In addition to our technical support (e.g. via chat), you’ll find resources on our website that may help you with your design using Dlubal Software.
Frequently Asked Questions (FAQ)
Customer Support 24/7
RWIND Simulation is exclusively compatible with RFEM due to CFD modeling which requires a finite element calculation. The model created in RSTAB can be opened in RFEM. The wind load parameters can be defined in the RFEM dialog Simulate and Generate Wind Loads.
At the bottom of the Wind load tab, it is possible to stay and automatically generate the loads for the corresponding load cases after the CFD calculation has been run in the background.
If you would rather perform the wind simulation in RWIND, click the button Open in in the Load cases tab of RWIND Simulation.
To obtain the trial version of RWIND Simulation, proceed as indicated in this FAQ .
A user-defined wind load distribution is not provided in the Eurocode. In order to implement a user-defined wind load distribution in the RF‑/TOWER Loading add-on module, this can only be done after conversion to DIN, for example, DIN 4131:1993‑11, see Figure 01, Window "1.3 Wind Load - Part 1."
Then, you can select the user-defined distribution in Window 1.4 "Wind Load - Part 2," and define it in the adjacent table, see Figure 02.
AnswerThe 'Simulate and Generate Wind Loads' function for exporting models to RWIND Simulation is available in RFEM or RSTAB from version x.21.01 of 22.10.2019.With a valid service contract you can download the current program version from your Dlubal account. It is enough to log in here:If you do not have a service contract, you can download the program version you have purchased on the following page:
AnswerThe internal pressure coefficients do not need to be considered with in the RWIND Simulation program.RWIND Simulation always outputs the net pressure on the surfaces in RFEM. When it comes to a simulation with a building that has open windows in RWIND Simulation, there is an internal pressure acting on the inside of the building. The program uses this information to determine the resulting pressure based on the external and internal surfaces. This can be seen in Figure 1.A comparison cannot be made between this coefficient in the standard and a CFD calculation because there is no direct correlation.
For the calculation, the program creates a solid mesh between the model and the outer sides of the wind tunnel. In this case, the solid mesh does not connect directly to the model geometry, but to a separate model wrapping mesh situated around the model geometry. This model wrapping mesh has a certain distance to the exact model geometry, depending on the model mesh setting (Simplified Model - Shrink-Wrapping-Mesh). Similar to the surrounding model wrapping mesh, the exact model geometry itself is also represented from a wrapping mesh, but on the exact model shape.
Figure 01 - Mesh Types
With the OpenFOAM calculation, a print result is obtained on each solid element. These values are extrapolated to the respective edge nodes at the transition to the model. To determine the final surface pressures on the model geometry, the pressures at the edge nodes of the solid mesh are transformed into the exact model wrapping mesh in a further step. In case the triangular meshing of the exact model mesh geometry is too rough, the last transformation process initiates a partial refinement of the exact model wrapping mesh.
Figure 02 - Difference Between Wrapping Mesh Geometry and Exact Model Geometry
There is no load distribution displayed between the external facade elements in the example shown in Figure 01. The unstressed cells are not displayed according to the color scale for the load distribution, but remain empty. Thus, the value on these elements is 0. This has the advantage that it is recognized immediately that the FE elements are not subjected to a load.The cause of the problem can be visualized directly in RWIND Simulation. By default, the calculations are based on a simplified model there. Depending on the setting, the shell of the model can be refined or coarsened. An FE mesh is placed over the structure and depending on the level of the detail, this FE mesh clings to the model. Figure 02 shows the extent of the level of detail that is too small. The surfaces standing on the façade are not displayed well enough and no wind flows between the cantilevered surfaces in the simulation, which is why these internal surfaces are not subjected to any wind pressure.The level of detail can be adjusted in RWIND Simulation via "Edit Model" or directly in RFEM in the settings for the wind load simulation (see Figure 03). Optionally, the simplified model can also be deactivated completely in RWIND Simulation.In the case of a higher level of detail (corresponds to a finer FE mesh), the cantilevered surfaces are displayed cleanly and the FE elements are stressed accordingly (see Figure 04 and Figure 05).
RWIND Simulation is a program for numerical simulations of wind flow. It is a tool for describing a problem of wind flow around an object, consisting of a system of partial differential equations with the output of an approximate solution on the basis of the finite volume method. Similarly to a simplified model in a real wind tunnel, such a mathematical model provides the information about the wind velocity field and the pressures acting on the surfaces of the wind flow object.
The standards describing the wind effects on buildings and structural components (for example, EN 1991‑1‑4, ASCE/SEI 7, and others) are based on different principles. The rules and standards specify the corresponding instructions for determining wind loads for specific situations and application cases. These formulas are undoubtedly correct for the assigned situations and the resulting values have been confirmed in practice.
However, these guidelines do not describe all situations that occur in the real world of engineers. Here, infinitely different model shapes in the wind flow are processed, whereby each shape has its own high-grade influence on the resulting surface pressures caused by the wind load. However, for all model shapes not mentioned in the respective directives, the equivalent load from wind effects remains unclear.
RWIND Simulation can help here as an auxiliary tool for determining the resulting forces from the wind action. However, despite the use of RWIND Simulation, all requirements of the valid engineering standards must be met. The technology used in the simulation program may also provide further useful insights for sufficiently controlled object shapes.
Figure 01 - Wind Flow Around Complex Antenna System
Figure 02 - Surface Pressures due to Wind Load on Complex Antenna System
AnswerThe new stand-alone program RWIND Simulation provides you with the options for wind simulation and for generating wind loads. The options can be optimally utilized in conjunction with the FEM structural analysis software RFEM or the structural frame analysis software RSTAB.
InputThe direct import of models from RFEM or RSTAB allows you to determine the relevant parameters of the wind directions to be analyzed with height-dependent wind profiles on the basis of a wind standard. This results in the corresponding load cases with globally defined parameters.
You can also run RWIND Simulation manually without RFEM or RSTAB. Furthermore, it is possible to import the data from STL vector graphics.
The import of terrain and buildings of the environment into the simulation is also possible from STL files.
By exchanging the data between RFEM or RSTAB and RWIND Simulation, you can easily use the wind analysis results as load cases in the usual RFEM or RSTAB work environment.
Features of RWIND Simulation
- 3D incompressible wind flow analysis with OpenFoam solvers
- Direct model import of RFEM or RSTAB or STL files
- Simple model changes using Drag and Drop and graphical adjustment assistance
- Automatic corrections of the model topology with shrink wrap networks
- Option to add objects from the environment (buildings, terrain, ...)
- Height-dependent velocity profiles according to the standard
- K-epsilon and K-omega turbulence models
- Automatic mesh generating adjusted to the selected depth of detail
- Parallel calculation with optimal utilization of the capacity of multicore computers
- Results in just minutes for low-resolution simulations (up to 1 million cells)
- Results within a few hours for simulations with medium/high resolution (1‑10 million cells)
- Graphical display of results on the Clipper/Slicer planes (scalar and vector fields)
- Graphical display of streamlines and streamline animation
AnswerIn addition to the manual operation, the website provides a web service (API) for the connection to external programs.The following packages are available for this. The same conditions apply as for manual operation.
- Geo-Zone Tool | 500 queries
- Geo-Zone Tool | 5000 queries
AnswerThe Dlubal online service geo-zone tool for load determination contains zone maps for a quick determination of snow load zones, wind load zones and earthquake zones.
The following packages are available.
- Geo-Zone Tool | 500 Requests
- Geo-Zone Tool | 5000 Requests
This contingent can be used by all employees of your company without any restrictions for all supported maps or load standards.
The Geo-Zone Tool for load determination is continuously extended and supplemented.
Did you find your question?
If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.
Wind Simulation & Wind Load Generation
With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.
The generated wind loads acting on these objects can be imported to RFEM or RSTAB.
“Thank you for the valuable information.
I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. I have used a lot of software with a support contract in the field of structural analysis, but your support is by far the best. ”