#fluiddynamics

Nicole SharpChanneling EspressoCoffee-making continues to be a rich source for physics insight. The roasting and brewing processes are fertile ground for chemistry, physics, and engineering. Recently, one <a href="https://arstechnica.com/science/2025/03/the-physics-of-brewing-the-perfect-espresso/?__readwiseLocation=" rel="nofollow noopener noreferrer" target="_blank">research group has focused</a> on the phenomenon of channeling, where water follows a preferred path through the coffee grounds rather than seeping uniformly through the grounds. Channeling reduces the amount of coffee extracted in the brew, which is both wasteful and results in a less flavorful cup. By uncovering what mechanics go into channeling, the group hopes to help baristas mitigate the undesirable process, creating a repeatable, efficient, and tasty espresso every time. (Image credit: <a href="https://unsplash.com/photos/person-holding-silver-steel-cup-sBS-Ufi0f1g" rel="nofollow noopener noreferrer" target="_blank">E. Yavuz</a>; via <a href="https://arstechnica.com/science/2025/03/the-physics-of-brewing-the-perfect-espresso/?__readwiseLocation=" rel="nofollow noopener noreferrer" target="_blank">Ars Technica</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/coffee/" target="_blank">#coffee</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/cooking/" target="_blank">#cooking</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/porous-flow/" target="_blank">#porousFlow</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/porous-media/" target="_blank">#porousMedia</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a>

Steven CarneiroAdvancing mathematical physics for fluid motion: <a href="https://social.vivaldi.net/tags/fluiddynamics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#fluiddynamics</a> <a href="https://social.vivaldi.net/tags/motion" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#motion</a> <a href="https://social.vivaldi.net/tags/mathematics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#mathematics</a> <a href="https://social.vivaldi.net/tags/physics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#physics</a> <a href="https://social.vivaldi.net/tags/research" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#research</a> 🤓<a href="https://www.scientificamerican.com/article/lofty-math-problem-called-hilberts-sixth-closer-to-being-solved/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.scientificamerican.com/article/lofty-math-problem-called-hilberts-sixth-closer-to-being-solved/</a>

Jochen FrommResearchers claim to have solved Hilbert’s sixth problem by unifying three theories of <a href="https://fediscience.org/tags/FluidDynamics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#FluidDynamics</a> at different levels of granularity:+ Newton’s laws of motion at the microscopic level where fluids are composed of particles - little billiard balls bopping around and occasionally colliding+ The Boltzmann equation at the mesoscopic level where the equation considers the likely behavior of a typical particle+ Euler and <a href="https://fediscience.org/tags/NavierStokes" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#NavierStokes</a> equations at the macroscopic level where the fluids are a single continuous substance<a href="https://www.scientificamerican.com/article/lofty-math-problem-called-hilberts-sixth-closer-to-being-solved" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.scientificamerican.com/article/lofty-math-problem-called-hilberts-sixth-closer-to-being-solved</a>Preprint <a href="https://arxiv.org/abs/2503.01800" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://arxiv.org/abs/2503.01800</a>

Nicole SharpFlying Without a RudderAircraft typically use a vertical tail to keep the craft from rolling or yawing. Birds, on the other hand, maneuver their wings and tail feathers to counter unwanted motions. <a href="https://doi.org/10.1126/scirobotics.ado4535" rel="nofollow noopener noreferrer" target="_blank">Researchers found</a> that the list of necessary adjustments is quite small: just 4 for the tail and 2 for the wings. Implementing those 6 controllable degrees of freedom on their bird-inspired PigeonBot II allowed the biorobot to fly steadily, even in turbulent conditions, without a rudder. Adapting such flight control to the less flexible surfaces of a typical aircraft will take time and creativity, but the savings in mass and drag could be worth it. (Image credit: E. Chang/Lentink Lab; research credit: <a href="https://doi.org/10.1126/scirobotics.ado4535" rel="nofollow noopener noreferrer" target="_blank">E. Chang et al.</a>; via <a href="https://doi.org/10.1063/pt.usov.ggrh" rel="nofollow noopener noreferrer" target="_blank">Physics Today</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/biology/" target="_blank">#biology</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/biorobotics/" target="_blank">#biorobotics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/bird-flight/" target="_blank">#birdFlight</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/birds/" target="_blank">#birds</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/flight-control/" target="_blank">#flightControl</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/turbulence/" target="_blank">#turbulence</a>

Soh Kam Yung"In the paper, the researchers suggest they have figured out how to unify three physical theories that explain the motion of fluids. [...] This breakthrough won’t change the theories themselves, but it mathematically justifies them and strengthens our confidence that the equations work in the way we think they do."<a href="https://www.scientificamerican.com/article/lofty-math-problem-called-hilberts-sixth-closer-to-being-solved/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.scientificamerican.com/article/lofty-math-problem-called-hilberts-sixth-closer-to-being-solved/</a><a href="https://mstdn.io/tags/Physics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Physics</a> <a href="https://mstdn.io/tags/Mathematics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Mathematics</a> <a href="https://mstdn.io/tags/FluidDynamics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#FluidDynamics</a> <a href="https://mstdn.io/tags/Equations" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Equations</a>

Nicole SharpSalt Fingers <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/DDinsta1.png" rel="nofollow noopener noreferrer" target="_blank"></a> <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/DDinsta2.png" rel="nofollow noopener noreferrer" target="_blank"></a> <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/DDinsta3.png" rel="nofollow noopener noreferrer" target="_blank"></a> Any time a fluid under gravity has areas of differing density, it convects. We’re used to thinking of this in terms of temperature — “hot air rises” — but temperature isn’t the only source of convection. Differences in concentration — like salinity in water — cause convection, too. This video shows a special, more complex case: what happens when there are <a href="https://en.wikipedia.org/wiki/Double_diffusive_convection" rel="nofollow noopener noreferrer" target="_blank">two sources of density gradient</a>, each of which diffuses at a different rate.The classic example of this occurs in the ocean, where colder fresher water meets warmer, saltier water (and vice versa). Cold water tends to sink. So does saltier water. But since temperature and salinity move at different speeds, their competing convection takes on a shape that resembles dancing, finger-like plumes as seen here. (Video and image credit: <a href="https://doi.org/10.1103/APS.DFD.2024.GFM.V2677989" rel="nofollow noopener noreferrer" target="_blank">M. Mohaghar et al.</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/2024gofm/" target="_blank">#2024gofm</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/convection/" target="_blank">#convection</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/double-diffusive-convection/" target="_blank">#doubleDiffusiveConvection</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/double-diffusive-instability/" target="_blank">#doubleDiffusiveInstability</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/flow-visualization/" target="_blank">#flowVisualization</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/oceanography/" target="_blank">#oceanography</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a>

Nicole SharpArctic MeltTemperatures in the Arctic are rising faster than elsewhere, triggering more and more melting. Photographer Scott Portelli captured a melting ice shelf protruding into the ocean in this aerial image. Across the top of the frozen landscape, streams and rivers cut through the ice, leading to waterfalls that flood the nearby ocean with freshwater. This meltwater will do more than raise ocean levels; it changes temperature and salinity in these regions, disrupting the convection that keeps our planet healthy. (Image credit: <a href="https://oceanographicmagazine.com/opa-winner/ocean-conservation-impact-photographer-of-the-year-2024-scopor3/" rel="nofollow noopener noreferrer" target="_blank">S. Portelli/OPOTY</a>; via <a href="https://www.thisiscolossal.com/2024/08/ocean-photographer-of-the-year-2024/" rel="nofollow noopener noreferrer" target="_blank">Colossal</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/climate-change/" target="_blank">#climateChange</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/convection/" target="_blank">#convection</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluids-as-art/" target="_blank">#fluidsAsArt</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/geophysics/" target="_blank">#geophysics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/melting/" target="_blank">#melting</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a>

Nicole SharpAtmospheric Rivers Raise TemperaturesAtmospheric rivers are narrow streams of moisture-rich air running from tropical regions to mid- or polar latitudes. Though relatively short-lived, they are capable of carrying — and depositing — more water than the largest rivers. But <a href="https://doi.org/10.1038/s41586-024-08238-7" rel="nofollow noopener noreferrer" target="_blank">researchers have found</a> that their impact is not measured in water content alone. Instead, a survey of 43 years’ worth of data shows that atmospheric rivers also bring unusually warm temperatures. In some cases, the authors found surface temperatures near an atmospheric river climbed to as high as 15 degrees Celsius above the typical. On average, temperatures were about 5 degrees Celsius higher than expected for the region’s climate. Several factors raise those temperatures — like the heat released when rising vapor meets cooler air and condenses into liquid — but the biggest effect came from carrying warm tropical temperatures to (usually) cooler regions. (Image credit: <a href="https://earthobservatory.nasa.gov/images/150804/atmospheric-river-lashes-california" rel="nofollow noopener noreferrer" target="_blank">L. Dauphin/NASA</a>; research credit: <a href="https://doi.org/10.1038/s41586-024-08238-7" rel="nofollow noopener noreferrer" target="_blank">S. Scholz and J. Lora</a>; via <a href="https://doi.org/10.1063/pt.ubik.ryhw" rel="nofollow noopener noreferrer" target="_blank">Physics Today</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/atmospheric-river/" target="_blank">#atmosphericRiver</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/atmospheric-science/" target="_blank">#atmosphericScience</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/meteorology/" target="_blank">#meteorology</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/weather/" target="_blank">#weather</a>

Nicole SharpWinter in ChicagoFresh winter snow blankets Chicago in this satellite image. Over on Lake Michigan, ice dots the coastline out to about 20 kilometers from shore. Darker regions near land mark thinner ice being pushed outward by the wind. Further out, the ice appears white and may be thicker thanks to wind-driven ice piling up. (Image credit: M. Garrison; via <a href="https://earthobservatory.nasa.gov/images/153885/a-chill-over-chicagoland" rel="nofollow noopener noreferrer" target="_blank">NASA Earth Observatory</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/ice-formation/" target="_blank">#iceFormation</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/satellite-image/" target="_blank">#satelliteImage</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/wind/" target="_blank">#wind</a>

Nicole SharpMeasuring Mucus by Dragging Dead FishA fish‘s mucus layer is critical; it protects from pathogens, reduces drag in the water, and, in some cases, protects against predators. But little is known about how mucus could affect terrestrial locomotion in species like the northern snakehead, which can breathe out of the water and move across land. So researchers explored the snakehead’s mucus layer by measuring the force required to drag them (and two other non-terrestrial species) across different surfaces.The team tested the same, freshly euthanized fish twice: once with its mucus layer intact and again once the mucus was washed off. Unsurprisingly, the fish’s friction was much lower with its mucus. But they also found that the snakehead was slipperier than either the scaled carp or the scale-free catfish. The biologists suggest that the snakehead could have evolved a slipperier mucus to help it move more easily on land, thereby extending the distance it can cover.As a fluid dynamicist, I think fish mucus sounds like a great new playground for the rheologists among us. (Image and research credit: <a href="https://doi.org/10.1093/icb/icaf002" rel="nofollow noopener noreferrer" target="_blank">F. Lopez-Chilel and N. Bressman</a>; via <a href="https://www.popsci.com/environment/fish-mucus-study/?__readwiseLocation=" rel="nofollow noopener noreferrer" target="_blank">PopSci</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/biology/" target="_blank">#biology</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fish/" target="_blank">#fish</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/rheology/" target="_blank">#rheology</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a>

Nicole SharpChaotic Hose Instability <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/chaos_hose1.png" rel="nofollow noopener noreferrer" target="_blank"></a> <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/chaos_hose2.png" rel="nofollow noopener noreferrer" target="_blank"></a> <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/chaos_hose3.png" rel="nofollow noopener noreferrer" target="_blank"></a> Steve Mould is back with another video looking at wild fluid behaviors. This time he’s considering hose instabilities like the one that makes a water-carrying hose beyond a certain length to whip wildly back and forth. He tries to track down the reasoning for these flexible hoses snapping and whipping. In truth, both the hoses and the wind dancers do their thing due to interactions between the elasticity of the hose and the fluid dynamics of the flows within. These applications are ripe for a few control volume thought experiments. (Video and image credit: S. Mould)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/chaos/" target="_blank">#chaos</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/elasticity/" target="_blank">#elasticity</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/solid-mechanics/" target="_blank">#solidMechanics</a>

Nicole SharpReclaiming the LandLava floods human-made infrastructure on Iceland’s Reykjanes peninsula in this aerial image from photographer Ael Kermarec. Protecting roads and buildings from lava flows is a formidable challenge, but it’s one that researchers are tackling. But the larger and faster the lava flow, the harder infrastructure is to protect. Sometimes our best efforts are simply overwhelmed by nature’s power. (Image credit: <a href="https://www.worldnaturephotographyawards.com/winners-2025" rel="nofollow noopener noreferrer" target="_blank">A. Kermarec/WNPA</a>; via <a href="https://www.thisiscolossal.com/2025/03/2025-world-nature-photography-awards/?__readwiseLocation=" rel="nofollow noopener noreferrer" target="_blank">Colossal</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluids-as-art/" target="_blank">#fluidsAsArt</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/geophysics/" target="_blank">#geophysics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/gravity-current/" target="_blank">#gravityCurrent</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/lava/" target="_blank">#lava</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/viscous-flow/" target="_blank">#viscousFlow</a>

Nicole SharpThawing Permafrost Primes SlumpsAs permafrost thaws on Arctic hillsides and shorelines, the land often deforms in a unique fashion, known as a slump. Formally known as mega retrogressive thaw slumps, these areas superficially resemble a landslide. They’re also prone to repeat performances: as many as 90% of Canada’s Arctic slumps recur in the same place as previous slumps. <a href="https://doi.org/10.1029/2023JF007556" rel="nofollow noopener noreferrer" target="_blank">Researchers used</a> ground-penetrating radar and other tools to study the underground structure at slumps and found that several factors contribute to this repetitive cycle.Seawater soaking into the foot of a hilly shore can destabilize the permafrost, creating a slump. That changes the nearby ground cover, exposing more permafrost to warming; their measurements showed this warming could extend tens of meters underground, priming the area for future slumps. Similarly, the mudslides and narrow ravines that form on an active slump also shift away ground cover and warm the underlying permafrost. Together, these factors suggest that once a slump forms, more slumps will occur as the underlying permafrost warms. (Image credit: M. Krautblatter; research credit: <a href="https://doi.org/10.1029/2023JF007556" rel="nofollow noopener noreferrer" target="_blank">M. Krautblatter et al.</a>; via <a href="https://eos.org/research-spotlights/down-in-the-slumps-tracing-erosion-cycles-in-arctic-permafrost" rel="nofollow noopener noreferrer" target="_blank">Eos</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/erosion/" target="_blank">#erosion</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/geophysics/" target="_blank">#geophysics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/granular-material/" target="_blank">#granularMaterial</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/slump/" target="_blank">#slump</a>

Nicole SharpTwisting in the Flow <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/liqcrys1.png" rel="nofollow noopener noreferrer" target="_blank"></a> <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/liqcrys2.png" rel="nofollow noopener noreferrer" target="_blank"></a> <a class="" href="https://fyfluiddynamics.com/wp-content/uploads/liqcrys3.png" rel="nofollow noopener noreferrer" target="_blank"></a> What happens to liquid crystals in a flow? In this video, researchers look at liquid crystals flowing through the narrow gap of a microfluidic device. Initially, all the crystals are oriented the same way, as if they are logs rolling down a river. But as the flow rate increases, narrow lines appear in the flow, followed by disordered regions, and, eventually, a new configuration: vertical bands streaking the left-to-right flow. The colors, in this case, indicate the orientation of the liquid crystals. As the researchers show, the crystals collectively twist to form the spontaneous bands. (Video and image credit: <a href="https://doi.org/10.1103/APS.DFD.2024.GFM.V2685277" rel="nofollow noopener noreferrer" target="_blank">D. Jia and I. Bischofberger</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/2024gofm/" target="_blank">#2024gofm</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/flow-visualization/" target="_blank">#flowVisualization</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/instability/" target="_blank">#instability</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/liquid-crystals/" target="_blank">#liquidCrystals</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a>

Nicole SharpSimulating a SneezeSneezing 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 <a href="https://doi.org/10.1063/5.0241346" rel="nofollow noopener noreferrer" target="_blank">“sneeze simulator”</a> 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: <a href="https://doi.org/10.1063/5.0241346" rel="nofollow noopener noreferrer" target="_blank">N. Catalán et al.</a>; via <a href="https://physicsworld.com/a/sneeze-simulator-could-improve-predictions-of-pathogen-spread/" rel="nofollow noopener noreferrer" target="_blank">Physics World</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/aerosols/" target="_blank">#aerosols</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/biology/" target="_blank">#biology</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/coughing/" target="_blank">#coughing</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/covid-19/" target="_blank">#COVID19</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/disease-transmission/" target="_blank">#diseaseTransmission</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/droplets/" target="_blank">#droplets</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/flow-visualization/" target="_blank">#flowVisualization</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/sneezing/" target="_blank">#sneezing</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/turbulence/" target="_blank">#turbulence</a>

Nicole SharpGrowing IceWhile much attention is given to the summer loss of sea ice, the birth of new ice in the fall is also critical. Ice loss in the summer leaves oceans warmer and waves larger since wind can blow across longer open stretches. Those warmer waters and more dynamic waves affect how ice forms once autumn sets in. Higher waves mean that ice tends to form in “pancakes” like those seen here. Pancake ice is small — typically under 1 meter wide — and can only be observed from nearby, since they’re smaller than typical satellite resolution. Only once there’s enough pancake ice to dampen the waves will the pieces begin to cement together to form larger pieces that will form the basis of the year’s new ice. (Image credit: <a href="https://blogs.egu.eu/divisions/cr/2018/04/27/image-of-the-week-making-pancakes/" rel="nofollow noopener noreferrer" target="_blank">M. Smith</a>; see also <a href="https://eos.org/science-updates/the-balance-of-ice-waves-and-winds-in-the-arctic-autumn?__readwiseLocation=" rel="nofollow noopener noreferrer" target="_blank">Eos</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/ice-formation/" target="_blank">#iceFormation</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/oceanography/" target="_blank">#oceanography</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/pancake-ice/" target="_blank">#pancakeIce</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/planetary-science/" target="_blank">#planetaryScience</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/sea-ice/" target="_blank">#seaIce</a>

N-gated Hacker News🧠⚡ "Quanta Magazine unravels the 'mystery' of brain fluid flow, because who doesn't love a good brain fluid saga? Spoiler: it's just more fluid <a href="https://mastodon.social/tags/dynamics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#dynamics</a> but with a touch of biological jargon to sound fancy. 🧩📚" <a href="https://www.quantamagazine.org/the-mysterious-flow-of-fluid-in-the-brain-20250326/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.quantamagazine.org/the-mysterious-flow-of-fluid-in-the-brain-20250326/</a> <a href="https://mastodon.social/tags/brainfluid" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#brainfluid</a> <a href="https://mastodon.social/tags/biologicalresearch" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#biologicalresearch</a> <a href="https://mastodon.social/tags/QuantaMagazine" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QuantaMagazine</a> <a href="https://mastodon.social/tags/sciencecommunication" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#sciencecommunication</a> <a href="https://mastodon.social/tags/fluiddynamics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#fluiddynamics</a> <a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#HackerNews</a> <a href="https://mastodon.social/tags/ngated" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#ngated</a>

Nicole Sharp“Visions in Ice”The glittering blue interior of an ice cave sparkles in this award-winning image by photographer Yasmin Namini. The cave is underneath Iceland’s Vatnajokull Glacier. Notice the deep scallops carved into the lower wall. This shape is common in melting and dissolution processes. It is unavoidable for flat surfaces exposed to a melting/dissolving flow. (Image credit: <a href="https://www.worldnaturephotographyawards.com/winners-2025" rel="nofollow noopener noreferrer" target="_blank">Y. Namini</a>/WNPA; via <a href="https://www.thisiscolossal.com/2025/03/2025-world-nature-photography-awards/?__readwiseLocation=" rel="nofollow noopener noreferrer" target="_blank">Colossal</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/erosion/" target="_blank">#erosion</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluids-as-art/" target="_blank">#fluidsAsArt</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/geology/" target="_blank">#geology</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/geophysics/" target="_blank">#geophysics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/glacier/" target="_blank">#glacier</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/ice/" target="_blank">#ice</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/instability/" target="_blank">#instability</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/melting/" target="_blank">#melting</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a>

Nicole SharpCrowd VorticesThe Feast of San Fermín in Pamplona, Spain draws crowds of thousands. <a href="https://doi.org/10.1038/s41586-024-08514-6" rel="nofollow noopener noreferrer" target="_blank">Scientists recently published</a> an analysis of the crowd motion in these dense gatherings. The team filmed the crowds at the festival from balconies overlooking the plaza in 2019, 2022, 2023, and 2024. Analyzing the footage, they discovered that at crowd densities above 4 people per square meter, the crowd begins to move in almost imperceptible eddies. In the animation below, lines trace out the path followed by single individuals in the crowd, showing the underlying “vortex.” At the plaza’s highest density — 9 people per square meter — one rotation of the vortex took about 18 seconds. The team found similar patterns in footage of the crowd at the 2010 Love Parade disaster, in which 21 people died. These patterns aren’t themselves an indicator of an unsafe crowd — none of the studied Pamplona crowds had a problem — but understanding the underlying dynamics should help planners recognize and prevent dangerous crowd behaviors before the start of a stampede. (Image credit: still – <a href="https://unsplash.com/photos/people-on-gray-concrete-66BEYHtoWYY" rel="nofollow noopener noreferrer" target="_blank">San Fermín</a>, animation – Bartolo Lab; research credit: <a href="https://doi.org/10.1038/s41586-024-08514-6" rel="nofollow noopener noreferrer" target="_blank">F. Gu et al.</a>; via <a href="https://www.nature.com/articles/d41586-025-00373-z?linkId=12807715&__readwiseLocation" rel="nofollow noopener noreferrer" target="_blank">Nature</a>)<a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/active-matter/" target="_blank">#activeMatter</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/collective-motion/" target="_blank">#collectiveMotion</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/crowds/" target="_blank">#crowds</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/fluid-dynamics/" target="_blank">#fluidDynamics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/physics/" target="_blank">#physics</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/science/" target="_blank">#science</a> <a rel="nofollow noopener noreferrer" class="hashtag u-tag u-category" href="https://fyfluiddynamics.com/tagged/vortices/" target="_blank">#vortices</a>

Hacker NewsThe Mysterious Flow of Fluid in the Brain<a href="https://www.quantamagazine.org/the-mysterious-flow-of-fluid-in-the-brain-20250326/" rel="nofollow noopener noreferrer" translate="no" target="_blank">https://www.quantamagazine.org/the-mysterious-flow-of-fluid-in-the-brain-20250326/</a><a href="https://mastodon.social/tags/HackerNews" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#HackerNews</a> <a href="https://mastodon.social/tags/MysteriousBrainFlow" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#MysteriousBrainFlow</a> <a href="https://mastodon.social/tags/FluidDynamics" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#FluidDynamics</a> <a href="https://mastodon.social/tags/Neuroscience" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#Neuroscience</a> <a href="https://mastodon.social/tags/QuantaMagazine" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#QuantaMagazine</a> <a href="https://mastodon.social/tags/BrainResearch" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#BrainResearch</a>

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