{"id":30,"date":"2013-10-09T13:48:59","date_gmt":"2013-10-09T17:48:59","guid":{"rendered":"https:\/\/engineering.jhu.edu\/zaki\/?page_id=30"},"modified":"2022-09-04T16:06:10","modified_gmt":"2022-09-04T20:06:10","slug":"research","status":"publish","type":"page","link":"https:\/\/engineering.jhu.edu\/zaki\/research\/","title":{"rendered":"Research"},"content":{"rendered":"

<\/h2>\n\n\n\n
\"Lambdas_BL\"<\/a><\/td>\n\n

Transition<\/a><\/h2>\n

In many fluid flows, transition of boundary layers from laminar to turbulence is forced by free-stream perturbations.\u00a0This phenomenon is called Bypass Transition. In this project, the mechanics of bypass transition are investigated using direct numerical simulations and stability theory.\u00a0The influence of a full spectrum of perturbations, and also\u00a0particular vortical modes, on boundary layer stability are investigated.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/h2>\n\n\n\n
\n

Data assimilation <\/a>
\nand measurements-infused simulations<\/a><\/h2>\n

Simulations of transition and turbulence provide non-intrusive access to all flow quantities, although they introduce idealizations and modeling assumptions that can compromise their accuracy. In contrast, experiments are less idealized but measurements must contend with sensor limitations. \u00a0By directly infusing measurement data into our simulations, we synergistically enhance the realism of the simulations and augment the resolution of the physical measurements.<\/td>\n

\"Data<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/h2>\n\n\n\n
\n

Physics-based machine learning<\/a><\/h2>\n

Our group develops machine-learning algorithms to solve challenging fluid dynamical problems. \u00a0Our algorithms are predictive, seamlessly integrate data and physical laws, and have been applied to a wide range of problems including transitional shear flows, turbulence, and \u00a0hypersonic flows.<\/td>\n

\"\"<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/h2>\n\n\n\n
\"visco_spot\"<\/a><\/td>\n\n

Viscoelasticy<\/a><\/h2>\n

Viscoelastic fluids often behave in a manner that defies our fluid dynamical intuition. \u00a0For example, they can sustain a chaotic flow state even in the limit of vanishing Reynolds numbers, and in the opposite limit of\u00a0high Reynolds numbers they can significantly tame\u00a0turbulence and reduce drag. \u00a0In this project, we examine\u00a0the evolution of disturbances in viscoelastic fluids across flow regimes. When intriguing new dynamics are observed, we provide the\u00a0theory to explain the role of elasticity.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/h2>\n\n\n\n
\n

Turbomachinery<\/a><\/h2>\n

Under adverse pressure gradient conditions, boundary layers can undergo separation, thus significantly increasing viscous losses and reducing lift. In turbomachinery, for example, it\u00a0is desirable to delay or completely suppress separation.
\nIn this project, the flow through a compressor passage is computed using DNS, and the influence of the free-stream turbulence on the suction and pressure surface boundary layers are contrasted.<\/td>\n

\"Blade_ColorNew\"<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/h2>\n\n\n\n
\n

Two-fluid shear flows<\/a><\/h2>\n

The stability characteristics of two-fluid flows are significantly affected by the presence of the two-fluid interface.\u00a0Interfacial waves, as well as other types of instability modes may arise and lead to deformation of the interface, the formation of interfacial ligaments, and droplet breakup and entrainment.
\nIn this project, we investigate the instability of two-phase film flows using analytical techniques and DNS.<\/td>\n

\"Waves\"<\/a><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

<\/h2>\n\n\n\n
\"Throat<\/a><\/td>\n\n

Bio-flows: <\/a>Inhaled-drug delivery<\/a><\/h2>\n

The flow and the transport of particles in the human respiratory system dictate the effectiveness of therapeutic aerosols used in inhaled drug delivery.\u00a0 Therefore, knowledge of the particle deposition in the mouth\/throat region is critical in the design of effective inhalation devices for optimum delivery to the lungs.In collaboration with GlaxoSmithKline, we are developing validated numerical simulations techniques for flow and particle deposition in the upper respiratory tract.\u00a0 These methods offer a non-invasive and cost-effective alternative to in vivo and in vitro tests.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":"

Transition In many fluid flows, transition of boundary layers from laminar to turbulence is forced by free-stream perturbations.\u00a0This phenomenon is called Bypass Transition. In this project, the mechanics of bypass transition are investigated using direct numerical simulations and stability theory.\u00a0The influence of a full spectrum of perturbations, and also\u00a0particular vortical modes, on boundary layer stability […]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"class_list":["post-30","page","type-page","status-publish","hentry"],"yoast_head":"\nResearch - Flow Science and Engineering<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/engineering.jhu.edu\/zaki\/research\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Research - Flow Science and Engineering\" \/>\n<meta property=\"og:description\" content=\"Transition In many fluid flows, transition of boundary layers from laminar to turbulence is forced by free-stream perturbations.\u00a0This phenomenon is called Bypass Transition. In this project, the mechanics of bypass transition are investigated using direct numerical simulations and stability theory.\u00a0The influence of a full spectrum of perturbations, and also\u00a0particular vortical modes, on boundary layer stability […]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/engineering.jhu.edu\/zaki\/research\/\" \/>\n<meta property=\"og:site_name\" content=\"Flow Science and Engineering\" \/>\n<meta property=\"article:modified_time\" content=\"2022-09-04T20:06:10+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/engineering.jhu.edu\/zaki\/wp-content\/uploads\/2014\/10\/Lambdas_BL-300x247.jpg\" \/>\n<meta name=\"twitter:label1\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data1\" content=\"4 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/\",\"url\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/\",\"name\":\"Research - Flow Science and Engineering\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/wp-content\\\/uploads\\\/2014\\\/10\\\/Lambdas_BL-300x247.jpg\",\"datePublished\":\"2013-10-09T17:48:59+00:00\",\"dateModified\":\"2022-09-04T20:06:10+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/#primaryimage\",\"url\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/wp-content\\\/uploads\\\/2014\\\/10\\\/Lambdas_BL.jpg\",\"contentUrl\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/wp-content\\\/uploads\\\/2014\\\/10\\\/Lambdas_BL.jpg\",\"width\":1002,\"height\":828},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/research\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Research\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/#website\",\"url\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/\",\"name\":\"Flow Science and Engineering\",\"description\":\"Tamer Zaki's Research Group\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/engineering.jhu.edu\\\/zaki\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Research - Flow Science and Engineering","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/engineering.jhu.edu\/zaki\/research\/","og_locale":"en_US","og_type":"article","og_title":"Research - Flow Science and Engineering","og_description":"Transition In many fluid flows, transition of boundary layers from laminar to turbulence is forced by free-stream perturbations.\u00a0This phenomenon is called Bypass Transition. 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