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Home Tutorials A Simple Wind Tunnel

Tutorial 1: a simple wind tunnel.

This first tutorial is very useful to understand the functionality of RBF Morph with a simple and small Fluent model. The geometry investigated is a very simplified external aerodynamic problem: a bluff body (a perfect cube with edges of 1m) is immersed into a virtual wind tunnel (10m long, 5m wide, 3m high) located at 3m from the inlet and at 6m from the outlet.

The aim of this tutorial is to study the effect of cube position and attitude angle, first as individual solutions and then combining them.

Step 1: translating the cube

The position of the body along the wind tunnel is a very important topic: in the original mesh the cube is closer to the inlet because the flow pattern in the undisturbed area can be captured easier than in the wake region. A movement along the x direction of the cube is desired. This task can be completed in several ways. The simpler approach used in this tutorial uses only surfaces for the definition of the source points. All the mesh nodes that belong to the cube are used to define a first set of source points prescribing a rigid movement. All the nodes that belong to the tunnel, the inlet and the outlet are used to define a second set of source points prescribing a null rigid movement. All the areas without a prescribed motion are left deformable by default: the ground and all the volume mesh.

Step 2: rotating the cube

The effect of the attitude angle of the cube is very important. Even a slight modification in the attitude angle can change the flow field, especially in the wake. This kind of analysis requires the full model because an asymmetric geometry and flow field is produced. This modifier can be introduced with a slight modification of the modifier described in Step 1 for the translation of the cube.

Step 3: combining different solutions

In this tutorial the advanced feature of Multi-Sol is explored. Multi-Sol can be used in both interactive and batch mode. It basically performs the task of combining several solutions together, superimposing them, i.e. the displacements of each solution are always calculated on the original mesh and then summed to obtain the final deformed configuration.This tool is very efficient because allows to use the stored modifiers without rebuilding the solution and can be used in parallel.

This advanced feature is available in both in serial and in parallel, using the GUI panel Multi-Sol or using the TUI command (rbf-morph). The GUI is very useful to predict in advance the effect of the modifiers combination and to preview the mesh, while DOE and optimisation tasks can be easily performed in batch thanks to the TUI command (rbf-morph) that transforms the original Fluent mesh in a true parametric CFD model.

 


 
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