Noack, M.

Puckert, D. K.

Wieprecht, S.

English

Hydraulic Engineering Repository

Article, Published VersionPuckert, D. K.; Noack, M.; Wieprecht, S.Neckarwelle: A river surfing wave facility in the heart of thecity of StuttgartHydrolinkVerfügbar unter/Available at: https://hdl.handle.net/20.500.11970/109409Vorgeschlagene Zitierweise/Suggested citation:Puckert, D. K.; Noack, M.; Wieprecht, S. (2018): Neckarwelle: A river surfing wave facility inthe heart of the city of Stuttgart. In: Hydrolink 2018/2. Madrid: International Association forHydro-Environment Engineering and Research (IAHR). S. 38-40. https://iahr.oss-accelerate.aliyuncs.com/library/HydroLink/HydroLink2018_02_Leisure_Hydraulics.pdf.Standardnutzungsbedingungen/Terms of Use:Die Dokumente in HENRY stehen unter der Creative Commons Lizenz CC BY 4.0, sofern keine abweichendenNutzungsbedingungen getroffen wurden. Damit ist sowohl die kommerzielle Nutzung als auch das Teilen, dieWeiterbearbeitung und Speicherung erlaubt. Das Verwenden und das Bearbeiten stehen unter der Bedingung derNamensnennung. Im Einzelfall kann eine restriktivere Lizenz gelten; dann gelten abweichend von den obigenNutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte.Documents in HENRY are made available under the Creative Commons License CC BY 4.0, if no other license isapplicable. Under CC BY 4.0 commercial use and sharing, remixing, transforming, and building upon the materialof the work is permitted. In some cases a different, more restrictive license may apply; if applicable the terms ofthe restrictive license will be binding.38 hydrolink number 2/2018Why river surfing?Today, the pleasure of riding waves and the thrillof feeling the powers of nature has made surfingone of the most popular and fastest growingsports. Meanwhile, there are millions of ‘land-locked’ surfers in continental regions, relying onflights, or long trips to coastal areas. At thesame time, the best spots become increasinglycrowded and visitors often struggle to competeagainst highly skilled local surfers. The lack ofsurfing opportunities has initiated artificial ‘wave’projects in water parks [1], indoor leisure sites[2], wave pools [3] or even barreling wavemachines of the size of a football stadium [4]. Amore economic and environmentally friendlyapproach is to use the natural power of rivers tocreate a stationary wave. A well-known exampleis the Eisbach River in Munich, Germany, whichattracts thousands of tourists every year. In Stuttgart, Germany, a group of surfers andscientists are investigating the opportunity ofinstalling a surfable wave in the Neckar River.The prospective Neckarwelle (‘Neckar wave’)will be situated in the vibrant area ofUntertürkheim in Stuttgart. The scenery aroundthe proposed wave area is beautiful and thewave would fit naturally to this spot, whereswimming, rowing and kayaking is alreadyoffered [Figure 1]. A map of the location isshown in Figure 2. The wave is not in the mainchannel of the Neckar River itself but in adiverted side channel, which carries the majorityof the flow. A hydraulic power plant is locatedupstream of the wave and represents animportant aspect of the design of the wavefacility. This side channel is advantageous as itis not used for navigation and it offers protectionfor the wave facility from extreme flows andNECKARWELLE: A RIVER SURFINGWAVE FACILITY IN THE HEART OFTHE CITY OF STUTTGART BY D. K. PUCKERT, B. MESTER, M. NOACK & S. WIEPRECHTExperiencing the joy and excitement of riding perfect waves is the dream of many surfers living far from the sea.In Stuttgart, this dream could soon become reality with the installation of a stationary wave in the River Neckar. Tofind the optimal hydraulic conditions, the flow of the river is replicated both experimentally and through numericalsimulations. The results of these investigations will be key elements in the design of the perfect river wave.Figure 1. Rendering of prospective Neckarwelle39hydrolink number 2/2018kinetic energy at the location of the wave. Thevelocity at the wave trough is in the order of 3.5m/s, yielding Froude numbers in a range of 1.5to 3. A hydraulic jump forms closelydownstream of the wave, where the supercriticalflow conditions are transformed into subcriticalflow conditions. A result of the pressure increasedue to the hydraulic jump is the formation of arecirculation zone with a rotating vortex belowthe layer of supercritical flow. This recirculationzone has a significant impact on the formationof the wave and on the safety of the surfer [5].At constant inflow conditions, this phenomenonis stationary and the result is a standing wave[6]. However, only the maximum wave, aspecific type of hydraulic jump, can be surfed.The maximum wave features a smooth surfaceand leads to both the greatest wave height andmajor inclination [7]. The maximum wave onlyforms under specific conditions and is highlysensitive to any variations in these conditions.For instance, a 5 % reduction of the tailwaterheight reduces the total wave height by 50 %[5]. Previous studies investigated the physicalmechanisms for the wave formation process[6,5,8]. However, given the restricting simplifica-tions made in the different experimental set-ups,the results of these studies are not transferableto the Neckar River. Physical ExperimentsA scaled model of the planned design wasconstructed in a laboratory flume at theHydraulic Laboratory of the Institute forModelling Hydraulic and EnvironmentalSystems, University of Stuttgart, Germany. A novel aspect of this work is the combination of all relevant hydraulic and geometrical floating debris. The difference between theheadwater and tailwater level at the power plantis 3.6 m with approximately 1 m of head beingrequired to operate the wave. The science behind river wavesIn ocean surfing, the surfer moves along with apropagating shallow water wave until it breaks.In contrast to this, river waves are created by ahydraulic jump. The working principle issketched in Figure 3. To carry the weight of therider, the surfboard requires a sufficiently highflow velocity and a certain gradient of the watersurface. The required velocity is achieved byimpounding the water level upstream of thewave and then guiding the flow in thestreamwise direction down a ramp with a shortdeflector at its end. Physically speaking,potential energy is accumulated by increasingthe level of headwater and then converted intoIAHRDominik K. Puckert graduated inAerospace Engineering andcurrently works as a Ph.D. studentat the Institute of Aerodynamicsand Gas Dynamics, University ofStuttgart. His research subject ison experimental boundary layerinstabilities and his passion forsurfing made him member of the management board ofNeckarwelle e.V.Benedikt Mester, as part of hismaster thesis, conducts thephysical ‘Neckarwelle’experiments at the University ofStuttgart. His research interestfocuses on PIV, CFD andhydromorphological processes.Markus Noack is the head of theHydraulic Laboratory at theInstitute for Modelling Hydraulicand Environmental System,University of Stuttgart. He joinedthe IAHR committee forExperimental Methods andInstrumentation in 2017 and hisresearch is focused on experimental investigation ofhydraulic and sedimentary processes.Silke Wieprecht is Professor andhead of the department HydraulicEngineering and Water ResourcesManagement at the Institute forModelling Hydraulic andEnvironmental System, Universityof Stuttgart. Currently, she is VicePresident (Europe) of IAHR andresponsible for Innovation and Professional Development(IPD) activities within the association. Her research interests lie in exploring EnvironmentalSystems, Hydromorphology as well as Monitoring,Measuring and Modelling.Figure 3. Schematic sketch of working principle and experimental set-upFigure 2. Map of Neckarwelle location40 hydrolink number 2/2018parameters in one physical experiment. Theupstream boundary conditions are determinedby the power plant operation as well as by thenatural fluctuations of the flow rate whereas thedownstream boundary conditions are deter-mined by the water level of the Neckar River.Investigations into the influence of the differentparameters will lead to a deeper understandingof the wave formation mechanisms, which isvital to adapt the prospective wave to naturallyfluctuating boundary conditions. The experimental setup comprises a height-adjustable ramp to impound water in order togain potential energy and to accelerate the flowtowards the wave. At the end of the ramp, adeflector is attached for the fine-tuning of thewave s face. Both the deflector and the rampare variable in length and angle to examinewhether the step height beneath the deflector orthe inclination of the ramp is more important forthe wave formation. In addition, other aspects ofthe design, such as the influence of the ramp’slength, have not been addressed in the literatureto the authors’ knowledge.  It is noted thatdifferent studies on surfing facilities do not showgood agreement on whether a deflector onlybalances the tailwater fluctuations, or if it canactually increase the wave height [5, 8]. Numerical simulations The experimental work is supported bynumerical simulations performed at the Instituteof Aerodynamics and Gas Dynamics at theUniversity of Stuttgart. The open-source codeOpenFOAM is used to simulate the wave usingthe finite volume method. Two approaches areused to simulate the interfaces of air and water,namely the volume-of-fluids method and theisoAdvector method. The simulations are firstverified with a simple geometry against theexperimental data and will then be extended tomore complex geometries at a later stage of theproject.Future workThe results of the experimental and numericalstudies will provide information for theconceptual design of a hydraulic structure thatproduces surfing waves for the varyingboundary conditions at the Neckar River. Manyadditional investigations of non-technicalaspects of the planned Neckarwelle arecurrently ongoing such as looking at waterquality, ecological aspects, safety, legal issuesand financing. This work is performed in closecooperation with the City of Stuttgart, NeckarRiver authorities, the hydropower company andresidents. The social impact of the surfing wavefacility on Stuttgart will be immense. The goal ofthe team of surfers and scientists working onthis project is to bring together all groups ofdifferent ages and social backgrounds inter-ested in this exciting sport.AcknowledgementsWe thank G. Axtmann, M. Giebel, H. P.Koschitzky, K. Mouris, U. Rist, G. Schmid, P.Sommer and Y. Wu for their support in the scien-tific part of this project. The dedicated work ofM. Bauer, S. Böhrs, J. Bubeck, M. and S.Mannschreck and V. Sellmeier for theNeckarwelle e.V. is acknowledged. nReferences[1] McLaughlin Whitewater Design Group. https://mclaughlinwhite-water.com/contact, accessed: April 10, 2018.[2] Jochen Schweizer Arena. Erlebniswelt MünchenBetriebsgesellschaft mbH. https://www.jochen-schweizer-arena.de, accessed: April 10, 2018.[3] Wasserski Langenfeld GmbH. https://www.surf-langenfeld.deaccessed: April 10, 2018.[4] Kelly Slater Wave Company. http://www.kswaveco.com, accessed:April 10, 2018.[5] Koch, Christof. “Einfluss einer Klappe auf die Surfbarkeit stehenderWellen”. Master Thesis at ETH Zürich. 2016.[6] Trachsel, Jürg. “Surfbare Wellen.” Project Report at ETH Zürich.2013. [7] Ohtsu, Iwao & Yasuda, Youichi. “Transition from supercritical tosubcritical flow at an abrupt drop.” Journal of Hydraulic Research,VOL 29:3, pp. 309-328. 1991.[8] von Wyl, Rafael. “Einfluss einer Klappe auf die Surfbarkeitstehender Wellen.” Master Thesis at ETH Zürich. 2015. Professor Pavel (Paul) Novak passed away on the 24th of February2018 at the age of 99. He was born on the 7th of September 1918in Stribro, now located in the Czech Republic. He lost family to theHolocaust and first came to England during WW2, studyingengineering at the University of London, and making a contributionto the war effort by interrogating German POWs and as a memberof the Home Guard. He met his future wife Elizabeth (Eli) in 1943while staying in Nottingham. After the war he returned toCzechoslovakia, was from 1950 to 1955 Deputy Director of theWater Research Institute in Prague and later Director of the Instituteof Hydrodynamics, the Czechoslovak Academy of Sciences. In1968, when the Soviet army invaded Czechoslovakia, he returnedto Britain where he was offered a position at Newcastle University.Prof. Novak was an internationally leading hydraulic engineer, and wrote severalnoteworthy books on the subject. He was Professor of Civil and HydraulicEngineering in the Department of Civil Engineering from 1970-1983 and was Headof Department 1981-83. Pavel retired then and was accorded the title of EmeritusProfessor. By then, the Water Resources Group was the largest suchpostgraduate group in the UK. His contribution to Newcastle was immense andhe continued until recent times as an author and mentor. He held the Universityand city in his greatest affection as a place where he found freedom from the diffi-culties in central Europe in his earlier life. This affection is reciprocated.Prof. Novak was the first official Editor of the Journal of Hydraulic Research (JHR)from 1983, following Johannes T. Thijsse (1893-1984), who had done this job asIAHR Executive Director from JHR foundation in 1963. Pavel has taken thisposition for 8 years until 1991, from when JHR Editors serve for 5years. Pavel must be credited for having made JHR an interna-tionally accepted journal, one of the few then published in Europe.In parallel, Pavel was a successful book author. Of note is his bookModels in hydraulic engineering (1981) written jointly with JaroslavCabelka (1906-1989), his Hydraulic Structures (2001) and hisHydraulic Modelling (2010). In addition, he was the editor of thebook series Developments in Hydraulic Engineering. He alsoauthored more than 100 journal and congress papers. PavelNovak was an Honorary IAHR Member and awarded the ASCEHydraulic Structures Medal, among others. He was awarded in2008 the highest honorary medal ‘De Scientia et Humanitateoptime Meritis’ of the Academy of Sciences of the Czech Republic.In his retirement, Paul painted landscapes with great enthusiasm and continuedto write text books. He travelled widely and enjoyed many years of activity, onlygiving up skiing in his 70s.Following the death of Eli after 70 years of marriage, he spent his last years inThe Philip Cussins House in Gosforth he communicating from there with family,friends and colleagues often via email. Those, who were present at the 2017 ICESeniors Annual Lunch will recall how he spoke, still with clarity and strength.Pavel is survived by his son Michal, daughter Zuzana, and over 50 grandchildrenand great grandchildren. He will be greatly missed by all who knew him.Eric Valentine and Willi H. HagerPavel Novak (1918-2018)

Neckarwelle: A river surfing wave facility in the heart of the city of Stuttgart

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Neckarwelle: A river surfing wave facility in the heart of the city of Stuttgart

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