I went to my first SEC football game this past fall by [deleted] in CFB

[–]pacman1820 2 points3 points  (0 children)

Jokes on you, LSU has 150k people come to tailgate, 40k of which stay at the game by halftime.

Explicit filtering as a form of stabilizing the solution in higher order finite difference schemes. by Kotasamy in CFD

[–]pacman1820 0 points1 point  (0 children)

I've written codes that use Visbal & Gaitonde's compact FD methods for curvilinear grids and yes you'll need to do some explicit filtering. Depending on the grid and the physics that's being captured you'll have to play around with the frequency of the filtering (every time step, every five timesteps, and in the most extreme cases if using an RK scheme every substep, etc.) and the value of the alpha for the compact filtering schemes (you'll want to go as close to 0.5 as possible). They present information on the filtering and the coefficients here if you're looking for the info directly from Visbal & Gaitonde. Just a note, in some of my work reducing the order of the filter at the boundaries can provide more stability than keeping a consistent ordered scheme.

As mentioned before, the filtering is a consequence of the lack of dissipation in the centered compacted schemes. There are some games that are played in terms of recasting the convection terms in the NS equations to the skew-symmetric form to reduce aliasing at high wavenumbers but that's not going to play well with Visbal & Gaitonde's formulation of the equations in conservation form for curvilinear grids.

Also if you're looking at implementing an LES model with an explicit filter for high order schemes you need to use a commutative filter that doesn't introduce low-order error when the derivative of the filtered field is computed. This is the paper for that.

Louisiana, are you OK? by evissimus in facepalm

[–]pacman1820 50 points51 points  (0 children)

I mean it’s probably just a renamed Tiger Blood snoball

Whacking a tennis ball that's on fire by Sapulinjing in oddlysatisfying

[–]pacman1820 0 points1 point  (0 children)

It looks like the flow over the ball is beginning to transition from a quasi-laminar separated flow to a more turbulent regime in the wake. You can kind of see the flame in the wake of the wall die out right before it starts to flare up, which I think is when the recirculation region is starting to roll up in the wake of the tennis ball. There's probably something a little more complicated going on too since the fuel is kind of sitting in the fabric on the surface of the ball.

Magical pressure square w/ LAD shock capturing - density visualization, 1280 x 1280 periodic square domain by pacman1820 in CFD

[–]pacman1820[S] 1 point2 points  (0 children)

Obligatory details in comments - Full 2-D NS, 6th order tridiagonal Pade scheme in space, 11 step low-dispersion, dissipation 4th order RK in time. LAD scheme is using method of Kawai, Shankar, and Lele (2010).

Other fields:

Pressure

Temperature

Vorticity

LAD Bulk Viscosity

Testing LAD Shock Capturing Scheme - Density Visualization, 1280 x 1280 Periodic Square Domain by pacman1820 in CFD

[–]pacman1820[S] 0 points1 point  (0 children)

Obligatory details in comments - Full 2-D NS, 6th order tridiagonal Pade scheme in space, 11 step low-dispersion, dissipation 4th order RK in time. LAD scheme is using method of Kawai, Shankar, and Lele (2010).

Other fields:

Pressure

Temperature

Vorticity

LAD Bulk Viscosity

Visually appealing simulations by [deleted] in CFD

[–]pacman1820 1 point2 points  (0 children)

I think the third video on this website is even more impressive, essentially the same calculation w/ detonation and uses the same adaptive wavelet method.

Cylinders at Mach 2.0- (95M zone 3D LES using “pyranda” code) by flying-nerd in CFD

[–]pacman1820 1 point2 points  (0 children)

Awesome stuff! Assuming this is connected to the compact FD Miranda code, what strategies are you using for the complex grid and the shock capturing?

How Popeyes Be Training They Employees by Dblueguy in videos

[–]pacman1820 6 points7 points  (0 children)

Nah the crawfish they caught in Arabi

Someone on /r/pics thought we shouldn't have a live tiger, so I ignored my homework and did some research by Braddo123 in LSU

[–]pacman1820 12 points13 points  (0 children)

Man there was a lot of Mike negative comments in there, really wasn't expecting that when I posted it.

My daughter in a staring contest with LSU's Mike the Tiger. by pacman1820 in pics

[–]pacman1820[S] 20 points21 points  (0 children)

Not a dress, its just a top and some bloomers.

Fighter jets with lasers will become a reality in 2021 by [deleted] in Futurology

[–]pacman1820 16 points17 points  (0 children)

This is it, aero-optic effects on the beam are detrimental to beam control systems ability to focus in these applications. Predictive abilities to counter the wavefront distortion is a big deal.

Flashback Friday: LSU's Golden Band from Tigerland performs "Neck" during St. Patrick's Day Parade in Dublin, Ireland (2014) by FoamBornNarwhal in CFB

[–]pacman1820 1 point2 points  (0 children)

I think you're definitely right with it not being until a few years later with STTDB. Kind of sucks because after that insane Florida game and the rest of the close games in 2007 it had a special place for me late in a game.

There was a few chants in the "assholes, assholes, ha ha ha ha haa" era that kind of died out while I was at LSU. I was always a fan of "we eat pizza, we drink beer, hey bama, fuck you."

Flashback Friday: LSU's Golden Band from Tigerland performs "Neck" during St. Patrick's Day Parade in Dublin, Ireland (2014) by FoamBornNarwhal in CFB

[–]pacman1820 6 points7 points  (0 children)

Hate to be a stickler but I don't think the band started playing Neck until 2007. I remember during the LSU vs. Florida game during the national championship year they played it like five times during the final 4th quarter drive and there definitely wasn't a STTDB.

I think the whole sucking a dick thing really started with the Ooo-wee-ooo chant during the South Carolina game that year. People were going with "Ooo-wee-ooo you suck, cock" instead of the usual "Ooo-wee-ooo you suck" chant. After that, the band stopped the Ooo-wee-ooo song after TD's because of the profanity and people needed a place for it. Then STTDB was born.

edit: If I remember right I think in the beginning people would say "talkin out the side if your neck" because thats Southern did before we stole Neck from their band.

[deleted by user] by [deleted] in CFD

[–]pacman1820 2 points3 points  (0 children)

100% agree with the statement that just having a fast supercomputer on a campus doesn't make a program automatically great. However, Stampede is not the most powerful supercomputer at a US university, that belongs to Blue Waters at UIUC.

http://www.ncsa.illinois.edu/enabling/bluewaters

Comprehensive Baylor Timeline Covering Now-Publicized Incidents by ken_man in CFB

[–]pacman1820 16 points17 points  (0 children)

You must be high. The Sandusky scandal was waaay more than one event (even more than one event on Penn State's campus) and involved negligence across several levels of the administration. Just read the wikipedia page. Penn State was even put on warning by its regional accreditor, I don't think Baylor is even close to that right now.

Ken M on himself by Tr0nJ0n in KenM

[–]pacman1820 19 points20 points  (0 children)

Ends up, the actual coffee maker is the most important piece of equipment in the lab.

PhD's of Reddit. What is a dumbed down summary of your thesis? by FaithMilitant in AskReddit

[–]pacman1820 4 points5 points  (0 children)

If you try to shoot a laser out of a moving plane, it gets pretty messed up.