Simulating wind and rain around a stadium determines the best design for keeping spectators dry. Results can be used to improve the design of future stadiums as well as to diagnose and correct problems with existing stadiums

Blocken, B.J.E.

Harten, van, M.

van Hooff, T.

English

Pure OAI Repository

 Dry runCitation for published version (APA):Blocken, B. J. E., van Hooff, T., & Harten, van, M. (2012). Dry run. ANSYS Advantage, 6(2), 29-32.Document status and date:Published: 01/01/2012Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 04. Oct. 2023ANSYS.COM © 2012 ANSYS, INC. ANSYS ADVANTAGE        29By Bert Blocken, Professor; Twan van Hooff, Ph.D. Student; and Marjon van Harten, M.Sc. Student, Eindhoven University of Technology Eindhoven, The NetherlandsWhen developing a sporting venue, designers must consider a large number of factors. Two important overall consid-erations are spectator comfort/safety and how the stadium itself could affect the play of the sport — and each has many facets. Anyone who has attended a sport-ing event in the rain will understand the dampening effect that this factor can have on event enjoyment. In semi-open stadium design, two of the greatest challenges are limiting wind on the field to avoid affecting play and protecting spectators from wind-driven rain. Historically, stadium design-ers largely ignored these factors because they were unable to determine how their designs would perform until after the venue had been built. Simulation is changing that.A team from Eindhoven University of Technology has conducted 3-D stud-ies of stadium design using ANSYS Fluent computational fluid dynamics (CFD) software to demonstrate the important effects of the architecture on both wind flow and wind-driven rain. Simulation of 12 different stadium configurations showed the precise areas where wind-driven rain would penetrate the seats in each type of stadium as well as the speed and direction of wind on the playing field. These results can be used to improve the design of future stadiums as well as to diagnose and correct problems with existing stadiums — such as using spe-cial paint to protect seats that frequently get wet to reduce maintenance costs.STADIUM DESIGN AND SIMULATION CHALLENGESMany stadiums in Europe and elsewhere have an open design in which the roof covers only the stands. In most cases, the roof does not extend farther than the sep-aration between the stands and the field, so wind-driven rain can reach a large area of seating, resulting in spectator discomfort. To the best of the authors’ knowledge, the first simulation of wind-driven rain in a stadium was published in 2008 [1]. This 2-D study was not able to capture the important effects of roof and stadium geometry. Simulation predicted the area of the stands that became wet in seven generic stadium designs. The study showed that roof design can strongly influence which areas stay dry and which become wet.The new Eindhoven study went a step further by using 3-D CFD to capture 3-D flow patterns and provide a more realistic assessment of the effect of roof geometry CONSTRUCTIONS imulating wind and rain around a stadium determines the best design for keeping spectators dry.AFAS stadium in AlkmaarPHOTO: AZ NVResults can be used to improve the design of future stadiums as well as to diagnose and correct problems with existing stadiums.Dry Run30        ANSYS ADVANTAGE  Volume VI  |  Issue 2  |  2012 on the area wetted by wind-driven rain [2]. One of the biggest challenges was modeling geometry that combines a very large computational domain with the need to model certain areas to a fine level of detail. Another challenge was the need to accurately model the wide range of sizes of potential rain droplets.12 DESIGN ALTERNATIVES CONSIDEREDThe stadium configurations in this study are based on the AFAS stadium in Alkmaar, The Netherlands, which seats 17,000 people and is the home of the AZ Alkmaar football team. Its exterior dimensions are 176.8 meters long by 138 meters wide by 22.5 meters high; it has a down-ward-sloped roof with an inclination of 13 degrees. The research team selected this stadium because of its unusual roof, which the architects intuitively chose with the goal of improving shelter from wind-driven rain. The team looked at four different stand arrangements: stands only on long sides of stadium (A), stands on all four sides (B), stands on all four sides with each end of the stands closed off (C), and a closed rectangular stadium (D). Researchers evaluated each stand arrangement with three different roof designs: upward sloped (1), flat (2), and downward sloped (3), yielding 12 differ-ent design configurations: A-1, A-2, A-3, B-1 and so on. Configuration D-3 matches the actual AFAS stadium design.The difference between the largest- (1,100 meters) and smallest- (less than 0.1 meters) length scales in the domain created challenges in producing the com-putational grid. The Eindhoven team generated the master grid by creating a series of premeshed 2-D cross sections, then using a series of translation and rotation operations. The master grid con-tained hexahedral and prismatic cells. This approach provides full control of grid quality and resolution. Researchers used higher-resolution mesh at the deck of the stadium, while lower resolution was applied to outside the stadium. They increased the grid resolution in the vicinity of the roof for a more detailed prediction of wind flow. The team deleted designated meshed volumes from the master grid to produce the mesh for each of the 12 different stadium design variants.Four different stand configurations were evaluated with three different roof designs, for a total of 12 possibilities.Increased grid resolution in the vicinity of the roof provided a more detailed prediction of wind flow.A. B.C. D.2-D wind flow patterns one meter above ground for the four different stand configurationsCONSTRUCTIONANSYS.COM © 2012 ANSYS, INC. ANSYS ADVANTAGE        31WIND-FLOW PATTERNSResearchers calculated steady-state wind- flow patterns around the stadiums using the Reynolds-averaged Navier–Stokes (RANS) CFD technique with a realiz-able k-epsilon turbulence model. They based this choice on earlier extensive validation efforts of wind-driven rain on A.A.B.C.D.B.C. D.3-D wind flow for four different stadium stand configurationsRaindrop trajectories for 1 mm raindrops and the same wind speed for four stadium configurations. Each column shows a different injection position for raindrops.building facades and over various types of small-scale topography, including hills and valleys [3, 4, 5]. They determined the wind-flow patterns in the field at a height of one meter above ground level (chosen to determine the impact of wind condi-tions on the game) for each of the four stand arrangements described earlier with a flat roof. The results for configura-tion A-2 revealed two large counter-rotat-ing vortices between the stands. These vortices are mainly driven by the cor-ner stream shear layer originating at the corners of the upstream stand. Applying fluid flow modeling to configuration B-2 revealed results similar to A-2, except that the velocities in the upstream cor-ners of the stadium are higher. The sim-ulation results show that the stands in the short edges of the stadium have a relatively small influence on the flow because the side flow is not obstructed by these stands and can pass through the area between the stand and the roof. Closing off the sides of the stands in configuration C-2 eliminates the vortices and, instead, shows that streams from two different corners combine to gener-ate two high-velocity jets directed toward the center of the stadium. Configuration D-2 has two vortices, but they are smaller and have a lower velocity than configura-tions A-2 and B-2 — so the flow pattern inside the stadium is considerably more complex. Additional small vortices exist above the field and underneath the roof.WIND-DRIVEN RAIN PATTERNSResearchers determined raindrop trajec-tories by injecting raindrops of different sizes in the calculated wind-flow motion and solving their equations of motion. Raindrops with diameters of 0.5 mm, 1 mm, 2 mm and 5 mm were considered. The raindrops were injected from the top of the domain with the local wind speed as horizontal injection velocity and ter-minal velocity as vertical injection velocity. Raindrops of 0.5 mm diame-ter represent the median diameter for drizzle (rainfall intensity of 0.1 mm/h), 1 mm diameter represents the median diameter for a rainfall intensity of 1 mm/h (common Dutch rain), 2 mm diameter represents 10 mm/h (heavy shower), and 5 mm diameter is the larg-est raindrop in heavy rain showers. The areas of the stadium receiving rain were calculated based on the calculated rain-drop trajectories for each stadium con-figuration. For configurations A and B, the large vortices between the upstream and downstream stand cause part of the upstream stand to be wetted, especially for smaller raindrop diameters that are more sensitive to the wind-flow pattern and can be more easily swept under-neath the roof. On the other hand, with configuration C, the wetting of the two 32        ANSYS ADVANTAGE  Volume VI  |  Issue 2  |  2012 CFD can provide detailed insight into wind-flow patterns and wind-driven rain distribution in a wide range of stadium configurations.Overview of wetted stand areas for stand arrangements C and D with three different roof typesOverview of wetted stand areas for stand arrangements A and B with three different roof typesstands is limited, especially for the downward-sloping roof. The closed ends of the stands effectively shield the stands from rain, especially for upward-sloping and flat roofs. Configuration D provides only limited wetting at the rows of the stands closest to the field.Wind flow and wind-driven rain affect spectator comfort and fair compe-tition, but until recently stadium design-ers have had no way to determine the performance of design alternatives based on these conditions. This study demon-strates that CFD can provide detailed insight into wind-flow patterns and wind-driven rain distribution in a wide range of stadium configurations. Much further work remains to be done, such as apply-ing design optimization to determine the ideal roof angle to maximize the comfort level of the spectators. References[1] Persoon, J.; van Hooff, T.; Blocken, B.; Carmeliet, J.; de Wit, M.H. On the Impact of Roof Geometry on Rain Shelter in Football Stadia. Journal of Wind Engineering and Industrial Aerodynamics. 2008, Vol. 96, Issue 8–9, pp. 1274–93.[2] van Hooff, T.; Blocken, B.; van Harten, M. 3D CFD Simulations of Wind Flow and Wind-Driven Rain Shelter in Sports Stadia: Influence of Stadium Geometry. Building and Environment. 2011, Vol. 46, Issue 1, pp. 22–37[3] Blocken, B.; Carmeliet, J. Validation of CFD Simulations of Wind-Driven Rain on a Low-Rise Building. Building and Environment. 2007, Vol. 42, Issue 7, pp. 2530–2548.[4] Blocken, B.; Poesen, J.; Carmeliet, J. Impact of Wind on the Spatial Distribution of Rain over Micro-Scale Topography — Numerical Modelling and Experimental Verification. Hydrological Processes. 2006, Vol. 20, Issue 2, pp. 345–368.[5] Blocken, B.; Carmeliet, J.; Poesen, J. Numerical Simulation of the Wind-Driven Rainfall Distribution over Small-Scale Topography in Space and Time. Journal of Hydrology. 2005, Vol. 315, Issues 1–4, pp. 252–273.CONSTRUCTION

Dry run

 Dry runCitation for published version (APA):Blocken, B. J. E., van Hooff, T., & Harten, van, M. (2012). Dry run. ANSYS Advantage, 6(2), 29-32.Document status and date:Published: 01/01/2012Document Version:Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the version of the article upon submission and before peer-review. There can beimportant differences between the submitted version and the official published version of record. Peopleinterested in the research are advised to contact the author for the final version of the publication, or visit theDOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and pagenumbers.Link to publicationGeneral rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright ownersand it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.            • Users may download and print one copy of any publication from the public portal for the purpose of private study or research.            • You may not further distribute the material or use it for any profit-making activity or commercial gain            • You may freely distribute the URL identifying the publication in the public portal.If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, pleasefollow below link for the End User Agreement:www.tue.nl/taverneTake down policyIf you believe that this document breaches copyright please contact us at:openaccess@tue.nlproviding details and we will investigate your claim.Download date: 05. Oct. 2023ANSYS.COM © 2012 ANSYS, INC. ANSYS ADVANTAGE        29By Bert Blocken, Professor; Twan van Hooff, Ph.D. Student; and Marjon van Harten, M.Sc. Student, Eindhoven University of Technology Eindhoven, The NetherlandsWhen developing a sporting venue, designers must consider a large number of factors. Two important overall consid-erations are spectator comfort/safety and how the stadium itself could affect the play of the sport — and each has many facets. Anyone who has attended a sport-ing event in the rain will understand the dampening effect that this factor can have on event enjoyment. In semi-open stadium design, two of the greatest challenges are limiting wind on the field to avoid affecting play and protecting spectators from wind-driven rain. Historically, stadium design-ers largely ignored these factors because they were unable to determine how their designs would perform until after the venue had been built. Simulation is changing that.A team from Eindhoven University of Technology has conducted 3-D stud-ies of stadium design using ANSYS Fluent computational fluid dynamics (CFD) software to demonstrate the important effects of the architecture on both wind flow and wind-driven rain. Simulation of 12 different stadium configurations showed the precise areas where wind-driven rain would penetrate the seats in each type of stadium as well as the speed and direction of wind on the playing field. These results can be used to improve the design of future stadiums as well as to diagnose and correct problems with existing stadiums — such as using spe-cial paint to protect seats that frequently get wet to reduce maintenance costs.STADIUM DESIGN AND SIMULATION CHALLENGESMany stadiums in Europe and elsewhere have an open design in which the roof covers only the stands. In most cases, the roof does not extend farther than the sep-aration between the stands and the field, so wind-driven rain can reach a large area of seating, resulting in spectator discomfort. To the best of the authors’ knowledge, the first simulation of wind-driven rain in a stadium was published in 2008 [1]. This 2-D study was not able to capture the important effects of roof and stadium geometry. Simulation predicted the area of the stands that became wet in seven generic stadium designs. The study showed that roof design can strongly influence which areas stay dry and which become wet.The new Eindhoven study went a step further by using 3-D CFD to capture 3-D flow patterns and provide a more realistic assessment of the effect of roof geometry CONSTRUCTIONS imulating wind and rain around a stadium determines the best design for keeping spectators dry.AFAS stadium in AlkmaarPHOTO: AZ NVResults can be used to improve the design of future stadiums as well as to diagnose and correct problems with existing stadiums.Dry Run30        ANSYS ADVANTAGE  Volume VI  |  Issue 2  |  2012 on the area wetted by wind-driven rain [2]. One of the biggest challenges was modeling geometry that combines a very large computational domain with the need to model certain areas to a fine level of detail. Another challenge was the need to accurately model the wide range of sizes of potential rain droplets.12 DESIGN ALTERNATIVES CONSIDEREDThe stadium configurations in this study are based on the AFAS stadium in Alkmaar, The Netherlands, which seats 17,000 people and is the home of the AZ Alkmaar football team. Its exterior dimensions are 176.8 meters long by 138 meters wide by 22.5 meters high; it has a down-ward-sloped roof with an inclination of 13 degrees. The research team selected this stadium because of its unusual roof, which the architects intuitively chose with the goal of improving shelter from wind-driven rain. The team looked at four different stand arrangements: stands only on long sides of stadium (A), stands on all four sides (B), stands on all four sides with each end of the stands closed off (C), and a closed rectangular stadium (D). Researchers evaluated each stand arrangement with three different roof designs: upward sloped (1), flat (2), and downward sloped (3), yielding 12 differ-ent design configurations: A-1, A-2, A-3, B-1 and so on. Configuration D-3 matches the actual AFAS stadium design.The difference between the largest- (1,100 meters) and smallest- (less than 0.1 meters) length scales in the domain created challenges in producing the com-putational grid. The Eindhoven team generated the master grid by creating a series of premeshed 2-D cross sections, then using a series of translation and rotation operations. The master grid con-tained hexahedral and prismatic cells. This approach provides full control of grid quality and resolution. Researchers used higher-resolution mesh at the deck of the stadium, while lower resolution was applied to outside the stadium. They increased the grid resolution in the vicinity of the roof for a more detailed prediction of wind flow. The team deleted designated meshed volumes from the master grid to produce the mesh for each of the 12 different stadium design variants.Four different stand configurations were evaluated with three different roof designs, for a total of 12 possibilities.Increased grid resolution in the vicinity of the roof provided a more detailed prediction of wind flow.A. B.C. D.2-D wind flow patterns one meter above ground for the four different stand configurationsCONSTRUCTIONANSYS.COM © 2012 ANSYS, INC. ANSYS ADVANTAGE        31WIND-FLOW PATTERNSResearchers calculated steady-state wind- flow patterns around the stadiums using the Reynolds-averaged Navier–Stokes (RANS) CFD technique with a realiz-able k-epsilon turbulence model. They based this choice on earlier extensive validation efforts of wind-driven rain on A.A.B.C.D.B.C. D.3-D wind flow for four different stadium stand configurationsRaindrop trajectories for 1 mm raindrops and the same wind speed for four stadium configurations. Each column shows a different injection position for raindrops.building facades and over various types of small-scale topography, including hills and valleys [3, 4, 5]. They determined the wind-flow patterns in the field at a height of one meter above ground level (chosen to determine the impact of wind condi-tions on the game) for each of the four stand arrangements described earlier with a flat roof. The results for configura-tion A-2 revealed two large counter-rotat-ing vortices between the stands. These vortices are mainly driven by the cor-ner stream shear layer originating at the corners of the upstream stand. Applying fluid flow modeling to configuration B-2 revealed results similar to A-2, except that the velocities in the upstream cor-ners of the stadium are higher. The sim-ulation results show that the stands in the short edges of the stadium have a relatively small influence on the flow because the side flow is not obstructed by these stands and can pass through the area between the stand and the roof. Closing off the sides of the stands in configuration C-2 eliminates the vortices and, instead, shows that streams from two different corners combine to gener-ate two high-velocity jets directed toward the center of the stadium. Configuration D-2 has two vortices, but they are smaller and have a lower velocity than configura-tions A-2 and B-2 — so the flow pattern inside the stadium is considerably more complex. Additional small vortices exist above the field and underneath the roof.WIND-DRIVEN RAIN PATTERNSResearchers determined raindrop trajec-tories by injecting raindrops of different sizes in the calculated wind-flow motion and solving their equations of motion. Raindrops with diameters of 0.5 mm, 1 mm, 2 mm and 5 mm were considered. The raindrops were injected from the top of the domain with the local wind speed as horizontal injection velocity and ter-minal velocity as vertical injection velocity. Raindrops of 0.5 mm diame-ter represent the median diameter for drizzle (rainfall intensity of 0.1 mm/h), 1 mm diameter represents the median diameter for a rainfall intensity of 1 mm/h (common Dutch rain), 2 mm diameter represents 10 mm/h (heavy shower), and 5 mm diameter is the larg-est raindrop in heavy rain showers. The areas of the stadium receiving rain were calculated based on the calculated rain-drop trajectories for each stadium con-figuration. For configurations A and B, the large vortices between the upstream and downstream stand cause part of the upstream stand to be wetted, especially for smaller raindrop diameters that are more sensitive to the wind-flow pattern and can be more easily swept under-neath the roof. On the other hand, with configuration C, the wetting of the two 32        ANSYS ADVANTAGE  Volume VI  |  Issue 2  |  2012 CFD can provide detailed insight into wind-flow patterns and wind-driven rain distribution in a wide range of stadium configurations.Overview of wetted stand areas for stand arrangements C and D with three different roof typesOverview of wetted stand areas for stand arrangements A and B with three different roof typesstands is limited, especially for the downward-sloping roof. The closed ends of the stands effectively shield the stands from rain, especially for upward-sloping and flat roofs. Configuration D provides only limited wetting at the rows of the stands closest to the field.Wind flow and wind-driven rain affect spectator comfort and fair compe-tition, but until recently stadium design-ers have had no way to determine the performance of design alternatives based on these conditions. This study demon-strates that CFD can provide detailed insight into wind-flow patterns and wind-driven rain distribution in a wide range of stadium configurations. Much further work remains to be done, such as apply-ing design optimization to determine the ideal roof angle to maximize the comfort level of the spectators. References[1] Persoon, J.; van Hooff, T.; Blocken, B.; Carmeliet, J.; de Wit, M.H. On the Impact of Roof Geometry on Rain Shelter in Football Stadia. Journal of Wind Engineering and Industrial Aerodynamics. 2008, Vol. 96, Issue 8–9, pp. 1274–93.[2] van Hooff, T.; Blocken, B.; van Harten, M. 3D CFD Simulations of Wind Flow and Wind-Driven Rain Shelter in Sports Stadia: Influence of Stadium Geometry. Building and Environment. 2011, Vol. 46, Issue 1, pp. 22–37[3] Blocken, B.; Carmeliet, J. Validation of CFD Simulations of Wind-Driven Rain on a Low-Rise Building. Building and Environment. 2007, Vol. 42, Issue 7, pp. 2530–2548.[4] Blocken, B.; Poesen, J.; Carmeliet, J. Impact of Wind on the Spatial Distribution of Rain over Micro-Scale Topography — Numerical Modelling and Experimental Verification. Hydrological Processes. 2006, Vol. 20, Issue 2, pp. 345–368.[5] Blocken, B.; Carmeliet, J.; Poesen, J. Numerical Simulation of the Wind-Driven Rainfall Distribution over Small-Scale Topography in Space and Time. Journal of Hydrology. 2005, Vol. 315, Issues 1–4, pp. 252–273.CONSTRUCTION

Blocken, BJE Bert

Hooff, TAJ Twan  van

Harten, M Marjon  van

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