Abstract
Flow conditions in complex terrains such as fjords are highly three-dimensional and thus not properly captured by the wind flow models developed for homogenous terrains. In the present study, we explore the potential of computational fluid dynamics (CFD) simulations relying on the steady 3D Reynolds-averaged Navier-Stokes equations to complement in-situ measurements from a long-span bridge in a narrow fjord. The validation is done using velocity data recorded in 2017 and 2018 by nine sonic anemometers mounted above the deck of a fjord-crossing suspension bridge. The flow characteristics studied are the along-bridge profile of the mean wind velocity, mean wind direction and mean angle of attack. The simulated flow shows that the non-uniform distributions of the mean angles of attack and wind direction along the bridge span are likely due to side-valley flows, which under certain conditions, predominate over those coming from the main valley. The measurements suggest that wind conditions corresponding to the dominating side-valley flows are associated with a high turbulence intensity at the bridge deck position. The paper highlights the complementary role of CFD studies and in-situ measurements for the design of a wind-sensitive structure, which may not be available using traditional semi-empirical modelling of topography effects.
Highlights
In the initial design of long-span bridges, the natural wind is commonly modelled with a zero-mean angle of attack (AOA) and uniform mean wind speed in the horizontal plane
The second case examined corresponds to a south-westerly wind direction of 210 at the inlet (Fig. 12), for which the flow from the side valley is no longer dominating at the fjord inlet
The influence of the local topography on the mean wind conditions recorded at the inlet of a narrow fjord, called Lysefjord, has been investigated by combining 3D steady Reynolds-averaged Navier-Stokes simulation with in-situ measurements from 3D sonic anemometers
Summary
In the initial design of long-span bridges, the natural wind is commonly modelled with a zero-mean angle of attack (AOA) and uniform mean wind speed in the horizontal plane. For industrial and design applications, it is fundamental that the computational cost remains as low as possible This requirement can be fulfilled by focusing on the mean flow characteristics as a first indicator of the influence of the local terrain on the wind conditions. This topic was only shortly covered in the reviews by Murakami (1997) or Blocken (2014), reinforcing the idea that CFD microscale flow in complex terrain is an emerging issue in civil engineering This topic has been addressed since the 2000s in the field of wind energy (Dhunny et al, 2017; Rodrigues et al, 2016; Toja-Silva et al, 2018) and aviation safety (Eidsvik et al, 2004; Rasheed and Sørli, 2013), wind engineering applications have a different focus in terms of flow characteristics, requiring a different approach. In highly complex terrain, the ASTER 30-m may be substantially less accurate than the SRTM 30-m dataset (Kervyn et al, 2008), which was observed in the case of the Lysefjord
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of Wind Engineering and Industrial Aerodynamics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
