{"id":5762,"date":"2026-05-14T09:46:11","date_gmt":"2026-05-14T13:46:11","guid":{"rendered":"https:\/\/engineering.jhu.edu\/lefd\/?page_id=5762"},"modified":"2026-05-14T11:23:05","modified_gmt":"2026-05-14T15:23:05","slug":"rough-wall-boundary-layer","status":"publish","type":"page","link":"https:\/\/engineering.jhu.edu\/lefd\/rough-wall-boundary-layer\/","title":{"rendered":"Rough wall boundary layer"},"content":{"rendered":"<h1>People<\/h1>\n<ul>\n<li>Deepan Sharma<\/li>\n<li>Jian Gao (Former Postdoc)<\/li>\n<\/ul>\n<h1>Objectives<\/h1>\n<ul>\n<li style=\"text-align: left;\">All turbulent wall-bounded flows of practical interest involve dynamically relevant roughness.<\/li>\n<li>Some of these involve compliant surfaces and may feature two-way coupling with the boundary layer.<\/li>\n<li>Most existing modelling tools do not resolve the flow near the wall.<\/li>\n<li>There is a paucity of experimental data around the roughness despite their relevance to important phenomena \u2013 e.g. noise production (fluctuating wall pressure, WSS, and forces on roughness elements)<\/li>\n<li style=\"text-align: left;\">Recent advances in measurement capability at JHU have made it possible to fully resolve velocity, pressure, and forces generated by individual roughness elements<\/li>\n<\/ul>\n<h1>Current work<\/h1>\n<p style=\"text-align: left;\">Work done:<\/p>\n<p style=\"text-align: left;\">(i) 3D\u00a0 mean flow field (ii) vortical structures (iii) Reynolds, (iv) shear stress distribution, (v) pressure field\u00a0 focused around the element and\u00a0 (vi) mean hydrodynamic force on the cylinder (vii) contributions of viscous and form drag on total drag for friction based Reynolds number of 2120<\/p>\n<p style=\"text-align: left;\">Ongoing work:<\/p>\n<p>Perform fully resolved (space + time) volumetric measurements of velocity\/pressure\/form drag within the roughness canopy of TBLs<\/p>\n<ul>\n<li>Obtain low-frequency (at least) time-resolved wall shear stress (WSS) measurements<\/li>\n<li>Calculate the unsteady pressure field, and hence unsteady forces on the roughness element by integrating the pressure distribution around it.<\/li>\n<\/ul>\n<h1>Facility<\/h1>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-5876 aligncenter\" src=\"https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-300x169.png\" alt=\"\" width=\"837\" height=\"472\" srcset=\"https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-300x169.png 300w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-1024x576.png 1024w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-200x113.png 200w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-768x432.png 768w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-1536x864.png 1536w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-2048x1152.png 2048w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-150x84.png 150w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide-320x180.png 320w\" sizes=\"auto, (max-width: 837px) 100vw, 837px\" \/><\/p>\n<h1>Results<\/h1>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-5891 aligncenter\" src=\"https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-300x169.png\" alt=\"\" width=\"847\" height=\"477\" srcset=\"https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-300x169.png 300w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-1024x576.png 1024w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-200x113.png 200w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-768x432.png 768w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-1536x864.png 1536w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-2048x1152.png 2048w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-150x84.png 150w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide2-320x180.png 320w\" sizes=\"auto, (max-width: 847px) 100vw, 847px\" \/><\/p>\n<h1>Ongoing rough wall work (DARPA)<\/h1>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-5897 aligncenter\" src=\"https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-300x169.png\" alt=\"\" width=\"839\" height=\"473\" srcset=\"https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-300x169.png 300w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-1024x576.png 1024w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-200x113.png 200w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-768x432.png 768w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-1536x864.png 1536w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-2048x1152.png 2048w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-150x84.png 150w, https:\/\/engineering.jhu.edu\/lefd\/wp-content\/uploads\/2026\/05\/Deepan_roughwall_slide3-320x180.png 320w\" sizes=\"auto, (max-width: 839px) 100vw, 839px\" \/><\/p>\n<h1>Previous results<\/h1>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<h3><\/h3>\n","protected":false},"excerpt":{"rendered":"<p>People Deepan Sharma Jian Gao (Former Postdoc) Objectives All turbulent wall-bounded flows of practical interest involve dynamically relevant roughness. Some of these involve compliant surfaces and may feature two-way coupling with the boundary layer. Most existing modelling tools do not &hellip; <a href=\"https:\/\/engineering.jhu.edu\/lefd\/rough-wall-boundary-layer\/\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":7627,"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-5762","page","type-page","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.7 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Rough wall boundary layer - Laboratory for Experimental Fluid Dynamics<\/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\/lefd\/rough-wall-boundary-layer\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Rough wall boundary layer - Laboratory for Experimental Fluid Dynamics\" \/>\n<meta property=\"og:description\" content=\"People Deepan Sharma Jian Gao (Former Postdoc) Objectives All turbulent wall-bounded flows of practical interest involve dynamically relevant roughness. 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