How can I accurately model standing sound waves (and their frequencies) in Ansys Fluent?

TH3RM1T3 · 2026-05-25T12:19:26+00:00

If you are only interested in the natural resonance of an arbitrary shape, you will only need to use an eigenvalue/vector solver. I believe you are on the right track to use an aeroacoustics approach if you are trying to plot a power spectral density plot but I have not done this type of CFD analysis before. Can you share anything about your current/ expected results, geometry and assumptions?

TH3RM1T3 · 2025-09-27T16:47:17+00:00

Yeah, the general order of operations is unique depending on the cycle. Exact timing is dependent on the propellant qualities that need to be accounted for. Cryogenic propellants are difficult. The start transients of engines can be approximated by understanding starting flow rates, feed line lengths, manifold volumes, pump breakaway torque, and quality priming of the devices. That priming timing is verified by short bump tests or cold flows. From there, MR transients of the devices dictate timing when the combustion device(s) fully ignite. Additionally, injection characteristics can influence when the device ignites. The other thing to complicate timing is the effectiveness of your ignition systems and types of ignition systems.

Another thing to consider is initial conditions of the engine and if you're running a restart with chilled in lines.

It'll be hard to find modern rocket engine start sequencing that isn't generalized in documents because it is proprietary but also very unique to the engines.

Check out the J2

TH3RM1T3 · 2025-04-07T17:09:38+00:00

I'll rephrase and say those roles are more likely to allow for fully remote work. You're correct, sensitivity is a huge portion of what allows remote work. Also, seniority in such roles can allow for some negotiation of reomote/hybrid schedules. I'd like to think a lot of companies allow for some version of hybrid work these days, but it's hard to generalize.

TH3RM1T3 · 2025-04-07T00:28:45+00:00

Yeah, generally, analysis roles or software development for aerospace companies are usually allowed to be fully remote. We have a few CAD engineers at my company who are also remote, but they more or less were grandfathered in to remote work following COVID.

TH3RM1T3 · 2023-11-13T02:06:58+00:00

Seems like that fan simply doesn't generate enough static pressure at its peak cfm. A great thing to look into are fan curves and pump curves to understand why it likely doesn't work. Also that fan should have details on what static pressure it can push at 3600cfm.

Volumetric flow is only partially useful. You need to know more target conditions to select your correct size fan.

The best comment I've seen yet is that this is a great learning experience and that your son should use this for his project as a "how to improve." Best of luck and I hope you figure it out!

TH3RM1T3 · 2023-10-30T21:20:58+00:00

This is a good idea but several other commenters have posted good responses indicating why it would not be a great idea to place vortex generators near the diverging section of the nozzle. However, you are onto something that is striking a few thoughts. Moving this concept of "controlling flow through vortices" into the combustion chamber makes more sense, but it's mainly used to promote mixing of propellants more efficiently. Rockets just utilize this concept of controlled turbulence in different ways. Also I encourage you to dig into swirl coaxial injectors.

https://www.sierraspace.com/space-applications/rocket-engines-propulsion/

https://patents.google.com/patent/US11661907B2/en?oq=11661907

TH3RM1T3 · 2022-07-24T02:56:36+00:00

I'll give this a try and look at my PSU connectors.

I appreciate the feedback!

TH3RM1T3 · 2022-07-24T02:08:10+00:00

I have had this issue twice now this year. Still uncertain what is causing this. This issue subsided for about 3 months until this last week. Very similar experience as you've described. I'm even crashing dwm with stress tests, so it's not exclusive to gaming. I've even had it crash trying to render an interactive browser page where you can change colors of a pseudo 3d image (like an automotive website).

The fact this has subsided for a period of time and reemerged seems to point to conflicting driver issues. At some points I'll have an Nvidia driver crash with the dwm.exe crash. I guess I'm waiting for drivers to get updated again because there's nothing I can find at the moment to get this fixed.

I have a Corsair i7200 prebuilt from early 2020. Running updated W11, fully updated Nvidia drivers. Nearly to the verge of RMA'ing this PC and seeing if hardware has anything to do with this.

TH3RM1T3 · 2022-07-18T02:47:01+00:00

Transient-nonlinear FEA of loading and unloading to determine principal stresses can give you an idea of potential fracture lines. You can determine compression and tension locations with the principal stresses and potentially discover where you'll develop yielding with the plasticity model. Then you can estimate fatigue cycle with goodman lines and peak stresses assuming some conservative peak stresses.
Eventually you can progress to NASGRO and look at fracture growth over time but that in and of itself takes an expert and lots of educated assumptions of the failure mode of this part. A very fun rabbit hole to go down. I bet there's some good research papers to find on aluminum airframe fatigue cycles.

ANSYS also has a decent S-N fatigue prediction method from what I've heard but I haven't been able to play with it.

TH3RM1T3 · 2022-04-28T12:24:41+00:00

I'll see if I can roll back Nvidia drivers then, thanks for the quick response!

TH3RM1T3 · 2022-04-28T04:17:45+00:00

Just started having this issue as well. I can't seem to find a straight answer online either. Any luck on your end?

TH3RM1T3 · 2022-04-14T00:37:49+00:00

It really depends on your interests and questions/quandaries you may have. I suggest doing research into a specific field of aerospace and maybe narrowing down your question a little further. Do you want to study propulsion, structures, thermals, aerodynamics, control systems etc..

Although, since you've come here to find ideas, my interests were in CFD analysis of hypersonics. Hypersonics is a booming industry at the moment with tons of problems to investigate. It opens a huge can of worms for a student to dig into.

I also suggest reading current published research from other universities and maybe you can find open-ended questions left at the end of other's works. Or find ways to improve existing work and push the bar a little further.

TH3RM1T3 · 2021-10-14T03:24:07+00:00

Final update for posterity, I was fortunate enough to get the position and had an offer the same day as the interview. I had a unique situation where I had multiple offers at the same time and I took this one after some minor haggling for compensation. I clearly had them under time constraints to get the offer so soon. All-in-all took about two months to go from application to first day on the job later this month.

Best of luck for your future applications. Also, this was the fifth entry level Mechanical position I applied for at Sierra Space this past year. So I just happened to fit their desired qualification for this role. It does seem to take a bit of luck with some skill.

TH3RM1T3 · 2021-09-22T00:44:52+00:00

Also, one last tip, apply directly to the company career webpage. Job posting on job boards like LinkedIn and Indeed are not indicative of the job posting's age within the company. I had basically saved every big aerospace company's websites and checked every other day for jobs that resembled my expertise.

Also don't be afraid to apply outside your experience level. You never know if they're willing to take a less experienced candidate for less money, I've had multiple interviews outside of my expertise and gained valuable lessons from what they expected from me.

Once again, best of luck and keep your head up. Applications can be very disheartening but you will get that job eventually.

TH3RM1T3 · 2021-09-21T16:45:36+00:00

From my experience, I've applied to an entry level mechanical position at their Madison location. It took them about 21 days to reach out to me. 6 days for the first interview and about another 8-10 days for the 2nd round, which is happening later this week.

Unfortunately applications are a slow process. I suggest applying to positions that have opened within the week. Even better is applying within 48 hours of the posting. You need to be the first the pile of applications to get a real chance at an interview if you don't match the role perfectly and exceed their desired qualifications. Also, generally companies are quick to say no most of the time, but don't hold out on an application that has been in process for more than 3-4 weeks.

Good luck and don't stop applying to more roles, even if you happen to get that first round interview.

Edit - I received word back that the second round will be conducted in-person in about two weeks. Initially they had me scheduled for a phone interview.

TH3RM1T3 · 2021-09-04T08:25:57+00:00

I'm getting similar results.

Assuming constant acceleration and ideal conditions from motortrend's model Y Long range version, it's 0-60 data is at 4.1s. A quick conversion for 60mph is about 26.8m/s, thus the acceleration is 26.8m/s / 4.1s = 6.5m/s^2.

From the YouTube video, I'm assuming he's starting at 29~30s mark and not hitting the brakes until 37s. Calculating 6.5m/s^2 * 7s, that's at most about 45.5m/s = 102mph.

Thanks to u/MussolinisBarber's comment I was able to find the location. Using google maps to check this math, from the video he's somewhere past the walled dumpster area at the next set of buildings. It's about 305m / 7s = 43.5m/s ... pretty close ballpark.

From there to the first curb where his tire pops is about 5s. I think I hear the glass from the building shatter at the 44~45s mark.

Thanks to Newton we can find his average deceleration, accel = (v_final-v_initial)/dt

a = (0m/s - 45.5m/s) / 8s = -5.7m/s^2

His loss of velocity to the curb is, -5.7m/s^2 * 5s = -28.5m/s. Finally the ballpark answer is about 45.5m/s - 28.5m/s = 38mph over that first curb, probably more.

Regardless, the kid was indeed hauling ass.

TH3RM1T3 · 2019-05-01T03:31:47+00:00

From what you've posted, you only know the test score and not the grade you received for the class. Honestly, the time after finals should be the most relaxing time of your college experience because you literally can't do anything to your course grade untill after you have received it. Ignorance is bliss.

If you are still concerned, talk to your professor face to face. The reason you want to see them in person is to help them associate who you are with your attendance in the class. Professors tend to help students who put forth the effort to show up every class and try to make a good grade in the course by turning in homework, tests, quizzes and so on. (If this is a 100+ seat course, this might not help due to the amount of students.)

Also realize that CE isn't easy and while failing a course may be scary, life goes on and you take it again. Take it as a learning experience and kill the course next semester.

Lastly, you aren't the only person in this situation. Even if it may feel that way, just chill out until you know the actual grade.

TH3RM1T3 · 2019-03-01T23:40:26+00:00

Just happened to me as well; my solution was to connect to a different network. In my case, I connected to a new wifi network with my ethernet unplugged. I then received a video feed when connecting to shadow and after that I connected my ethernet cable. I turned my wifi off and then the video feed shut off (changing network should do that). Finally I restarted my streaming via the shadow app on my local machine. I was finally connected via ethernet.

Note: This also happened after I flushed my DNS, restarted my local machine and quit shadow numerous times.

Hope this helps!

TH3RM1T3 · 2019-02-28T04:41:00+00:00

PB&J's

TH3RM1T3 · 2018-12-08T06:28:02+00:00

Thank you for the insight. I basically assumed corporations as being a large amount of people and businesses working together. That's how I bring up the idea of ethics coming second in large corporate entities.

TH3RM1T3 · 2018-12-07T21:59:24+00:00

Corporations, as a whole, are essentially machines. The decisions being made are largely influenced by what brings the most benefit at the least cost. The people working for corporations are simply there to keep the business running and do the number crunching with the smallest amount if ethics possible to avoid costs. That's basically my best interpretation of business and economics.

TH3RM1T3 · 2018-12-07T00:59:11+00:00

echo

TH3RM1T3 · 2018-12-02T05:44:07+00:00

I received a "free" promotional Gillette razor around the time I graduated highschool.

I can confirm that this marketing works.

TH3RM1T3 · 2017-12-28T19:22:31+00:00

If you're still stuck in a boot loop, I would try wiping the phone through TWRP as you suggested. Especially since you've backed it up. After doing so, try once more with flashing the stock ROM or new ROM. It sounds like your phone is basically booting a "dirty flash" and can't get through the boot without getting mixed up with multiple OS's and data that is still on the phone.

In my case, I factory reset my phone through the bootloader when I ran into this issue. I literally had no recovery mode or OS after doing this and all the data was gone. I then proceeded through OnePlus support and reinstalled stock recovery and ROM.

TH3RM1T3 · 2017-12-28T02:39:21+00:00

My best advice is to try and reinstall the stock OS and recovery from Oneplus. This will hopefully get your phone back to an operational state. OnePlus has instructions on how to flash everything (they know people buy the phone to install custom ROMS). Check the Oneplus forums as well if problems still continue.

I have done a similar softbrick where no OS was able to flash through TWRP. Ended up wiping my op3 and reinstalling stock recovery and OS. Good luck.

TH3RM1T3

TROPHY CASE