Verificar parâmetros

Para obter os melhores resultados da nossa simulação numérica, é importante verificar alguns pontos importantes antes de realizar o cálculo, os quais são discutidos nas seguintes subsecções.

Detection of Overlapping Triangles

The original model may contain "double triangles", i.e. overlapping triangles that lie in the same plane, see image below.

Malha do modelo original, triângulos sobrepostos

The overlapping triangles can lead to wrong results, because the resulting pressure can be extrapolated to all these triangles and the total drag force acting on the model can be increased by that. The check of overlapping triangles is activated automatically after the model import (see chapter Import Models) or can be run manually from the menu, see Image below.

Verificação da topologia do modelo

When you click on model check, a new window will open where you will find the conclusion and information about the number of overlapping triangles and their area.

Informação de topologia do modelo

Os dados do modelo de triângulos sobrepostos podem ser exportados para um ficheiro e depois visualizados e visualizados no ParaView.

Túnel de vento

The outline of the wind tunnel is displayed as a box around the model in its center. You can check the wind direction, which is symbolized by a big red arrow. In the "Project Navigator," several options are available to display certain items relevant for the wind tunnel (see the image Project Navigator). The terrain level results from the value defined in the "Model Properties" section of the "General Data" window.

Navegador de projetos - Ver

If necessary, you can adjust the size and position of the wind tunnel graphically or in the "Wind Tunnel" dialog box (see Cchapter Wind Tunnel). Make sure that enough space is provided on all sides of the model for the air to flow unimpeded.

Aberturas

If you have selected the "Close openings" option (see Section Mesh Settings), you can check whether the openings or gaps are adequately closed in the RWIND 3 model. If necessary, you can modify the settings in the image Edit Model dialog box of RWIND 3. Note that it will make a considerable difference for the analysis whether the air can flow through an opening or not.

Original Model

The original model is a model created in RFEM 6/RSTAB 9, imported from an external file or created in the Model Editor in RWIND 3. The outer surface of the model (outer shell) is the most important part for external aerodynamics. Before calculation, the outer surface of the model is divided into triangles. A triangulação da superfície do modelo é a base para a criação do modelo simplificado utilizando uma malha de encolhimento, o modelo simplificado é a base para a geração da malha de volume finito no espaço em redor do modelo. The numerical calculation is performed in this finite volume mesh. Although one of the great advantages of RWIND 3 is the possibility of using a simplified model (shrink-wrapping), which eliminates most of the potential problems, still every numerical calculation should be preceded by at least a quick check of the correctness of the geometry of the original model.

Before starting the simulation, we should check the geometry of the original model to ensure that it is not too complex for our purpose and that it does not contain unnecessary parts of the model (for example, inner surfaces, partitions, and so on) that are not important for our numerical simulation (external aerodynamics). Internal surfaces in a closed model (closed volume) increase the computational requirements in terms of both data and time, and can lead to inaccuracies. The more complex the geometry, the more time should be spent on checking the original model mesh and generated finite volume mesh. Para este efeito, o Mesh Inspector tool is used.

Simplified Model

RWIND 3 features a "Simplified Model", which is created from the original RFEM 6 / RSTAB 9 model. It represents a special mesh to define the model boundary (see Chapter Computational Mesh and Model Simplification for further information).

You can display the simplified model as follows:

• Select the "Show Simplified Model" option in the panel.
• Select the "Simplified" option in the "View navigator" for the Model display.

Opções para mostrar o modelo simplificado no navegador Vistas e no painel

The degree of simplification is controlled by the "Level of detail" specified in the "Edit Model" dialog box. Chapter "General" includes an example that shows the effects of this value on the "shrink-wrapping" process applied to the model. If the boundaries are not represented properly, you can adjust the level. When you click in the Edit Model dialog box, you can immediately check the modifications and view the new simplified model. Note that a very detailed model will accordingly require more computational time.