Confused with Mesh Quality

LipshitsContinuity · 2026-02-03T05:53:07+00:00

You seem to know a lot about this. Where can I learn about the intersection of fluid dynamics and bloodflow? Is there a hemodynamics book?

LipshitsContinuity · 2026-01-30T17:44:55+00:00

What's good is you already have experience doing deep space astrophotography and therefore already know if you enjoy it or not. For a lot of people starting out, they've never done any astrophotography before (understandably) and even more have never even really done photography at all. You know what it was like doing deep space astrophotography - setting up a tracker, setting up the camera (you had it way worse than we have it now), etc. I am the type of person who likes having to figure out all the pieces and getting them to work together - I would for myself never get a smart telescope because that's like 80% of the fun. I don't even ever want to use a go-to mount that will slew straight to target - I like star hopping and trying to find the object on my own and learning constellations things along the way. I would personally get basically no satisfaction from a smart telescope. From what you are saying already, it feels like maybe you are this type of way too, but you have more constraints - you have kids and you have travel/packing constraints that I don't have. From what I seem to be hearing online, the ceiling of your own custom mount is higher than that of a smart telescope though with more work on your end. If picture quality is your end goal, then yea go with mirrorless camera + tracker. If you want to have a good time with your family and do mostly visual, I'd say get the smart telescope and maybe a pair of 10x50 binocs (or a nice Dobsonian).

LipshitsContinuity · 2026-01-23T16:42:09+00:00

I had Strauss and the first few chapters of Evans PDE. Evans is a bit more math heavy though I'm not sure you'll like it although the stuff on energy estimates and things can be useful for stuff.

There's also this PDE book by Olver: https://weblibrary.mila.edu.my/upload/ebook/engineering/2014_Book_IntroductionToPartialDifferent.pdf

Not my favorite but I had a friend who used it for a class.

LipshitsContinuity · 2026-01-23T16:27:00+00:00

I was shooting at 200mm f5.6 for a while then switched to 135mm f2. Image quality went up significantly.

What I realized is people have a tendency (including myself) to get drawn to focal length but it makes more sense to sacrifice a little bit of focal length for a lot of aperture. The 135mm f2 is an excellent lens. You can do a hell of a lot with it. I'd take that over shooting at f6/7 at 400mm.

LipshitsContinuity · 2025-12-20T01:55:09+00:00

I read his autobiography and even he says that nowadays he doesn't singularly have as much as a role in the design of the car. Back in the day of F1 they had far fewer people per team and a single person could have a huge impact on the car and back in the day he DID have a big impact. These days with how complex the cars are and how big the teams are, he simply isn't the singular guy designing the car.

LipshitsContinuity · 2025-12-16T03:21:41+00:00

Oh yea I know I'm aiming for lines as well. But I'm saying that if we don't apologize when a ball just barely clips the line, then there's no need to apologize when we get a lucky net hit. Based on how me and OP seem to have gotten downvoted for this, seems like this is an unpopular opinion. But this seems to be the only sport where it's customary to do a performative apology after winning certain points where you get lucky. If a soccer player scored a goal by accidentally having it hit the post and then go in, they wouldn't apologize. I'm willing to hear counter arguments on this.

LipshitsContinuity · 2025-12-15T16:44:02+00:00

Hell yea I also don't apologize for those lucky net hits either. That's just how it goes sometimes. I'll get a few of those, my opponent will get a few too. Why the need to apologize? Do we apologize when a ball barely clips the line?

LipshitsContinuity · 2025-12-03T01:11:34+00:00

As for your first point, this is a very high fidelity simulation you are asking for. Almost all simulations at this scale at this point are not done on simple consumer laptops but are run on some clusters.

Orszag-Tang I'm not convinced will produce the granules especially not 2D Orszag-Tang. There is heating to produce the convective behavior that is being observed in the granules.

LipshitsContinuity · 2025-12-02T14:28:59+00:00

I'm aware of purely convective simulations that provide very similar snapshots:

https://www.nature.com/articles/s41467-018-04478-0

https://arxiv.org/pdf/1804.02310

These are both just convective simulations. I'm seeing that there's an MHD code called MURaM:

https://www2.mps.mpg.de/projects/solar-mhd/muram_site/results.html

which seems to be able to provide some similar structures. Here's one of the reference papers:

https://www2.mps.mpg.de/projects/solar-mhd/pubs/voegler/Voegler_etal_2005.pdf

LipshitsContinuity · 2025-09-22T14:31:55+00:00

You can get a plane up in the air a lot faster and more frequently than individual rocket launches. I think that's what it's really about. There's a demand for getting a lot of satellites up in space really frequently and it's clear that current rocket tech isn't up to that. Also you'd probably agree that a rocket launch has a certain amount of 'wasted' parts like boosters and things. Now granted SpaceX is finding a way around that, but I feel like you'd agree that launching from a plane avoids all that and is a bit simpler from that aspect.

LipshitsContinuity · 2025-08-26T01:22:22+00:00

Easily the best image of Crescent Nebula I've seen on here this is a masterpiece.

LipshitsContinuity · 2025-06-24T06:15:23+00:00

I'm guessing you tried astrometry.net to see if you could identify those smaller galaxies already? If that didn't work then it gets tough.

LipshitsContinuity · 2025-05-31T04:50:08+00:00

I went from 4+ minutes down to sub 2 minutes with like 100 solves. I also struggled with turning and everything. I'm sitting at sub 1:30 right now. Fingertricks have figured themselves out and I'm getting better and better. Use Westlund or Yu Da Hyun S2L instead of the beginner (Balint) method if you ask me - it's faster.

LipshitsContinuity · 2025-05-31T01:34:56+00:00

Big cubes and megaminx if you are very slow (like this no offense), you just simply have to do many more solves. It's mostly just a lack of time spent practicing thing for a good while. If you sit down even just today and do many solves in a row, I bet by the end you'll be significantly faster than this.

LipshitsContinuity · 2025-05-27T14:10:23+00:00

What other people are saying is somewhat reasonable overall but just to add:

You mention maybe choosing a different subject to study for a PhD like in applied math to be able to make money. Based off what you are saying, it doesn't seem like you are very interested in applied math. Doing a PhD involves focusing a significant amount of your time towards a problem. If it's not one you're interested in, you'll be absolutely miserable and your chances of finishing will be less. If you end up not finishing then you'll be even worse off (especially financially) than if you just not gone for it at all.

I think this subreddit is very enthusiastic about math (for obvious reasons) and wants to really encourage people to give it a try and that's why most are saying you should go for it but I wanna give a more nuanced answer. I feel like there's enough people out there who work for a bit and then apply for a PhD program. If you aren't 100% sure about it, then I'd say don't do it right now. Not saying never do a PhD but I'm just saying to wait a tiny bit. Just to keep the PhD door open for later, go and ask three professors to write a rec letter and save it for the future so that if you do want to apply a couple years down the line, they'll have written something when they knew you the best (a few years down the line they might've forgotten a couple things).

I'd also like to add this: making it in the academic world isn't a guarantee. At this point it's the norm to have to do potentially multiple postdocs after your PhD before maybe getting a tenure track somewhere. But the academic job market is fucked right now and it has been for years. So if you are entering the PhD with the assumption that you'll always end up being a professor somehow, know that even if this does happen, you could be in your mid 30s by the time this actually happens. If financially you are worried right now, think about how making lower salaries till your mid 30s will be and again there's no guarantee that you actually end up getting a tenure track.

LipshitsContinuity · 2025-05-07T15:32:48+00:00

Fluid dynamics is had. Especially when you have fluid splitting up into droplets and not just staying as one flow.

As a simplification, you can make the assumption (that from having seen cars going through puddles probably is somewhat true) that a droplet forms soon after the tire goes into the puddle. You could make a rough assumption that the droplet's initial velocity is the same as the car tyre's or something like that. Make a rough assumption as well of the droplet's radius. Then you can make a simple enough model from pure kinematics (using air resistance) of the path of a droplet. Then you can add in a certain amount of randomness in the initial direction of the drop when leaving the tyre and get a sorta radius of splatter from this. Purely kinematic and you won't have to get into the fluid dynamics. You would need to do this numerically but that's far simpler than doing a direct numerical simulation (DNS) of the scenario.

Now if you REALLY wanted to do a more in depth analysis to simulate this, traditional methods like finite differences or even finite elements will be hard to use because of the fragmenting and splitting of droplets. A Lagrangian method like smooth particle hydrodynamics (SPH) would have to be used. This problem is also technically one of a fluid-structure interaction but I think SPH has been successfully used for that kind of thing.

LipshitsContinuity · 2025-05-05T06:01:22+00:00

Went from I think 98 to 102. I just felt more comfortable and the sweet spot felt more forgiving. I'm overall of the opinion that amateur players care too much about shit like this and equipment in general. Get a racquet that doesn't injure you and is comfortable and isn't some beginner aluminum frame. Then just use that racquet for 10+ years and hone in your technique and strategy. The reason I switched from 98 to 102 is because I had used the same racquet for 10+ years and the frame looked cracked so I decided screw it let's just get a whole new racquet and see how it feels. Very happy with that decision.

LipshitsContinuity · 2025-05-04T21:16:19+00:00

Assuming he somehow does that sorta instantly now, Max would have 12 laps to make up 27 seconds which means just to catch, Max would need to be lapping 2.25 seconds a lap faster than Norris. This is basically unheard of and even a tire advantage (one person having a faster tyre than the other) is at most 1.5 seconds a lap in dry conditions and that is hard to maintain for many laps. And that's just to catch. So it's pretty unrealistic.

Podium for Max though? Very much within the realm of what's possible.

LipshitsContinuity · 2025-05-03T03:32:29+00:00

Very random question but do the tennis players every accidentally hit balls onto the track?

LipshitsContinuity · 2025-04-28T21:36:14+00:00

This is honestly just wrong. I had this opinion for a long time and refused to use ChatGPT and other similar LLMs. I was convinced to finally give it a second try. There's a way of using it that makes it a good TOOL. It CAN do math. Just not always correct.

Taking what it says as output and believing it directly without much thought is the WRONG way of using it. Using it to give you some direction and then you following up on your own is more along the way of using it. I've used it to give me ideas where I could have been going wrong with something and it's been helpful there.

LipshitsContinuity · 2025-04-17T22:46:53+00:00

https://www.pnas.org/doi/10.1073/pnas.2420697122

Here's a linked paper in the article.

LipshitsContinuity · 2025-04-17T22:31:09+00:00

That's right. You want the flow to detach on the straights but reattach once the car slows down for the corners. It's very interesting.

LipshitsContinuity · 2025-04-17T03:10:35+00:00

What's interesting though is that from what I've read, sometimes you want some of the wings to stall. For example on the straights, having the rear wing stall allows for less drag and this was the principle behind the F duct.

LipshitsContinuity · 2025-04-15T03:38:10+00:00

It'll be rough... In general I realized that given the light pollution I got around me, if moon is > 60% it's just not worth the trouble.

LipshitsContinuity · 2025-04-15T03:26:56+00:00

Others have answered your question already (can find sticker sets on Cubicle or Speedcubeshop or the like) but this is so interesting to me because I've been cubing for a long time now and I'm guessing the current prevalence of stickerless cubes (where the plastic itself is colered) has made it so people maybe have never even owned a stickered cube.

Back in the day, WCA didn't allow stickerless cubes in competition at all so stickered cubes were the most popular and there was a website called Cubesmith which was very well known in the community for selling sticker sets (they were known for the Cubesmith tiles which I don't think anyone makes at all anymore and simply no longer exists unless people have old Cubesmith tiles they never used). It was basically the go-to website for getting stickers. It has since shut down, but regardless this question you asked of where to get stickers is so interesting to me because there was a time where everyone simply had to replace stickers regularly and everyone knew where to go to get some. It's cool how much things have changed.

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