As the world and especially Paris gets ready for the 2024 Olympic Games, there is a monument that everyone in attendance will surely see, the historic Eiffel Tower. In celebration of the games and the host country, we will be using SOLIDWORKS Flow Simulation to analyze the airflow around the tower while it is adorned with the Olympic Rings.
How to setup the analysis
We will be discussing the basics of the setup and the different ways to approach meshing a problem like this one.
First, let’s talk about the basics of setting up an external airflow analysis. We walked through the set-up wizard, with the analysis type set to external, default fluid set to air, and the most important part, our initial ambient conditions where we defined to airspeed as 40 MPH.
Now let’s talk about defining our computational domain for our problems’ needs. When doing external airflow studies it is really easy to size the domain incorrectly, whether that is too large or too small. The goal is to size the domain to capture our area of concern, for our purposes, we want to see airflow interaction with the tower and how the flow field starts to develop after the tower. Because we are looking at 1 directional flow we are going to restrict the flow field close to the sides of the tower, and have most of our domain area behind the tower.
Next, let’s talk about the three stages of meshing a problem like this.
- Basic Mesh
- Geometry Based Meshing
- Solution Adaptive Meshing
In Flow Simulation we used a cartesian-based meshing system that creates a 3D grid in the x, y, z directions. This is the initial size for the computational domain, this is where sizing the domain too large can cost you computational resources on meshing areas that are not important for the calculation.
Geometry-based Meshing in SOLIDWORKS Flow Simulation
Geometry-based meshing is exactly what it sounds like. This is where the mesher looks at the existing CAD geometry and based on the settings will refine fluid, solid, and fluid/solid boundary cells around the geometry. If your model has complex geometry with many small features, thin walls, or narrow channels, we will use a geometry-based meshing approach.
Solution Adaptive-based Meshing in SOLIDWORKS Flow Simulation
Solution Adaptive-based meshing is a powerful technique that will refine the mesh density during the calculation of the analysis. The Solution Adaptive method refines the cells around areas with high flow gradients and will automatically refine the mesh in these areas to help improve result accuracy. This can be utilized intentionally before the start of a calculation or turned on during the middle of one to help improve accuracy without having to restart the calculation from the beginning.
To use the Solution Adaptive-based meshing, we will go through the calculation control options menu, which can be reached by right-clicking on the input data folder > calculation controls options > refinement tab. We can also activate this option during the calculation time as well by navigating through the calculation tab on the solver window.
Below is an image of a purely Geometry-based mesh utilizing the automatic settings. While still providing some insight about how a 40 MPH wind will interact with the tower, there is still not enough detail in the mesh to see the fluid-solid interaction. While we could use the manual mesh controls to get better detail around the channels and solid features, it would not capture the wakes developing behind the tower where there is no geometry.
Below is an example of the same setup, utilizing the Solution Adaptive method. As you can can see the mesh is much denser and is refined in a more organic manner due to being based on wakes that are developing around the tower. We will show two methods of implementing the Solution Adaptive method on this model.
Zoomed Image from Above
Remember, the choice between Geometry-Based Meshing and Adaptive Wake Refinement isn’t always clear-cut. Often, a combination of both methods is used. The initial mesh is created using Geometry-Based Meshing, and then Adaptive Wake Refinement is applied during the simulation where necessary. This approach leverages the strengths of both methods, providing a balance between accuracy and computational efficiency. It’s always a good idea to experiment with different settings in SOLIDWORKS Flow Simulation and approaches to find what works best for your specific simulation.
Look out for more content on these topics as we will be going more in-depth. And Good luck to all of the athletes participating in the 2024 Olympic Games!
