#turbulence — Public Fediverse posts

Weekly Update from the Open Journal of Astrophysics 08/08/2026

Although it’s holiday season for some, it’s time once more for another Saturday update of activity at the Open Journal of Astrophysics. Since the last update we have published a further four papers, bringing the number in Volume 9 (2026) to 167 and the total so far published by OJAp up to 615.

I continue to include the posts made on our Mastodon account (on Fediscience); these announcements also show the DOI for each paper.

The first paper to report this week was published on Tuesday 4th August in the folder Astrophysics of Galaxies with the title “Small-scale turbulence alongside large-scale turbulence in a z=1.87 star-forming galaxy with an outflowing wind, revealed by multi-point structure functions” by Itzhak Goldman (Afeka College, Israel). A previous study by the author found evidence of large and small scale turbulence in the star-forming galaxy CSWA13, suggesting that star clusters and large clumps within the galaxy could be driving this turbulence.

The overlay for this paper is here

You can find the officially accepted version on arXiv here and the announcement on Fediverse here:

https://fediscience.org/@OJ_Astro/117036181269903989

The second paper for this week, published on Thursday 6th August in the folder Astrophysics of Galaxies, is “From Clumps to Sheets: Geometry Controls the Temperature PDF of Multi-Phase Gas” by Zirui Chen and S. Peng Oh (UC Santa Barbara, USA). This study uses 3D hydrodynamic simulations to show that the temperature probability distribution functions (PDFs) of multi-phase turbulent gas differ significantly under interstellar medium (ISM) and circumgalactic medium (CGM) conditions.

The overlay looks like this:

The official version of the paper can be found on arXiv here and the Fediverse announcement here:

https://fediscience.org/@OJ_Astro/117047322340826393

The third paper of the week, published on Thursday 6th August in folder Instrumentation and Methods for Astrophysics is “First Detection of Extensive Air Showers Using a Small-Aperture Fluorescence Telescope” by M. Zotov (M.V. Lomonosov Moscow State University, Russia) and 7 others based in Russia and Armenia. The study reports the first-ever detection of extensive air showers from ultra-high-energy cosmic rays using a compact fluorescence telescope, employing both conventional and deep learning analysis methods.

The overlay is here:

The official version of the paper can be found on arXiv here and the Fediverse announcement here:

https://fediscience.org/@OJ_Astro/117047408583672745

The fourth and final paper of the week was published on Friday 7th August in the folder Cosmology and Nongalactic Astrophysics: “TDCOSMO XXVI: Uniform Lens Modeling of Eight Doubly Imaged Quasars“, by Ryan Brady (Stony Brook University, USA) and 9 others based all around the world, presents a new method for analyzing doubly imaged quasars using the Hubble Space Telescope, revealing that arc surface brightness is key to precision in mass model measurements.

The overlay is here:

The officially-accepted version of the paper can be found on arXiv here and the Fediverse announcement here:

https://fediscience.org/@OJ_Astro/117053056092162466

That’s all for this week. We have about a dozen more papers accepted and waiting for the authors to put the final version on arXiv, which they will presumably do when they’re back from holiday. I’ll do an update next weekend and we’ll see!

Weekly Update from the Open Journal of Astrophysics – 07/02/2026

It’s Saturday once more so time for another update of activity at the Open Journal of Astrophysics. Since the last update we have published a further six papers, bringing the number in Volume 9 (2026) to 24 and the total so far published by OJAp up to 472.

I will continue to include the posts made on our Mastodon account (on Fediscience) to encourage you to visit it. Mastodon is a really excellent service, and a more than adequate replacement for X/Twitter which nobody should be using; these announcement also show the DOI for each paper.

The first paper to report this week is “The Impact of Star Formation and Feedback Recipes on the Stellar Mass and Interstellar Medium of High-Redshift Galaxies” by Harley Katz (U. Chicago, USA), Martin P. Rey (U. Oxford, UK), Corentin Cadiou (Lund U., Sweden) Taysun Kimm (Yonsei U., Korea) and Oscar Agertz (Lund). This paper was published on Monday 2nd February 2026 in the folder Astrophysics of Galaxies. It introduces MEGATRON, a new model for galaxy formation simulations, highlighting that feedback energy controls star formation at high redshift and highlighting the importance of the interstellar medium.

The overlay is here:

You can find the officially accepted version on arXiv here and the announcement on Fediverse here:

https://fediscience.org/@OJ_Astro/116000695648050758

The second paper is “Photometric Redshifts in JWST Deep Fields: A Pixel-Based Alternative with DeepDISC” by Grant Merz (U. Illinois at Urbana-Champaign) and 6 others, all based in the USA. This paper was published on Monday February 2nd 2026 in the folder Instrumentation and Methods for Astrophysics. This paper explores the effectiveness of the DeepDISC machine learning algorithm in estimating photometric redshifts from near-infrared data, demonstrating its potential for larger image volumes and spectroscopic samples

The overlay for this one is here:

The official version of the paper can be found on arXiv here and the Fediverse announcement here:

https://fediscience.org/@OJ_Astro/116000777572439111

Next, published on Wednesday 4th February in the folder Astrophysics of Galaxies, is “Inferring Interstellar Medium Density, Temperature, and Metallicity from Turbulent H II Regions” by Larrance Xing (U. Chicago, USA), Nicholas Choustikov (U. Oxford, UK), Harley Katz (U. Chicago) and Alex J. Cameron (DAWN, Denmark). This paper argues that supersonic turbulenc affects the interpretation of H II region properties, potentially impacting inferred metallicity, ionization, and excitation from in nebular emission lines, motivating more extensive modelling.

The overlay is here:

The official version can be found on arXiv here and the Fediverse announcement is here:

https://fediscience.org/@OJ_Astro/116011384659092223

The fourth paper this week, also published on Wednesday 4th February, but in the folder Solar and Stellar Astrophysics, is “A Systematic Search for Big Dippers in ASAS-SN” by B. JoHantgen, D. M. Rowan, R. Forés-Toribio, C. S. Kochanek, & K. Z. Stanek (Ohio State University, USA), B. J. Shappee (U. Hawaii, USA), Subo Dong (Peking University), J. L. Prieto Universidad Diego Portales, Chile) and Todd A. Thompson (Ohio State). This study identifies 4 new dipper stars and 15 long-period eclipsing binary candidates using ASAS-SN light curves and multi-wavelength data, categorizing them based on their characteristics.

Here is the overlay:

The official version can be found on arXiv here and the Fediverse announcement is here:

https://fediscience.org/@OJ_Astro/116011460612040834

Fifth, and next to last this week we have “Unveiling the drivers of the Baryon Cycles with Interpretable Multi-step Machine Learning and Simulations” by Mst Shamima Khanom, Benjamin W. Keller and Javier Ignacio Saavedra Moreno (U. Memphis, USA). This paper was published on Thursday 5th February 2026 in the folder Astrophysics of Galaxies. This study uses machine learning methods to understand how galaxies lose or retain baryons, highlighting the relationship between baryon fraction and various galactic measurements.

The overlay is here:

The accepted version can be found on arXiv here, and the fediverse announcement is here:

https://fediscience.org/@OJ_Astro/116016883984380622

Finally for this week we have “The Bispectrum of Intrinsic Alignments: II. Precision Comparison Against Dark Matter Simulations” by Thomas Bakx (Utrecht U., Netherlands), Toshiki Kurita (MPA Garching, Germany), Alexander Eggemeier (U. Bonn, Germany), Nora Elisa Chisari (Utrecht) and Zvonimir Vlah (Ruđer Bošković Institute, Croatia). This paper was accepted in December, but publication got delayed by the Christmas effect so was published on February 6th 2026, in the folder Cosmology and Nongalactic Astrophysics. This study uses N-body simulations to accurately measure three-dimensional bispectra of halo intrinsic alignments and dark matter overdensities, providing a method to determine higher order shape bias parameters.

The overlay is here:

You can find the published version of the article here, and the Mastodon announcement is here:

https://fediscience.org/@OJ_Astro/116022562915557971

And that concludes this week’s update. I will do another next Saturday.

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

Simulating a Sneeze

Sneezing and coughing can spread pathogens both through large droplets and through tiny, airborne aerosols. Understanding how the nasal cavity shapes the aerosol cloud a sneeze produces is critical to understanding and predicting how viruses could spread. Toward that end, researchers built a “sneeze simulator” based on the upper respiratory system’s geometry. With their simulator, the team mimicked violent exhalations both with the nostrils open and closed — to see how that changed the shape of the aerosol cloud produced.

The researchers found that closed nostrils produced a cloud that moved away along a 18 degree downward tilt, whereas an open-nostril cloud followed a 30-degree downward slope. That means having the nostrils open reduces the horizontal spread of a cloud while increasing its vertical spread. Depending on the background flow that will affect which parts of a cloud get spread to people nearby. (Image and research credit: N. Catalán et al.; via Physics World)

#aerosols #biology #coughing #COVID19 #diseaseTransmission #droplets #flowVisualization #fluidDynamics #physics #science #sneezing #turbulence

Salt Affects Particle Spreading

Microplastics are proliferating in our oceans (and everywhere else). This video takes a look at how salt and salinity gradients could affect the way plastics move. The researchers begin with a liquid bath sandwiched between a bed of magnets and electrodes. Using Lorentz forcing, they create an essentially 2D flow field that is ordered or chaotic, depending on the magnets’ configuration. Although it’s driven very differently, the flow field resembles the way the upper layer of the ocean moves and mixes.

The researchers then introduce colloids (particles that act as an analog for microplastics) and a bit of salt. Depending on the salinity gradient in the bath, the colloids can be attracted to one another or repelled. As the team shows, the resulting spread of colloids depends strongly on these salinity conditions, suggesting that microplastics, too, could see stronger dispersion or trapping depending on salinity changes. (Video and image credit: M. Alipour et al.)

#2024gofm #electrohydrodynamics #flowVisualization #fluidDynamics #geophysics #magneticField #physics #plasticPollution #science #turbulence

Kolmogorov Turbulence

Turbulent flows are ubiquitous, but they’re also mindbogglingly complex: ever-changing in both time and space across length scales both large and small. To try to unravel this complexity, scientists use simplified model problems. One such simplification is Kolmogorov flow: an imaginary flow where the fluid is forced back and forth sinusoidally. This large-scale forcing puts energy into the flow that cascades down to smaller length scales through the turbulent energy cascade. Here, researchers depict a numerical simulation of a turbulent Kolmogorov flow. The colors represent the flow’s vorticity field. Notice how your eye can pick out both tiny eddies and larger clusters in the flow; those patterns reflect the multi-scale nature of turbulence. (Image credit: C. Amores and M. Graham)

#2024gofm #flowVisualization #fluidDynamics #Kolmogorov #numericalSimulation #physics #science #turbulence #turbulentEnergyCascade

Visualizing Unstable Flames

Inside a combustion chamber, temperature fluctuations can cause sound waves that also disrupt the flow, in turn. This is called a thermoacoustic instability. In this video, researchers explore this process by watching how flames move down a tube. The flame fronts begin in an even curve that flattens out and then develops waves like those on a vibrating pool. Those waves grow bigger and bigger until the flame goes completely turbulent. Visually, it’s mesmerizing. Mathematically, it’s a lovely example of parametric resonance, where the flame’s instability is fed by system’s natural harmonics. (Video and image credit: J. Delfin et al.; research credit: J. Delfin et al. 1, 2)

#2024gofm #combustion #combustionInstability #flame #flowVisualization #fluidDynamics #instability #parametricResonance #physics #resonance #science #thermoacousticInstability #turbulence