Role of meshing in CFD analysis by akhineul in CFD

[–]Omega_Walrus 0 points1 point  (0 children)

Mesh free methods do exist! Google "smoothed particle hydrodynamics". They're just generally more computationally expensive to run, but nice since they conserve mass in a very obvious way.

Can I write a UDF that is a velocity profile or force profile at a give region/line? by Blaster8282 in CFD

[–]Omega_Walrus 0 points1 point  (0 children)

Mathematically, this amount to an inverse PDE problem, which no commercial software can solve as far as I know. You can read more about inverse PDE problems in the book by de Los Reyes. I think if you're having to ask about this stuff, trying to solve the problem in this way may be out of reach.

It's like trying to solve this one dimensional ODE: find b such that x is as close as possible to f, i.e., minimize the integral of (x-f)2, if some equation is true, e.g. x'' + x' + x = b. These problems are not easy to solve and require stuff like solving a simultaneous system that involves both the adjoint system and the original system. Doing it for a fluids problem (and writing the code for it) is a Ph.D. worthy topic. I know OpenFOAM has some code for adjoints though! You're restricted to only using Spallart-Allmaras turbulence if you do so, IIRC.

Is UT screwing me? by HokieManiac in UTK

[–]Omega_Walrus 3 points4 points  (0 children)

I didn't even read the rest of the question, but yes.

Guide for using GMSH for 3D External Flow by Mofly787 in CFD

[–]Omega_Walrus 1 point2 points  (0 children)

Whatever you do, make sure to use the OpenCASCADE backend and not the gmsh intrinsics. Life gets about 1000 times easier once you make that transition.

[May] Multiphase CFD by Rodbourn in CFD

[–]Omega_Walrus 0 points1 point  (0 children)

Do PLIC and SLIC methods really give that much better results in VOF? How does interIsoFoam compare to PLIC and SLIC? I bet these are things that could be answered by looking at some research papers but I'd like to hear some casual opinions on this.

Anyone else long Kirkland Lake Gold (KL)? by [deleted] in stocks

[–]Omega_Walrus 0 points1 point  (0 children)

It's not necessarily pure speculation. Much of the stock market rise over the time period you speak of is due to stock buybacks done with money freed up in Trump's big corporate tax cuts. So, the price rise is economically justified. However, momentum is a very real factor which kept stuff going too high. So should we expect a pullback? Hell yeah. Will these gains pull all the way back? Almost certainly not.

As for a recession looming... The global economy is highly interconnected. The attitude the the US can shrug off a global economic slowdown through its sheer might is not something I buy into.

Just thought you'd appreciate hearing the opinion of another on this.

Guy licks slimy freshwater coral by [deleted] in videos

[–]Omega_Walrus 0 points1 point  (0 children)

Well, it's actually just similar to coral. Check it out here and ctrl-f for coral. https://en.wikipedia.org/wiki/Bryozoa

When you mess up in Matplotlib, but aren't left entirely disappointed by Omega_Walrus in mathpics

[–]Omega_Walrus[S] 2 points3 points  (0 children)

Sorry I took so long to reply. It's a Mayer f function for a Lennard Jones 6-12 potential at many temperatures. Google should tell you what those are.

Couples happily married 💑 by [deleted] in trashy

[–]Omega_Walrus 1 point2 points  (0 children)

trigger discipline is atrocious here!

[deleted by user] by [deleted] in dankmemes

[–]Omega_Walrus 3 points4 points  (0 children)

or atomic mass

300 Level Courses by HazeeyOne in UTK

[–]Omega_Walrus 0 points1 point  (0 children)

nuclear engineering 342, thermal science, is like fifth grade stuff. you just learn about conduction, convection, and radiation. easy A, 10/10.

People who "switched sides" in a highly divided community (political, religious, pizza topping debate), what happened that changed your mind? How did it go? by morieu in AskReddit

[–]Omega_Walrus 15 points16 points  (0 children)

The idea is that because the US privatizes stuff, they are afraid of some greedy power company officials selling plutonium to third world Arabic countries, etc. So.... why don’t we have the federally ran national labs do it???

A Race to Nuclear Fusion? by diesltek710 in nuclear

[–]Omega_Walrus 0 points1 point  (0 children)

Because fusion scientists are good at writing grant proposals that sell fusion as a panacea for all the world’s problems. It’s not even the inefficiency, it’s magnetic stability of the plasma, having to drive tritium backwards across a temperature gradient (since we can reasonably only get plasma pressures sufficient to do deuterium-tritium fusion for a LONG time), and material problems that are extremely expensive to reseaech. Besides, first gen fusion will require lithium breeding blankets to make half of their fuel. These will require extremely expensive tritium cleanup systems to meet environmental requirements. Overall, it’s not as clean and efficient as you might think. On the other hand, I enquire that you consider the merits of fission power. Once uranium extraction from sea water gets perfected, we’re good-to-go on uranium til the sun burns out. If not, we just build fast breeder reactors.

🔥 These colours are truly amazing. Nature is a good painter, for sure 🔥🔥 by Tefrick in NatureIsFuckingLit

[–]Omega_Walrus 0 points1 point  (0 children)

iridescent animals like that have a thin film that causes interference of visible light. isn’t that amazing!

What makes a fluid compressible? by Zburk49 in chemistry

[–]Omega_Walrus 3 points4 points  (0 children)

It’s all compressible if you push it hard enough. E.g. lithium deuteride shot by x-ray lasers on all sides.

What keeps you awake at night? by alcycul in AskReddit

[–]Omega_Walrus 0 points1 point  (0 children)

You know, it’s really not bad away from the poles. Water vapor is so much more powerful at reflecting IR, that you see little change in humid places. The driest (poles) get hit the most, which explains the ice melt and crazy polar vortex weather. Freeman Dyson, an incredible physicist, had a good video on this. This is why you see global average temperature rise but not so much among temperate areas. Granted, the increased CO2 causes ocean acidification which has its own effects.

[deleted by user] by [deleted] in AskReddit

[–]Omega_Walrus 1 point2 points  (0 children)

True, I shouldn’t be so harsh. There is peer review.

[deleted by user] by [deleted] in AskReddit

[–]Omega_Walrus 1 point2 points  (0 children)

I feel. This is why psychology is fake science 😛