{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,22]],"date-time":"2025-11-22T05:19:15Z","timestamp":1763788755526,"version":"3.45.0"},"reference-count":48,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2025,11,20]],"date-time":"2025-11-20T00:00:00Z","timestamp":1763596800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>The riblet surface is a passive turbulence drag reduction technology with promising aerospace application prospects. To investigate the drag reduction effects of riblets under flow conditions more representative of actual aircraft surfaces, this study establishes an adverse pressure gradient environment at moderate-to-high Reynolds numbers. Symmetrically arranged two testing plates with riblets\u2019 surface and smooth surface, hot-wire anemometry is employed to measure the skin friction drag of both plates to get a direct measurement of the drag reduction rate. And the drag reduction mechanism is analyzed through burst events detection and coherent structure\u2019s inclination angle. The measurement results indicate that the adverse pressure gradient itself leads to a reduction in wall friction, and the turbulent boundary layer velocity profile deviates from the standard logarithmic law, rendering the Clauser chart method unsuitable for estimating the friction velocity. The adverse pressure gradient contributes positively to the drag reduction rate of riblets, while the increase in Reynolds number in this experiment has no substantial effect. For the near wall structures, their asymmetrical movement of ejection and sweep and investigated by VITA. The significant decrease in burst frequency and increase in coherent structure inclination angle in the turbulent boundary layer over the riblet surface are identified as the primary reasons for reduced wall friction, with these changes being particularly pronounced under adverse pressure gradient conditions.<\/jats:p>","DOI":"10.3390\/sym17112007","type":"journal-article","created":{"date-parts":[[2025,11,20]],"date-time":"2025-11-20T09:44:53Z","timestamp":1763631893000},"page":"2007","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Influence of Adverse Pressure Gradient on the Drag Reduction Characteristics of Riblets"],"prefix":"10.3390","volume":"17","author":[{"given":"Qiyue","family":"Ma","sequence":"first","affiliation":[{"name":"School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peiqing","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2557-1972","authenticated-orcid":false,"given":"Hao","family":"Guo","sequence":"additional","affiliation":[{"name":"School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fei","family":"Cui","sequence":"additional","affiliation":[{"name":"School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yankun","family":"Su","sequence":"additional","affiliation":[{"name":"School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chunpeng","family":"Li","sequence":"additional","affiliation":[{"name":"School of Aeronautic Science and Engineering, Beihang University, Beijing 100191, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,11,20]]},"reference":[{"key":"ref_1","unstructured":"Risse, K., Stumpf, E., and Schr\u00f6der, W. (2016). Preliminary Overall Aircraft Design with Hybrid Laminar Flow Control, Shaker. Berichte aus der Luft- und Raumfahrttechnik."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Walsh, M. (1982, January 11\u201314). Turbulent Boundary Layer Drag Reduction Using Riblets. Proceedings of the 20th Aerospace Sciences Meeting, Orlando, FL, USA.","DOI":"10.2514\/6.1982-169"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"485","DOI":"10.2514\/3.60126","article-title":"Riblets as a Viscous Drag Reduction Technique","volume":"21","author":"Walsh","year":"1983","journal-title":"AIAA J."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Walsh, M., and Lindemann, A. (1984, January 9\u201312). Optimization and Application of Riblets for Turbulent Drag Reduction. Proceedings of the 22nd Aerospace Sciences Meeting, Reno, NV, USA.","DOI":"10.2514\/6.1984-347"},{"key":"ref_5","unstructured":"Walsh, M.J. (1990). Riblets. Viscous Drag Reduction in Boundary Layers, American Institute of Aeronautics and Astronautics."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"417","DOI":"10.1017\/S0022112089002892","article-title":"Near-Wall Structure of a Turbulent Boundary Layer with Riblets","volume":"208","author":"Choi","year":"1989","journal-title":"J. Fluid Mech."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Bacher, E., and Smith, C. (1985, January 12\u201314). A Combined Visualization-Anemometry Study of the Turbulent Drag Reducing Mechanisms of Triangular Micro-Groove Surface Modifications. Proceedings of the Shear Flow Control Conference, Boulder, CO, USA.","DOI":"10.2514\/6.1985-548"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1017\/S0022112098008921","article-title":"Secondary Flow Induced by Riblets","volume":"363","author":"Goldstein","year":"1998","journal-title":"J. Fluid Mech."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1017\/S0022112089002247","article-title":"The Viscous Flow on Surfaces with Longitudinal Ribs","volume":"206","author":"Bechert","year":"1989","journal-title":"J. Fluid Mech."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1017\/S0022112091002641","article-title":"Resistance of a Grooved Surface to Parallel Flow and Cross-Flow","volume":"228","author":"Luchini","year":"1991","journal-title":"J. Fluid Mech."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"100807","DOI":"10.1016\/j.paerosci.2022.100807","article-title":"Equilibrium and Non-Equilibrium Turbulent Boundary Layers","volume":"131","author":"Devenport","year":"2022","journal-title":"Prog. Aerosp. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1007\/BF00195591","article-title":"The Reduction of Skin Friction by Riblets under the Influence of an Adverse Pressure Gradient","volume":"15","author":"Nieuwstadt","year":"1993","journal-title":"Exp. Fluids"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"932","DOI":"10.2514\/3.13170","article-title":"Turbulent Boundary Layer in an Adverse Pressure Gradient\u2014Effectiveness of Riblets","volume":"34","author":"Debisschop","year":"1996","journal-title":"AIAA J."},{"key":"ref_14","unstructured":"Klumpp, S., Guldner, T., Meinke, M., and Schr\u00f6der, W. (July, January 28). Riblets in a Turbulent Adverse-Pressure Gradient Boundary Layer. Proceedings of the 5th Flow Control Conference, Chicago, IL, USA."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1016\/j.ijheatfluidflow.2015.07.022","article-title":"Riblet Drag Reduction in Mild Adverse Pressure Gradients: A Numerical Investigation","volume":"56","author":"Boomsma","year":"2015","journal-title":"Int. J. Heat Fluid Flow"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1007\/978-94-009-2159-7_7","article-title":"Effects of Longitudinal Pressure Gradients on Turbulent Drag Reduction with Riblets","volume":"Volume 4","author":"Coustols","year":"1990","journal-title":"Turbulence Control by Passive Means"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Kurita, M., Nishizawa, A., Kwak, D., Iijima, H., Iijima, Y., Takahashi, H., Sasamori, M., Abe, H., Koga, S., and Nakakita, K. (2018, January 25\u201329). Flight Test of a Paint-Riblet for Reducing Skin-Friction. Proceedings of the 2018 Applied Aerodynamics Conference, Atlanta, Georgia.","DOI":"10.2514\/6.2018-3005"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1007\/BF00404819","article-title":"Influence of Wall Riblets on Diffuser Flow","volume":"46","author":"Truong","year":"1989","journal-title":"Appl. Sci. Res."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"229","DOI":"10.1007\/BF00404820","article-title":"Drag Measurements on Planar Riblet Surfaces at High Subsonic Speeds","volume":"46","author":"Squire","year":"1989","journal-title":"Appl. Sci. Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"571","DOI":"10.1016\/S0376-0421(02)00048-9","article-title":"Aircraft Viscous Drag Reduction Using Riblets","volume":"38","author":"Viswanath","year":"2002","journal-title":"Prog. Aerosp. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Ma, Q.Y., Liu, P.q., Guo, H., Cui, F., Su, Y.K., Li, C.P., and Zhang, T.J. (2025). Experimental Investigation on Drag Reduction Characteristics of Riblets Considering the Flow Environment of Fuselage. Aerosp. Sci., 12.","DOI":"10.3390\/aerospace12110985"},{"key":"ref_22","unstructured":"White, F.M. (2005). Viscous Fluid Flow, McGraw-Hill. [3rd ed.]."},{"key":"ref_23","unstructured":"(2025, August 31). NASA Common Research Model|Providing Data Worldwide, Available online: https:\/\/commonresearchmodel.larc.nasa.gov\/."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"109975","DOI":"10.1016\/j.expthermflusci.2019.109975","article-title":"Experimental Realisation of Near-Equilibrium Adverse-Pressure-Gradient Turbulent Boundary Layers","volume":"112","author":"Vila","year":"2020","journal-title":"Exp. Therm. Fluid Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.ijheatfluidflow.2016.03.004","article-title":"Scaling and Statistics of Large-Defect Adverse Pressure Gradient Turbulent Boundary Layers","volume":"59","author":"Gungor","year":"2016","journal-title":"Int. J. Heat Fluid Flow"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"568","DOI":"10.1016\/j.ijheatfluidflow.2008.01.016","article-title":"Effects of an Adverse Pressure Gradient on a Turbulent Boundary Layer","volume":"29","author":"Lee","year":"2008","journal-title":"Int. J. Heat Fluid Flow"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"A35","DOI":"10.1017\/jfm.2023.160","article-title":"Comparison of Smooth- and Rough-Wall Non-Equilibrium Boundary Layers with Favourable and Adverse Pressure Gradients","volume":"959","author":"Volino","year":"2023","journal-title":"J. Fluid Mech."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1017\/S0022112096004673","article-title":"Experiments on Drag-Reducing Surfaces and Their Optimization with an Adjustable Geometry","volume":"338","author":"Bechert","year":"1997","journal-title":"J. Fluid Mech."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"503","DOI":"10.1017\/S0022112093002575","article-title":"Direct Numerical Simulation of Turbulent Flow over Riblets","volume":"255","author":"Choi","year":"1993","journal-title":"J. Fluid Mech."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"A37","DOI":"10.1017\/jfm.2021.2","article-title":"Influence of Riblet Shapes on the Occurrence of Kelvin\u2013Helmholtz Rollers","volume":"913","author":"Endrikat","year":"2021","journal-title":"J. Fluid Mech."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"A55","DOI":"10.1017\/jfm.2021.310","article-title":"Dispersive Stresses in Turbulent Flow over Riblets","volume":"917","author":"Modesti","year":"2021","journal-title":"J. Fluid Mech."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"109160","DOI":"10.1016\/j.ijheatfluidflow.2023.109160","article-title":"Effect of Straight Riblets of the Underlying Surface on Wall Bounded Flow Drag","volume":"102","author":"Chan","year":"2023","journal-title":"Int. J. Heat Fluid Flow"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"317","DOI":"10.1017\/jfm.2011.114","article-title":"Hydrodynamic Stability and Breakdown of the Viscous Regime over Riblets","volume":"678","year":"2011","journal-title":"J. Fluid Mech."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1007\/s003480000150","article-title":"Flow Field Analysis of a Turbulent Boundary Layer over a Riblet Surface","volume":"30","author":"Lee","year":"2001","journal-title":"Exp. Fluids"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1007\/s00348-022-03534-2","article-title":"Experimental Investigation on the Degradation of Turbulent Friction Drag Reduction over Semi-Circular Riblets","volume":"63","author":"Li","year":"2022","journal-title":"Exp. Fluids"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1017\/S0022112076003145","article-title":"On the Wall Structure of the Turbulent Boundary Layer","volume":"76","author":"Blackwelder","year":"1976","journal-title":"J. Fluid Mech."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1017\/S0022112082002225","article-title":"On the Structure of Turbulent Channel Flow","volume":"122","author":"Johansson","year":"1982","journal-title":"J. Fluid Mech."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"173","DOI":"10.1146\/annurev.fluid.36.050802.122103","article-title":"Turbulent Flows over Rough Walls","volume":"36","year":"2004","journal-title":"Annu. Rev. Fluid Mech."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"S243","DOI":"10.1063\/1.861737","article-title":"Large Structure in a Turbulent Boundary Layer","volume":"20","author":"Brown","year":"1977","journal-title":"Phys. Fluids"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1017\/jfm.2019.408","article-title":"Interaction of Coherent Flow Structures in Adverse Pressure Gradient Turbulent Boundary Layers","volume":"873","author":"Bross","year":"2019","journal-title":"J. Fluid Mech."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"114504","DOI":"10.1103\/PhysRevLett.99.114504","article-title":"Reynolds Number Invariance of the Structure Inclination Angle in Wall Turbulence","volume":"99","author":"Marusic","year":"2007","journal-title":"Phys. Rev. Lett."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1017\/S0022112007008518","article-title":"Turbulence Structure in Rough- and Smooth-Wall Boundary Layers","volume":"592","author":"Volino","year":"2007","journal-title":"J. Fluid Mech."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"309","DOI":"10.1017\/S0022112001005924","article-title":"Experimental Study of Wall Boundary Conditions for Large-Eddy Simulation","volume":"446","author":"Marusic","year":"2001","journal-title":"J. Fluid Mech."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"3504","DOI":"10.1063\/1.1399291","article-title":"Particle Image Velocimetry Measurements of Flow over a Wavy Wall","volume":"13","author":"Nakagawa","year":"2001","journal-title":"Phys. Fluids"},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1017\/S0022112009006946","article-title":"Large-Scale Amplitude Modulation of the Small-Scale Structures in Turbulent Boundary Layers","volume":"628","author":"Mathis","year":"2009","journal-title":"J. Fluid Mech."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"025117","DOI":"10.1063\/1.4866458","article-title":"High Spatial Range Velocity Measurements in a High Reynolds Number Turbulent Boundary Layer","volume":"26","author":"Gnanamanickam","year":"2014","journal-title":"Phys. Fluids"},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"17","DOI":"10.1017\/S0022112009006934","article-title":"Buffer Layer Structures Associated with Extreme Wall Stress Events in a Smooth Wall Turbulent Boundary Layer","volume":"633","author":"Sheng","year":"2009","journal-title":"J. Fluid Mech."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"041301","DOI":"10.1063\/1.2717527","article-title":"Hairpin Vortex Organization in Wall Turbulence","volume":"19","author":"Adrian","year":"2007","journal-title":"Phys. Fluids"}],"container-title":["Symmetry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-8994\/17\/11\/2007\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,11,22]],"date-time":"2025-11-22T05:17:10Z","timestamp":1763788630000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-8994\/17\/11\/2007"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,11,20]]},"references-count":48,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2025,11]]}},"alternative-id":["sym17112007"],"URL":"https:\/\/doi.org\/10.3390\/sym17112007","relation":{},"ISSN":["2073-8994"],"issn-type":[{"type":"electronic","value":"2073-8994"}],"subject":[],"published":{"date-parts":[[2025,11,20]]}}}