight or in the lab while you work on experiments, what would be the factors to look for in order to maximize performance?

Since all laptops are dual channel, I assume it be whatever has the fastest ram speed and good amount of cores? Maybe a decent nvidia gpu ? Also I believe hybrid cpu are a no go, unless there has been a way to decompose parallel runs so they can use p and e cores efficiently?

Whats everyone's thoughts on this?

Hey CFD community,

Starting my journey in CFD has been exciting but also a bit overwhelming. I'm currently learning fluid dynamics, heat transfer, ANSYS Fluent, and dabbling with MATLAB and Python. My goal is to apply for roles as a CFD Application Engineer, but I’m struggling to figure out how much knowledge is enough to feel prepared.

I’ve done some courses on Fluent from Udemy and other online platforms, and I’ve also practiced through some good YouTube channels. Additionally, I’ve completed mini-projects and replicated some basic research papers.

CFD is such a vast field that I often feel underprepared. I’m unsure how much theoretical CFD knowledge I need to have as a fresher. How deep should I dive into the theoretical side versus the practical application?

Does anyone have a structured pathway or checklist for someone starting out? Any advice on preparing for job applications in this field would be greatly appreciated.

Thanks in advance!

Hey guys I have been doing pseudo transient simulation for external flow around a body. I used to use automatic pseudo transient settings. Now the thing is the simulation doesn't converge. I changed the pseudo transient settings to user defined. And gave a time step size of .05s. I would also like to mention that my automatic pseudo transient time step size was .9s . Now is it a problem to use .05s as a time step size if I wait let's say may be 200 iteration after convergence to be sure about the convergence.

I’ve been taught that using 0.3% turbulent intensity for external error is quite common. I’m using 0.3% for a 1m airfoil. If I’m scaling up the airfoil to 3m, then I need to increase the turbulent intensity right, because the intensity will die down due to diffusion by the time it reaches the air foil? My question is by how much should I increase my turbulent intensity? Before scaling up, the distance from the inlet to the air foil is 12.5 m.

Hey, I am working on a 3D CFD problem and when I try to add an inflation layer, it doesn't let me select the body but only the faces. With inflation I can only do

Body as the main geometry and faces as the boundary

OR

Faces as the main geometry and edges as the boundary.

I want to do the first one but for some reason, when I try to put the body as input, it changes it into faces. Does anyone know how to fix this?

Adding an image below.

https://preview.redd.it/xl7a2qojnq8e1.png?width=556&format=png&auto=webp&s=fed001b1526048ad059d76f6b2cdbf663756ae39

Hello, I'm planning for my masters in Fall 2025, particularly in programmes that have a fluid mechanics track with CFD courses etc etc. I've applied to KTH (Engineering Mechanics programme), Chalmers (Applied Mechanics programme) and TU Denmark (Mechanical Engineering programme).

Now I've gotten an admit from TU Denmark and as for the other two I'll know in the last week of March. I have until May 1st to accept/decline the admit from TU Denmark.

So now it comes down to which among the three would be the best choice. I'm not too sure of my chances of getting into KTH but in case i do, i think I'll pick that. But if it comes down to Chalmers and TU Denmark I'm not sure which one would be the better pick. I'd love to hear from y'all if you have any suggestions or experiences about the two. They both have a fluid mechanics track with pretty similar course structures.

Thanks in advance!

https://preview.redd.it/t96bf7y67k8e1.png?width=887&format=png&auto=webp&s=0db69e04f530254b504a5a7cb31b1defdc5f4288

Hi everybody,
I'm currently simulating the flow of air over two staggered pipe at fixed T (geometry in picture) with STAR-CCM. I'm solving the problem with k-omega SST, since I'm interesting in the pressure drop and heat exchange, so i want to accurately solve the phenomenon at the wall, but at the same time I do not know completely the inlet condition (hence the SST choice). Wall treatment low y+. I noticed that with a segregated flow approach the solution diverge (or, at least, oscillates), while with a coupled solver the solution is ok with low residual and convergence of main quantities. I could go with coupled without posing any question, but I would like to know why. Anyone has some ideas? Thank you very much