ExaWind Simulation

Large-scale computational fluid dynamics simulations face many challenges. Among them is the need to capture both large physical scales–like those of Earth’s atmospheric boundary layer–and small scales–like those of tiny eddies moving around a wind-turbine blade. Capturing all of these scales for a problem like four wind turbines in a wind farm requires using the full computing power of every processor in a large supercomputer. That’s the level of power behind the simulation visualized in this video. The results, however, are stunning. (Video and image credit: M. da Frahan et al.)

Having Just Realized™ that I can use Sphere Glyphs to render my particles in #ParaView, I am now Very Happy™ because my low-resolution #SPH simulations can be made to appear so much nicer.

#SmoothedParticleHydrodynamics #CFD #ComputationalFluidDynamics #rendering #visualization

Now that I have a reasonably fast CPU again I descended into the #CFD rabbit hole again. #OpenFOAM has a really steep learning curve (it is the opposite of plug-and-play). I last touched it in 2016. So far I have mostly modified some tutorial projects, but it is fascinating. The image shows the pressure distribution (red: higher, blue: lower) on a crude P.180 model created in #OpenVSP.

#computationalfluiddynamics

Oceans Could “Burp” Out Absorbed Heat

Earth’s atmosphere and oceans form a complicated and interconnected system. Water, carbon, nutrients, and heat move back and forth between them. As humanity pumps more carbon and heat into the atmosphere, the oceans–and particularly the Southern Ocean–have been absorbing both. A new study looks ahead at what the long-term consequences of that could be.

The team modeled a scenario where, after decades of carbon emissions, the world instead sees a net decrease in carbon–which could be achieved by combining green energy production with carbon uptake technologies. They found that, after centuries of carbon reduction and gradual cooling, the Southern Ocean could release some of its pent-up heat in a “burp” that would raise global temperatures by tenths of a degree for decades to a century. The burp would not raise carbon levels, though.

The research suggests that we should continue working to understand the complex balance between the atmosphere and oceans–and how our changes will affect that balance not only now but in the future. (Image credit: J. Owens; research credit: I. Frenger et al.; via Eos)

#CFD #climateChange #computationalFluidDynamics #fluidDynamics #geophysics #heatTransfer #numericalSimulation #ocean #physics #science

Waves Over Sand Ripples

Look beneath the waves on a beach or in a bay, and you’ll find ripples in the sand. Passing waves shape these sandforms and can even build them to heights that require dredging to keep waterways passable to large ships. To better understand how the sand interacts with the flow, researchers build computer models that couple the flow of the water with the behavior of individual sand grains. One recent study found that sand grains experienced the most shear stress as the flow first accelerates and then again when a vortex forms near the crest of the ripple. (Image credit: D. Hall; research credit: S. DeVoe et al.; via Eos)

#CFD #computationalFluidDynamics #fluidDynamics #geophysics #granularMaterial #oceanWaves #physics #sandRipples #science #sedimentTransport #sedimentation

The next issue of the #SPHERIC #newsletter is fresh out, go download it from https://www.spheric-sph.org/newsletters

#SPH #CFD #ComputationalFluidDynamics

Physics of badminton’s new killer spin serve https://arstechni.ca/3NeW #computationalfluiddynamics #physicsofsports #fluiddynamics #sportsscience #badminton #Science #Physics

Bow Shock Instability

There are few flows more violent than planetary re-entry. Crossing a shock wave is always violent; it forces a sudden jump in density, temperature, and pressure. But at re-entry speeds this shock wave is so strong the density can jump by a factor of 13 or more, and the temperature increase is high enough that it literally rips air molecules apart into plasma.

Here, researchers show a numerical simulation of flow around a space capsule moving at Mach 28. The transition through the capsule’s bow shock is so violent that within a few milliseconds, all of the flow behind the shock wave is turbulent. Because turbulence is so good at mixing, this carries hot plasma closer to the capsule’s surface, causing the high temperatures visible in reds and yellows in the image. Also shown — in shades of gray — is the vorticity magnitude of flow around the capsule. (Image credit: A. Álvarez and A. Lozano-Duran)

#2024gofm #CFD #computationalFluidDynamics #flowVisualization #fluidDynamics #hypersonic #instability #numericalSimulation #physics #science #shockWave #turbulence

Talking about dependencies: one thing we did *not* reimplement in #GPUSPH is rigid body motion. GPUSPH is intended to be code for #CFD, and while I do dream about making it a general-purpose code for #ContinuumMechanics, at the moment anything pertaining solids is “delegated”.

When a (solid) object is added to a test case in GPUSPH, it can be classified as either a “moving” or a “floating” object. The main difference is that a “moving” object is assumed to have a prescribed motion, which effectively means the user has to also define how the object moves, while a “floating” object is assumed to move according to the standard equations of motion, with the forces and torques exerted on the body by the fluid provided by GPUSPH.

For floating objects, we delegate the rigid body motion computation to the well-established simulation engine #ProjectChrono
https://projectchrono.org/

Chrono is a “soft dependency” of GPUSPH: you do not need it to build a generic test case, but you do need it if you want floating objects without having to write the entire rigid body solver yourself.

1/n

#SmoothedParticleHydrodynamics #SPH #ComputationalFluidDynamics

This thread about writing games vs writing game engines <https://peoplemaking.games/@eniko/114137694102639793> by @eniko, and the comments within by many other people, is a fascinating read for me, particularly in relation to the similarities and the differences with our experience in the development of what is, for all intents and purposes, a #CFD engine, but also many of the test cases it has been used for.

For many #ComputationalFluidDynamics methods, it's actually pretty simple to write an implementation for a “trivial” test case (straight walls, right angles if any at all, periodic boundary conditions, etc). We did that for example in a couple of hours during the MODCLIM 2016 training school https://modclim.ulpgc.es/index.php/events/8-modclim-events

Things become quickly non-trivial as soon as you start needing

1. non-trivial geometries

and

2. more complex physics and/or more sophisticated methods.

1/

How CO2 Gets Into the Ocean

Our oceans absorb large amounts of atmospheric carbon dioxide. Liquid water is quite good at dissolving carbon dioxide gas, which is why we have seltzer, beer, sodas, and other carbonated drinks. The larger the surface area between the atmosphere and the ocean, the more quickly carbon dioxide gets dissolved. So breaking waves — which trap lots of bubbles — are a major factor in this carbon exchange.

This video shows off numerical simulations exploring how breaking waves and bubbly turbulence affect carbon getting into the ocean. The visualizations are gorgeous, and you can follow the problem from the large-scale (breaking waves) all the way down to the smallest scales (bubbles coalescing). (Video and image credit: S. Pirozzoli et al.)

#2024gfm #breakingWave #bubbles #carbonCycle #carbonDioxide #CFD #climateChange #computationalFluidDynamics #dissolution #flowVisualization #fluidDynamics #numericalSimulation #physics #science #turbulence

Hello all! This will be the official #GPUSPH account on the Fediverse going forward. What is GPUSPH, you ask? It's a software for #ComputationalFluidDynamics using the #SmoothedParticleHydrodynamics method, accelerated by running entirely* on GPU. In fact, it was the first to do so, leveraging the new GPGPU capabilities offered by NVIDIA CUDA.

(These days we have wider hardware support, but for a long time CUDA was all we supported.)

#introduction #newHere #CFD #HPC

*conditions apply

In recent years, Arctic permafrost has thawed at a surprisingly fast pace. Much of that is, of course, due to the rapid warming caused by climate change. But some of that phenomenon lives underground, where water’s unusual properties cause convection in gaps between rocks, sediment, and soil.

Water is densest not as ice but as water. This is why ice cubes float in your glass. Water’s densest form is actually a liquid at 4 degrees Celsius. For water-logged Arctic soils, this means that the densest layer is not at the frozen depth but at a higher, shallower depth. This places a dense liquid-infused layer over a lighter one, a recipe for unstable convection.

In a recent numerical simulation, researchers found that this underground convection caused permafrost to thaw much more quickly than it would due to heat conduction alone. In fact, the effects appeared in as little as one month, so in a single summer, this convection could have a big effect on the thaw depth. (Image credit: top – Florence D., figure – M. Magnani et al.; research credit: M. Magnani et al.)

https://fyfluiddynamics.com/2024/10/underground-convection-thaws-permafrost-faster/

#CFD #computationalFluidDynamics #convection #fluidDynamics #geophysics #instability #numericalSimulation #permafrost #physics #planetaryScience #science

The Gulf Stream current carries warm, salty water from the Gulf of Mexico northeastward. In the North Atlantic, this water cools and sinks and drifts southwestward, emerging centuries later in the Southern Ocean. Known as the Atlantic Meridional Overturning Circulation (AMOC), this circulation is critical, among other things, to Europe’s temperate climate. Since 1995, scientists have been warning that human-driven climate change is weakening the AMOC and may cause it to shut down entirely — which would have catastrophic consequences for our society.

A recent study re-examined the AMOC using both low- and high-resolution numerical simulations, combined with direct observations. Both simulations covered 1950 – 2100 and found the AMOC’s strength has declined since 1950. But the high-resolution simulation found significant regional variations in the AMOC’s behavior. Some regions saw localized strengthening, while other areas showed abrupt collapse. These sensitive shifts underscore the importance of driving toward higher resolutions in our next-generation climate models, if we want to better understand — and perhaps predict — what lies ahead as our climate changes. (Image credit: illustration – Atlantic Oceanographic and Meteorological Laboratory, simulations – R. Gou et al.; research credit: R. Gou et al.; via APS Physics)

https://fyfluiddynamics.com/2024/08/resolution-effects-on-ocean-circulation/

#CFD #circulation #climateChange #computationalFluidDynamics #flowVisualization #fluidDynamics #numericalSimulation #oceanCurrents #oceanography #physics #science

Growing up in northwest Arkansas, I spent my share of summer nights sheltering from tornadoes. Central North America — colloquially known as Tornado Alley — is especially prone to violent thunderstorms and accompanying tornadoes. That’s due, in part, to two geographical features: the Rocky Mountains and the Gulf of Mexico. Trade winds hitting the eastern slope of the Rockies get turned northward, imparting a counterclockwise vorticity. At the same time, warm moist air carried from the Gulf feeds into the atmosphere, creating perfect conditions for powerful thunderstorms. By this logic, though, South America should see lots of tornadoes, too, courtesy of the Andes Mountains and the moist environs of the Amazon Basin. To understand why South America doesn’t have a Tornado Alley, researchers used global weather models to investigate alternate North and South Americas.

They found that smoothness is a key ingredient for the upstream, moisture-generating region. Compared to the Amazon, the Gulf of Mexico is incredibly flat. With a flat Gulf, tornadoes abounded in North America, but their numbers dropped once that area was roughened to mimic the Amazon. The opposite held true, too: a smoothed-out Amazon Basin resulted in more simulated South American tornadoes.

For those in Tornado Alley, the results don’t offer much hope for mitigating our summer storms — we can’t exactly roughen the ocean. But the study does sound a word for warning for South America; the smoother the Amazon region becomes — due to mass deforestation — the more likely tornadoes become in parts of South America. (Image credit: G. Johnson; research credit: F. Li et al.; via Physics World)

https://fyfluiddynamics.com/2024/08/why-tornado-alley-is-north-american/

#atmosphericScience #CFD #computationalFluidDynamics #fluidDynamics #meteorology #physics #science #surfaceRoughness #thunderstorm #tornado #vorticity

Venus flower basket sponges have an elaborate, vase-like skeleton pocked with holes that allow water to pass through the organism. A recent numerical study looked at how the sponge’s shape deflects incoming (horizontal) ocean currents into a vertical flow the sponge can use to filter out food.

The sponges’ structure is porous and lined with helical structures. In their simulation, researchers reproduced a version of this structure (shown below) that used none of the real sponge’s active pumping mechanisms. The digital sponge was, instead, purely passive. Nevertheless, the simulation showed that, by their skeletal structure alone, sponges could redirect a significant fraction of incoming flow toward its filtering surfaces. Interestingly, the highest deflection fraction occurred at relatively low flow speeds, showing that the sponges are set up so that their structure is especially helpful for scavenging nutrients from nearly-still waters.

In the real world, these sponges use a combination of passive filtering and active pumping to capture their food, but this study shows that the sponge’s clever structure helps it save energy, especially in tough flow conditions. (Image credit: sponges – NOAA, simulation – G. Falcucci et al.; research credit: G. Falcucci et al.; via APS Physics)

https://fyfluiddynamics.com/2024/06/venus-flower-basket-sponges/

#biology #CFD #computationalFluidDynamics #filterFeeding #fluidDynamics #numericalSimulation #physics #porousFlow #science

I also want to explore more #GeometricAlgebra applied to #physics and #ComputationalPhysics (not necessarily for #FluidDynamics and #CFD, but that would be preferable as it's obviously our primary topic of relevance). I can't seem to find anything that combines #SPH and GA, so it might even lead to some new interesting venues to explore.

3/n

#ComputationalFluidDynamics #SmoothedParticleHydrodynamics

Does anybody know of #Lemmy communities/magazines centered around any of these topics:

#CFD aka #ComputationalFluidDynamics

#SPH aka #SmoothedParticleHydrodynamics

The closest I can find is @fluidmechanics

date: 2023-02-11 22:21:21
by: PhdScanner

✅ Passionate about #airquality and #health ?

✅ 3️⃣ year fully funded #phdposition on designing #sustainable methods for airborne particle spread @KTHuniversity

🗓️Deadline: 09 Mar '23

Details 👇

https://www.kth.se/en/om/work-at-kth/lediga-jobb/what:job/jobID:591455/type:job/where:4/apply:1

#computationalfluiddynamics #Python #matlab #cfd #sweden

🐦🔗: https://twitter.com/twitter/statuses/1624534077968637956
#PhdPosition

Using my #3Dmodeling skills from industrial design, during my undergrad, I had produced a simplified model of an interpretation of how the canal system of the marine sponge Geodia barretti was structured based on epoxy casts taken off live individuals. The plan was that this 3D model was going to be given to an MSc student in engineering who would use it to later conduct #ComputationalFluidDynamics (CFD) to model the flow of the sea water being continuously pumped by the sponge. (3/4)