{"id":169087,"date":"2025-09-25T22:48:11","date_gmt":"2025-09-25T22:48:11","guid":{"rendered":"https:\/\/www.newsbeep.com\/au\/169087\/"},"modified":"2025-09-25T22:48:11","modified_gmt":"2025-09-25T22:48:11","slug":"now-arriving-a-new-theory-of-in-flight-turbulence","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/au\/169087\/","title":{"rendered":"Now Arriving, a New Theory of In-Flight Turbulence"},"content":{"rendered":"<p class=\"css-at9mc1 evys1bk0\">Bjorn Birnir dreads an airplane seatmate asking what he does for a living. That\u2019s because Dr. Birnir is one of the world\u2019s leading scholars of turbulence, the chaotic movement of fluids, such as water or air, in the midst of a disturbance. Inevitably, the seatmate will ask Dr. Birnir the one question he knows is coming and is loath to answer: Just how dangerous is turbulence, anyway?<\/p>\n<p class=\"css-at9mc1 evys1bk0\">These days, that question is being asked with increasing frequency by the <a class=\"css-yywogo\" href=\"https:\/\/www.faa.gov\/air_traffic\/by_the_numbers\" title=\"\" rel=\"noopener noreferrer nofollow\" target=\"_blank\">three million people<\/a> who fly each day in and out of American airports alone. Once seemingly relegated to a background annoyance of commercial aviation, like bad food and insufficient leg room, severe turbulence is only getting worse. In 2023, British researchers used meteorological data gathered over several decades to arrive at the conclusion that severe turbulence over the North Atlantic had <a class=\"css-yywogo\" href=\"https:\/\/agupubs.onlinelibrary.wiley.com\/doi\/10.1029\/2023GL103814\" title=\"\" rel=\"noopener noreferrer nofollow\" target=\"_blank\">increased by 55 percent<\/a> between 1979 and 2020. (The study looked only at clear-air turbulence, which occurs when a plane isn\u2019t flying through a storm or above a mountain range; that kind of turbulence is especially difficult to predict.)<\/p>\n<p class=\"css-at9mc1 evys1bk0\">\u201cI have thought many times that it would be wonderful if we could make air travel a little more pleasant,\u201d said Dr. Birnir, who runs the Center for Complex and Nonlinear Science at the University of California, Santa Barbara, and also chairs the mathematics department there. His latest contribution to that effort is <a class=\"css-yywogo\" href=\"https:\/\/journals.aps.org\/prresearch\/abstract\/10.1103\/PhysRevResearch.7.023225\" title=\"\" rel=\"noopener noreferrer nofollow\" target=\"_blank\">a recent paper in the scientific journal Physical Review Research<\/a> that he said presented arguably the most advanced model of turbulent motion. This model could, in turn, help engineers who strive to make flight safer and less stressful.<\/p>\n<p class=\"css-at9mc1 evys1bk0\">\u201cAirplane design is going to benefit,\u201d Dr. Birnir said. \u201cWe should definitely see better meteorological models.\u201d<\/p>\n<p class=\"css-at9mc1 evys1bk0\">Thomas Q. Carney, a retired professor of aviation technology at Purdue University who has logged more than 11,000 flight hours as a pilot, said, \u201cThe better the model, the more it captures of the particular turbulent field, then the better the forecast, which is what the pilot is going to use.\u201d<\/p>\n<p class=\"css-at9mc1 evys1bk0\">Flying on American carriers <a class=\"css-yywogo\" href=\"https:\/\/www.nytimes.com\/2025\/02\/18\/travel\/plane-crashes-flight-safety.html\" title=\"\" rel=\"nofollow noopener\" target=\"_blank\">remains exceptionally safe<\/a>, but recent accidents have started to erode confidence in commercial aviation. This month, the National Transportation Safety Board <a class=\"css-yywogo\" href=\"https:\/\/www.nytimes.com\/interactive\/2025\/09\/10\/us\/ntsb-report-dl56.html\" title=\"\" rel=\"nofollow noopener\" target=\"_blank\">released an interim report<\/a> on a Delta Air Lines flight that injured several people during an encounter in late July with unexpectedly rough air over Wyoming. The pilots had sought to avoid bad weather, <a class=\"css-yywogo\" href=\"https:\/\/www.nytimes.com\/2025\/09\/10\/us\/politics\/delta-turbulence-ntsb.html\" title=\"\" rel=\"nofollow noopener\" target=\"_blank\">only to unexpectedly get tossed about by turbulent flows.<\/a> (<a class=\"css-yywogo\" href=\"https:\/\/www.nytimes.com\/2025\/06\/13\/climate\/air-travel-extreme-heat.html\" title=\"\" rel=\"nofollow noopener\" target=\"_blank\">Climate change<\/a> may also be having an effect, since a warming atmosphere affects air pressure and wind speed.)<\/p>\n<p class=\"css-at9mc1 evys1bk0\">Turbulence has long posed a challenge to scientists, although researchers in recent years have made significant changes in understanding how turbulence works. Richard P. Feynman, a Nobel Prize-winning physicist, once called it \u201cthe most important unsolved problem of classical physics.\u201d One reason is that turbulence \u201cis based on so many moving parts, so to speak \u2014 temperature, pressure, wind, et cetera,\u201d said Patrick Smith, who writes about aviation on his website, <a class=\"css-yywogo\" href=\"https:\/\/askthepilot.com\/\" title=\"\" rel=\"noopener noreferrer nofollow\" target=\"_blank\">Ask the Pilot<\/a>. \u201cThe factors and conditions that cause rough air can change very quickly.\u201d<\/p>\n<p class=\"css-at9mc1 evys1bk0\">The system is inherently chaotic, refusing to evolve along a predictable path. Particles undergoing turbulent motion \u201cstart to diverge in different directions,\u201d said Tanner D. Harms, who studied turbulence as a doctoral student at the California Institute of Technology. Those directions are exceptionally difficult to model accurately. \u201cThe definition of chaos is almost woven into turbulence itself.\u201d<\/p>\n<p class=\"css-at9mc1 evys1bk0\">To try to make sense of chaos, Dr. Birnir worked with Luiza Angheluta-Bauer, a theoretical physicist at the University of Oslo, to devise a model that combines two different methods for observing turbulence: what are known as Lagrangian and Eulerian mechanics. Experts say that neither framework can fully explain on its own how turbulence works.<\/p>\n<p class=\"css-at9mc1 evys1bk0\">That\u2019s because these two frameworks look at fundamentally different aspects of a turbulent system. In Lagrangian mechanics, researchers observe a simple particle, while in the Eulerian framework they look at a single point in space. Put simply, Lagrangian mechanics is like watching a leaf flow downriver, subject to the whims of eddies in the water. On the other hand, Eulerian mechanics is like watching a rock that protrudes from the river\u2019s surface and studying how the turbulence of the water moves around that fixed point.<\/p>\n<p class=\"css-at9mc1 evys1bk0\">Lagrangian turbulence is trickier to model because it requires an understanding of how a lone particle will behave. That lone particle will \u201cexecute the most complicated motion that you could imagine,\u201d Dr. Birnir said.<\/p>\n<p class=\"css-at9mc1 evys1bk0\">Knowing how each type of turbulence fits into the bigger picture is akin to selecting the appropriate lens for a microscope, since both are highly dependent on perspective. \u201cSame turbulence, different stories,\u201d said Tomek Jaroslawski, a postdoctoral fellow at the Center of Turbulence Research at Stanford. \u201cNeither view is wrong \u2014 they\u2019re just different ways of asking nature a question.\u201d<\/p>\n<p class=\"css-at9mc1 evys1bk0\">He and Dr. Angheluta-Bauer used both theoretical and statistical approaches. Previously, physicists had not managed to come up with such a comprehensive model of turbulent motion. \u201cThe result is novel, there is no doubt about that,\u201d said Katepalli Sreenivasan, a former dean of the Tandon School of Engineering at New York University, acknowledging that some experts disagreed with his assessment.<\/p>\n<p class=\"css-at9mc1 evys1bk0\">\u201cFully developed turbulence is where things are just crazy,\u201d said J. Doyne Farmer, a professor of complex and chaotic systems at the University of Oxford. \u201cThose eddies are behaving very chaotically, and there are many degrees of freedom.\u201d<\/p>\n<p class=\"css-at9mc1 evys1bk0\">Dr. Birnir said he believed that the Delta flight over Wyoming \u201cseems to be a typical example of severe intermittency in Eulerian turbulence,\u201d although he said that he couldn\u2019t make a definitive analysis without access to the raw data. He said that a more nuanced model of turbulence model might have allowed the pilots to take preventive measures, such as reducing engine power, to counter the Eulerian irregularity they were flying through.<\/p>\n<p class=\"css-at9mc1 evys1bk0\">Dr. Carney, of Purdue University, confessed that some of the work that Dr. Birnir and Dr. Angheluta-Bauer had done was beyond him and would probably be beyond the grasp of any pilot without expertise in computational fluid dynamics. But that did not diminish its potential utility. \u201cI feel confident that they are adding to the state of knowledge,\u201d he said.<\/p>\n","protected":false},"excerpt":{"rendered":"Bjorn Birnir dreads an airplane seatmate asking what he does for a living. That\u2019s because Dr. Birnir is&hellip;\n","protected":false},"author":2,"featured_media":169088,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[110671,64,63,64408,4359,110672,292,77246,128],"class_list":["post-169087","post","type-post","status-publish","format-standard","has-post-thumbnail","category-physics","tag-airlines-and-airplanes","tag-au","tag-australia","tag-delta-air-lines-inc","tag-global-warming","tag-national-transportation-safety-board","tag-physics","tag-pilots","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/169087","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=169087"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/169087\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/169088"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=169087"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=169087"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=169087"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}