Wind Loads on High Building
The following study compares the wind pressure on a high building obtained by RWIND Simulation with the results published by Dagnew et al. at the 11th Americas Conference on Wind Engineering in June, 2009. In this paper, the Commonwealth Advisory Aeronautical Council (CAARC) building is used as a model, and the results of several different numerical methods are compared with experimental data obtained from wind tunnels.
The RWIND Simulation program is primarily designed to quickly calculate results even for relatively complex and large models. Default settings were used for a quick calculation, which subsequently took only 5 minutes on a standard PC. The results obtained are in relatively close agreement with those published in the above article , and are discussed in more detail below.
Computational Domain and Mesh
The CAARC building is a rectangular prismatic shape with dimensions of 150 ft by 100 ft by 600 ft in height. The wind tunnel dimensions are 4,950 ft in the streamwise direction, 3,000 ft in the spanwise direction, and the total height is equal to 1,200 ft.
The finite volume mesh was locally refined near the building model with the total number of mesh cells at 540,180. Although RWIND Simulation allows calculations on significantly finer meshes (up to 50 million cells), a relatively coarse mesh was selected for a quick calculation.
The simulation parameters and the inlet wind velocity profile are defined according to Dagnew et al. , and are displayed in Image 02.
The model boundary conditions are described in Table 1.
|Parameters||Top, Left, and Right Faces||Inlet||Outlet||Building Walls and Ground|
|Velocity||Slippage||Velocity profile||Zero gradient||0 m/s|
|Compression||Zero gradient||0 Pa||Zero gradient||Zero gradient|
The k‑epsilon turbulence model was used, and the inlet turbulent intensity was set to 0.15%.
The calculation was performed with the RWIND Simulation Solver, which is relative to the OpenFOAM-SIMPLE family of solvers. It is a steady-state solver for incompressible, turbulent flow. The entire simulation, including mesh generation and result preparation, was completed in 5 minutes on a PC with 8 cores (Intel i9‑9900K). The residual pressure convergence criterion was set to 0.001, which is the standard value for the quickest calculation, and was achieved after 350 iterations. The minimum residual pressure is 0.0001, and it could be reached after 700 iterations while continuing the calculation. However, the results were not significantly affected.
Image 05 through Image 07 show the pressure distribution on the building surface and the velocity field. For validation and comparison purposes, the calculated pressure coefficient cp is compared to the data obtained from  in Image 9 through Image 11. The cp coefficient is calculated as follows:
|p||Static pressure at the point which the pressure coefficient is being evaluated|
|p∞||Static pressure in the freestream (here: p∞ = 0 Pa)|
|ρ||Air density (here ρ = 1.2 kg/m³)|
|vH||Freestream velocity at the building height (here: vH = 12.7 m/s)|
The RWIND Simulation results and experimental results according to Dagnew et al.  on the windward face are in close comparison. On the sidewall and leeward faces, 10% - 20% differences between the measured and the calculated data are observed, which can be explained by the turbulence model (k-epsilon) used and the coarse computational mesh. The result accuracy can be improved by using more accurate turbulence models (LES), which will be available in future versions of RWIND Simulation.
RWIND Simulation Results:
Comparison with the data and results published in :
Dipl.-Ing. (BA) Andreas Niemeier, M.Eng.
Mr. Niemeier is responsible for the development of RFEM, RSTAB, and the add-on modules for tensile membrane structures. Also, he is responsible for quality assurance and customer support.
- Software for Wind Simulation & Wind Load Generation on Structures
- Product Description of RWIND Simulation
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Since wind on laterally open structures is not addressed in the Eurocode, the 4 cases of the German DIN 1055 Part 4 are referenced.
Values of Mean Pressure Coefficients cp Along Perimeter at Z/H = 2/3. Comparison with Results of Other Numerical Methods Published in 
Determination, implementation, and displaying wind flow around structures/objects using digital wind tunnel.
RFEM and RSTAB have a special interface for exporting models (i.e. structures defined by members and surfaces) to RWIND Basic. In this interface, the wind directions to be analyzed are defined by means of related angular positions about the vertical model axis, and the height-dependent wind and turbulence intensity profile is defined on the basis of a wind standard. Based on this information, you can use stored calculation parameters for a stationary calculation for each angular position.
You can also run the RWIND Basic program manually without the interface in RFEM and RSTAB. In this case, the structures and terrain environment in RWIND Basic are directly modeled by importing VTP, STL, OBJ, and IFC files. The height-dependent wind load and other fluid-mechanical data can be defined directly in RWIND Basic.
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