General
For imported models, the description RFEM/RSTAB Model is shown in the text box. You can enter any description to characterise the model.
In general, the structural model which you have imported from RFEM or RSTAB represents the Primary model. It includes all objects of the Dlubal application where the wind is to be applied, such as surfaces, beams, solids, and openings. Each project must have exactly one primary model. When generating wind loads for RFEM/RSTAB, the primary model is set to the RFEM/RSTAB model data imported from the Dlubal application (see the Chapter 'Settings').
In addition to the primary model, the RWIND Simulation project can include other models that affect the flow around the primary model. In practice, those secondary models represent surrounding buildings or terrain, for example. Such models can be imported from external files (*.stl) or defined in the RFEM/RSTAB model by means of visual objects or CAD/BIM models (see the Chapter 'Settings'). If you have imported a secondary model, you can position it by drag-and-drop operations or rotate it by using a dialog box or graphical manipulator (see the Chapter 'Edit Objects').
The Terrain Model is a special type of secondary model that differs from other models in two things:
- It can be used as boundary condition, i.e. the bottom boundary of the computational domain.
- Drag forces are not calculated for this model.
If the project contains multiple models, the Drag Force Sum displayed in the legend of the work window (see the Chapter 'Sums of Drag Forces') represents the sum of the forces applied to all models except for the terrain.
The drag force of each individual model can be found on the Info tab of the Edit Model dialog box which belongs to that model (see the Chapter 'Info').
Note
The "M_21BuildingWithTerrain" project in the Demo folder features an example of a terrain model.
The Simplify model option is set as default. It means that small corrections of the RFEM/RSTAB model required at, e.g., boundaries or corners are done automatically by RWIND Simulation (see the Chapter 'Computational Mesh and Model Simplification'). You can control the Level of detail of this simplification by specific levels. Use the slider to adjust it from 0 (very coarse modelling of details with a wide mesh) to 4 (many details with a very fine mesh). The default value 2 represents a good compromise between simplification of the model and calculation speed. Click [Apply] to view and check the simplified model based on a new level of detail.
As a reference, the Detail size of the meshing is shown in the text box below.
The mesh is automatically refined around the model subjected to the wind flow, which contributes to higher calculation efficiency.
Note
Depending on the geometry of the model, it is not always possible to apply high levels of detail. Level "4" settings can slow down the program considerably or may cause insufficient memory errors.
High levels of detail can produce extremely fine or large meshes.
It is then recommended to apply an Optimisation to the mesh in which its shape is preserved. The [Settings] button enables you to control the parameters of this optimisation. A new dialog box appears where you can set the upper and lower limits of the mesh cells to be created.
The Close openings smaller than option enables you to control how openings in the model are to be treated. 0% is preset. That means that all openings or gaps are considered for the analysis. The level of closing openings can either be modified as percentage or set as absolute value. It is thus possible to neglect small openings and simplify the model. Furthermore, window or door openings which are closed in the real model can be easily filled with this feature.
Note
If a beam model represents the structural model of a framework whose surfaces (cladding or roof covering) are not explicitely included in the model, those surfaces are not contained in the imported model of RWIND Simulation either. As a matter of consequence, the wind load will be applied only to the members, not to the surfaces lying in between. The Close openings function is not suitable in this case to replace the surfaces: loads on FE nodes would be created, which cannot be exported to the beam model. They would be missing in the framework.
Note
Since the automatic detection of openings is a demanding topological task, it may be necessary to adjust openings manually.