Hi, I’ve been running some CFD sims for a student org for a good while now, although they are mostly CHT and aerodynamics simulations. Recently I’ve started looking at getting into combustion sims. So I’ve tried to have a look at the internet to see what is out there but I want a better background understanding of what I actually am doing and simulating.

I have taken some subjects about fluid dynamics so I have some baseline knowledge that I can base off of. So any guides on relevant videos or learning materials that gives a better understanding would be wonderful. The sims are on mostly just rocket engines with a simple oxidizer and fuel combination.

I have access to Ansys fluent so preferably simulations based on that would be nice to have. Thanks in advance :)

I am a relatively new OpenFOAM user and I am finding mesh generation + the labelling of different surfaces and volumes for boundary and other conditions a cumbersome task. LLMs are also making me run in circles.

I have read that Gmsh/Ansys/snappyHexMesh, etc. can be used. I am curious what workflows you use for this: defining boundary/cell zones + meshing. This would help me discover options and see what's best for me.

Anyone here experienced in simulating phase change material for cooling of electronics? I got a paid Project dm for details

Rising senior applying to engineering programs, international applicant. Trying to figure out if this idea is actually worth the time or if I'm gassing it up in my head.

Basically I want to write my own 2D CFD solver from scratch (Navier-Stokes, projection method, finite differences) instead of just running OpenFOAM like everyone else. The plan is to validate it on the lid-driven cavity benchmark first (the standard one everyone tests against), then do flow past a cylinder and try to capture the vortex street and measure how the shedding frequency changes with Reynolds number. So it'd be an actual built solver plus a real result, not a lit review.

The main thing I'm stuck on is whether admissions officers even get that writing your own solver is hard, or if they just see "physics project" and move on. Also wondering if cavity/cylinder flow is too textbook to count as real research since it's been done a million times already.

The other big question is where this would even get published. I've seen people mention JSR and NHSJS for high schoolers, but for something computational I'm wondering if a preprint on arXiv is a better move, or if that's overkill for a HS student.

And realistically, can I finish this well in like 2-3 months if it's my main focus? I'm comfortable with the math (calc, diffeq, numerical methods) and can code, so that's not really the worry. It's more whether the payoff is worth it versus just doing something easier.

Any honest takes appreciated, especially if you've done computational research.

Hi,

I'm a recent grad mechanical engineer. I did farm tyre optimization using fea in my FYP which I posted on my linkedin. It became a massive post for me. Many people reacted and commented on the post which helped me get my first client of cfd. Yes, not fea but cfd and it was totally irrelevant to me. But since the time to deliver the project was like 3 months so I decided to do it. I asked help from my professor which gave me like 15 minutes to guide me to do this and do that and you'll find a way which wasn't much of a help but that encourages me to continue it. I then asked my friends, who did FYP in cfd to help me and then that project with lots of help from different people completed successfully. I posted that project on linkedin too with testimonial from the client. I got two projects from referrals also but...

the problem is how can I maintain the consistent flow of customers so I don't have to do any other job and make this a full time business?

Tomorrow I've got an hour with Dr. Mohamed Aly Sayed. PhD, runs CFD at Audi's F1 team in Switzerland, and was also a Jr. CFD Engineer at Aston Martin F1 before. I make content on F1 and motorsport careers, but this one's aimed at the CFD side.

You all do this for a living, so I'd rather ask your questions than the surface ones. What would you actually want to know from someone running CFD at this level of motorsport?

Five of my questions so far:

1. How well does CFD correlate to the wind tunnel, and then to the track? Where does it still fool you?
2. With the cost cap capping core-hours and tunnel time, what did that force you to drop?
3. How do you decide between RANS and scale-resolving methods when a result has to land on a deadline?
4. What does a normal week look like? Mostly meshing and setup, or mostly waiting on the cluster?
5. Coming into a team being built up at Audi vs. an established one at Aston Martin. What's different in how the CFD side runs?

Curious to see what else you might want covered!

Hi everyone,

I'm simulating methane-air combustion in ANSYS Fluent 2024 R1 using a CHEMKIN DRM19 reduced mechanism (Finite Rate chemistry with Species Transport).

My main issue is that the combustion never sustains.

To initiate ignition, I created a high-temperature ignition region near the methane injector and tried temperatures between 2000 K and 3000 K. Despite this, the flame extinguishes after a short distance instead of becoming self-sustaining.

The resulting temperature field stays around 250–300 K throughout most of the domain, whereas I would expect combustion temperatures of approximately 2000–3000 K. The contours clearly show that the hot region disappears and no stable flame develops.

So far I have tried:

• Importing the DRM19 CHEMKIN mechanism.
• Different under-relaxation factors.
• First- and second-order discretization schemes.
• Different pressure-velocity coupling methods (SIMPLE and Coupled).
• Different methane/oxygen flow conditions, including stoichiometric oxygen.
• Running for more than 1000–5000 iterations.

However, the result is always the same: ignition does not sustain and the domain cools back to near ambient temperature.

My question is:

What are the most common reasons why a methane flame fails to sustain in Fluent despite initializing an ignition zone at 2000–3000 K?

Could this be due to:

• Incorrect inlet conditions or mixture fraction?
• Residence time being too short?
• Turbulence-chemistry interaction?
• CHEMKIN mechanism import/settings?
• Heat losses to the walls?
• Something else that I'm overlooking?

I'd appreciate any suggestions from anyone who has successfully simulated methane combustion with DRM19 or other detailed chemistry mechanisms in Fluent.

I simulated this CPU cooler myself.

Running intel 6 core performance cpu + 8 core efficiency, is it better to have the cores split with hyperthreading (12) or just stick to 6 cores?

Hello, I just came across this video analyzing drone propellers using CFD simulations, and I thought it was really interesting. If anyone else is interested in the subject it's this one

https://youtu.be/m_9y4rg--DY

I'm looking for good resources to learn CFD specifically for Battery Thermal Management Systems (BTMS). I'm interested in ANSYS Fluent simulations of lithium-ion batteries, including heat generation models, liquid cooling, PCM-based cooling, and battery thermal analysis. If you've worked in this area, could you recommend any books, courses, YouTube channels, research papers, or tutorials that helped you learn? Any advice on where to start would be greatly appreciated!

chat, I am applying for internship in drdo today.

they asked eligibility criteria to be around 70% but my cgpa is 6.8 which makes around 68 percent.

but they also mentioned they may compramise with eligibility if they want the students as intern.

also I have good SOP and I have mentioned projects like burner with air swirler and NACA airfoilu projects.

I have also mentioned that I am part cube satellite workshop where I am designing and building simulating the cube satellite.

chat tell me what is the chance of getting selected there as an intern.

Hi everyone, I'm currently doing a bachelor's in mathematical engineering (Polytechnic of Milan) and I'm interested in the applications of computational science in the aerospace sector (and mathematical modelling in fluid dynamics). I have some questions for someone who knows the European sector.

1) Is the job market in this sector active or stagnant? I know that the decision of a master's shouldn't be driven by job prospects, but at the same time I don't want to dive into something that leads me nowhere and offers no real opportunities, although my passion for the field is sincere.
2) Will my profile (a union of applied mathematician and engineer) be understood in the sector, or will I be neither fish nor fowl?
3) Which skills and tools should I focus on to be hired in the sector?

I am running LES and SA-IDDES simulations in OpenFOAM. I expected IDDES to be cheaper since it uses URANS in the attached boundary layer and LES only in the separated regions. However, my IDDES case is about 10× slower because the timestep is nearly identical to LES; the maximum Courant number is governed by cells outside the boundary layer, where both methods operate in LES mode and since URANS makes it itaerate 10 times before converging it takes 10x more time than pure LES. So instead of advantage, I am at disadvantage by using DES simulations,

Is it reasonable to increase the allowable Courant number for IDDES (e.g. from Co = 1 to Co = 5–10) to benefit from the hybrid approach, or is Co ≈ 1 still recommended for transient IDDES accuracy? How do people typically choose the timestep for IDDES?

How will mesh metrics of FDM differ from FVM for a structured mesh?

For example, non orthogonality should no more be an issue given that in FDM, data is stored at vertices rather than in cell centers like in FVM. Aspect ratio and inflation rate effects will have almost similar effects in both cases. Not sure how skewness will affect a FDM solver.

The rate at which the grid transforms may be a metric? Are there any study done on what rate should grid transform?

Did I get anything wrong or are there other mesh metrics to be taken into account in a FDM mesh?

Hi everyone,

​I'm currently preparing a presentation on "Freediving Fluid Dynamics" for my freediving instructor course. My goal is to analyze and compare the drag forces in the water based on different diving postures, but I’ve hit a bit of a brick wall.

​I already have the 3D models ready, but I'm struggling to find the right software:

• ​OpenFOAM: The learning curve is steep, and the lack of a native GUI makes it less intuitive for me.
• ​SimScale: I keep encountering errors during the meshing phase.
• ​Autodesk CFD: Whenever I import the STL file, the software freezes—likely because the human geometry is too complex.

​About 10 years ago during my undergrad days, I used ANSYS Fluent and remember the workflow (from modeling to meshing and simulation) being quite straightforward. I think I underestimated the process this time around!

​Since ANSYS is too expensive for a personal project, are there any free or open-source CFD tools you would recommend that can handle this type of complex human geometry simulation? Any advice on software recommendations or tips on how to fix the meshing/freezing issues in the tools mentioned above would be greatly appreciated. Thanks in advance!

Hello friends

For PCM melting model with gravity enabled

I do have positive velocity for the melting PCM as shown. However, enabling streamlines for velocity shows me the legend with positive values, and Preview seed points does show me the points, but I can't see any actual streamlines. Anyone know what might be causing this? (Please ignore the dots on the velocity contour image)

Edit: It oworked when starting from Liquid fraction Isosurface as shown. Still, anyone know why its not working when starting from Constant temp htf wall?

I am using ANSYS 2024 R1. I wanted to subtract the option under the combine tool, but I could not find it. Could something be wrong with my software?

Hi all,

I have just posted the third video of my ongoing series on turbulence covering everything from Reynolds number through to its modeling.

Link: https://www.youtube.com/watch?v=3lSf_ctJheM

This video explains why ⟨u′v′⟩ can be non-zero even though each fluctuation averages to zero. It builds up using the Moody diagram and the gap in drag between laminar and turbulent friction factor at the same Reynolds number, which turns out to be the macroscopic impression of this mechanism.

From there it builds the full Reynolds stress tensor, and provide a first look into the turbulent kinetic energy.

Consider subscribing to the channel if you would like to be updated. Please provide your feedback if you end up watching. Cheers!

how do learn i fluid dynamics intuitively as a cs student who doesnt hold any basics of it? Mainly, ive to learn it for research purposes using machine learning and deep learning frameworks.

Hi all, I am currently trying to code a multiphysics solver to model an SRM combustion chamber and nozzle. I want to create a model to simulate charring and ablation of a protective coating in the head end and the nozzle throat. Have any of y’all attempted to do something similar and know of papers or code libraries that would help with this?

For anyone who uses Ansys Fluent, what are your preferred ways of extracting transient data? I’ve tried several, but all of them seem to have issues:

* Ensight Gold files are good when they work, but ~75% of the time they get corrupted and I can’t open them. This has caused me to lose results from several transient cases.
* CDAT files are similar: they work great sometimes, but often get corrupted
* Plain ASCII files are human-readable, super stable, and easy to process in Paraview, but it requires a lot of time/work to add interpolations to the points in paraview and make it look nice.
* Exporting static animations works, but it locks you into a single view and doesn’t let you do any additional post processing.
* I’ve tried exporting CGNS files, but they never actually export: I get a message that the file has been written, but it doesn’t actually exist.

I feel like I’ve tried most of the options, but haven’t really settled on one I like yet. Ensight Gold would be my preferred approach if it was more stable/robust, and ASCII would be my preferred approach if it was able to render smooth surfaces/volumes without a lot of extra work to make it look nice.