{"id":3745,"date":"2025-04-18T08:51:16","date_gmt":"2025-04-18T13:51:16","guid":{"rendered":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/?post_type=tribe_events&p=3745"},"modified":"2025-04-18T11:14:15","modified_gmt":"2025-04-18T16:14:15","slug":"lans-seminar-166","status":"publish","type":"tribe_events","link":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/event\/lans-seminar-166\/","title":{"rendered":"LANS Seminar"},"content":{"rendered":"

Seminar Title:\u00a0 <\/strong>Towards a New School in Aerodynamics: Fluid Mechanics as a Minimization Problem<\/p>\n

Speaker: <\/strong>Haithem\u00a0Taha,\u00a0Professor, Department of Mechanical and Aerospace\u00a0Engineering, University of California, Irvine.<\/p>\n

Date\/Time:<\/strong> Thursday, April 24, 2025\/ 2:30 PM \u2013 3:30 PM (In-Person)
\nLocation:\u00a0<\/strong>See Meeting URL on the cels-seminars website which will require an Argonne login.<\/em><\/p>\n

Description: <\/strong>Driven by an outdated problem in aerodynamics, we\u00a0discovered a new principle\u00a0in fluid physics. The\u00a0Euler\u00a0equation does not possess a unique solution for the\u00a0flow over a multiply connected domain. This problem has serious repercussions in aerodynamics; it implies that the\u00a0inviscid aero-hydrodynamic lift force\u00a0over a two-dimensional object cannot be\u00a0determined from first principles; a closure condition must be\u00a0provided. The\u00a0Kutta condition has been ubiquitously considered for such a closure\u00a0in the literature,\u00a0even in cases where\u00a0it is not applicable.\u00a0 In this talk, I will present a special variational principle\u00a0in analytical mechanics: Gauss\u2019s principle of least constraint. We extended this principle to the continuum mechanics of incompressible flows, resulting in the\u00a0Principle\u00a0of Minimum Pressure\u00a0Gradient (PMPG).\u00a0 The principle asserts that the\u00a0magnitude\u00a0of the\u00a0pressure\u00a0gradient over the\u00a0field is minimum at\u00a0every instant!\u00a0 We proved that a candidate smooth flow field is a solution of Navier-Stokes if and only if<\/em><\/strong> its evolution minimizes the L2 norm of the pressure gradient at every instant of time. Hence, the PMPG turns a fluid mechanics problem into a minimization one\u00a0where\u00a0fluid mechanicians need not to apply Navier-Stokes\u2019\u00a0equations, but minimize\u00a0the pressure\u00a0gradient cost. In this talk, I will discuss this fresh view of fluid mechanics as a minimizing problem. Applying this new variational formulation to the century-old problem of the\u00a0ideal flow over an airfoil, we developed a general (dynamical) closure\u00a0condition that is, unlike\u00a0the\u00a0Kutta condition, derived from first principles. In contrast to the\u00a0classical theory, the proposed variational theory is not confined to sharp\u00a0edged airfoils; i.e., it allows, for the\u00a0first time, theoretical computation of lift over arbitrarily smooth shapes, thereby generalizing the\u00a0century-old lift theory of Kutta and Zhukovsky. The PMPG also allowed prediction of separation over a cylinder in the subcritical regime (where characteristics are independent of viscosity) solely from the outer flow without boundary layer calculation\u2014a task that was deemed impossible. I will also discuss developing computational simulations using this variational formulation, which allows explicit projection of Navier-Stokes without the need to solve the Poisson equation in pressure at every time step, thereby avoiding the most expensive step in computational simulations.<\/p>\n

Bio: <\/strong>Haithem\u00a0Taha\u00a0is currently a professor in the\u00a0department of Mechanical and Aerospace\u00a0Engineering at the\u00a0University of California, Irvine. He received a PhD\u00a0from Virginia Tech simultaneously with an MSc degree\u00a0in Mathematics.\u00a0Taha\u2019s research interests span unsteady\u00a0aerodynamics, theoretical mechanics\u00a0 and\u00a0 variational principles, and differential\u00a0geometric\u00a0 mechanics and control\u00a0with\u00a0 applications\u00a0 to unconventional\u00a0 flight mechanics such as bio-inspired flight. He\u00a0is a Recipient of the\u00a0NSF CAREER Award among several other awards. He\u00a0is an AIAA Associate\u00a0Fellow.\u00a0Taha\u00a0is particularly interested in the\u00a0history and philosophy of mechanics and has several lectures on the\u00a0topic.<\/p>\n

Please note that the meeting URL for this event can be seen on the cels-seminars website which requires an Argonne login.<\/em><\/p>\n

\n

See all upcoming talks at\u00a0https:\/\/www.anl.gov\/mcs\/lans-seminars<\/a><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Seminar Title:\u00a0 Towards a New School in Aerodynamics: Fluid Mechanics as a Minimization Problem Speaker: Haithem\u00a0Taha,\u00a0Professor, Department of Mechanical and Aerospace\u00a0Engineering, University of California, Irvine. Date\/Time: Thursday, April 24, 2025\/ 2:30 PM \u2013 3:30 PM (In-Person) Location:\u00a0See Meeting URL on … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":976,"featured_media":0,"template":"","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_tribe_events_status":"","_tribe_events_status_reason":"","footnotes":""},"tags":[],"tribe_events_cat":[2],"class_list":["post-3745","tribe_events","type-tribe_events","status-publish","hentry","tribe_events_cat-seminar","cat_seminar"],"acf":[],"_links":{"self":[{"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/tribe_events\/3745","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/tribe_events"}],"about":[{"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/types\/tribe_events"}],"author":[{"embeddable":true,"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/users\/976"}],"version-history":[{"count":3,"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/tribe_events\/3745\/revisions"}],"predecessor-version":[{"id":3750,"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/tribe_events\/3745\/revisions\/3750"}],"wp:attachment":[{"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/media?parent=3745"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/tags?post=3745"},{"taxonomy":"tribe_events_cat","embeddable":true,"href":"https:\/\/wordpress.cels.anl.gov\/lans-seminars\/wp-json\/wp\/v2\/tribe_events_cat?post=3745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}