CFD Simulation of Airfoil Aerodynamics in SolidWorks: Flow Over a NACA Airfoil

Welcome back to our CFD Simulation Using SolidWorks series! In this blog, we’ll walk through how to simulate flow over a NACA airfoil using SolidWorks. This exercise is a great way to dive deeper into computational fluid dynamics basics and apply what you’ve learned so far. 

This tutorial will also give you a hands-on understanding of how airfoils interact with fluid flow, making it an essential practice for those pursuing a computational fluid dynamics course. Let's jump right in! 

Step 1: Creating the NACA Airfoil Geometry 

To begin, we'll need to create the airfoil geometry. We’ll use the NACA airfoil data in this project, and it helps to better understand the CFD basics for mechanical engineers. 
1. Create a New Project: Start by creating a new part file. 
2. Insert the Airfoil Curve: Go to Insert > Curves > Curve Through XYZ Points. This option allows you to input the NACA airfoil data that we’ll be using. Click on Browse, select text files, and load the provided NACA airfoil data file. You can use this data file to ensure we're all simulating the same airfoil. 
3. Generate the Airfoil: After loading the file, SolidWorks will populate the points and generate the airfoil curve. Zoom out to see the generated airfoil, and you’ll notice that it’s currently at 0 degrees angle of attack (meaning the airfoil is not tilted). 

4. Close the Loop: Use the Line Tool to close the airfoil contour. This step is important as it completes the geometry required for the simulation. 
5. Set the Angle of Attack: To modify the angle of attack, select Move Entities and choose Rotate Entities. Use the origin as the rotation point and rotate the airfoil to an angle of 10 degrees for our simulation. This represents a 10-degree angle of attack, which is common in airfoil testing. 

Step 2: Setting Up the Flow Simulation 

Now that we’ve set up the airfoil geometry, we’re ready to move on to CFD using SolidWorks. This will include setting up boundary conditions, flow parameters, and mesh. 

1. Start the Flow Simulation Wizard: Open the Flow Simulation Wizard and name the project something like Angle of Attack Analysis. 
2. External Flow and Time-Dependent Simulation: For this simulation, we’re using external flow because we are simulating air flowing around the airfoil. We’ll also set it up as a time-dependent simulation (or transient simulation), where we run the simulation for 5 seconds and get outputs every 1 second. This will allow us to track how the flow develops over time. 

1. Fluid Selection: The working fluid is air. We’ll set the flow velocity along the X-axis to 600 m/s, which represents a high-speed airflow over the airfoil. 
2. 2D Simulation Setup: Since we're focusing on the XY plane for this simulation, we’ll run a 2D simulation by neglecting gradients along the Z-axis. This simplification speeds up the process without compromising accuracy for this type of analysis.  

Step 3: Setting Up the Computational Domain 

After defining the project, the next step is adjusting the computational domain. 

1. Edit the Computational Domain: Right-click on the domain and click Edit Definition. Adjust the domain size to ensure the flow has enough space to develop properly. A common rule is to have at least 10-15 times the chord length between the airfoil and the outflow boundary. 
2. Wake Region Consideration: The region behind the airfoil, known as the wake region, must be sufficiently long. Ensure that the exit boundary is placed far enough from the airfoil (at least 10-15 times the chord length) to capture the flow separation and wake effects accurately. 

Step 4: Defining Global and Surface Goals 

Goals help us track important flow characteristics, such as forces acting on the airfoil. For this simulation, we’ll focus on the drag force and lift force. 

1. Set Global Goals: First, we’ll track the total force along the X-axis (drag force) and the Y-axis (lift force). These global goals help us monitor the overall forces acting on the airfoil. 
2. Set Surface Goals: Right-click on the airfoil surface and set the same goals—integrating the force along the X and Y axes for the airfoil surface. This will help in calculating the lift and drag coefficients, which are vital for aerodynamic analysis. 

Step 5: Mesh Setup 

A well-defined mesh is crucial for accurate CFD simulations using SolidWorks. For external flow problems, refining the mesh near the airfoil surface is critical, as it captures boundary layer effects and flow separation more accurately 

1. Show Basic Mesh: Start by viewing the basic mesh, which gives an overview of the cell distribution across the domain. 
2. Insert Local Mesh Refinement: Refine the mesh specifically around the airfoil. This local mesh refinement ensures smaller cells near the surface, providing better resolution of the boundary layer and other critical flow regions. 
3. Use of Cartesian Mesh: SolidWorks uses a cut-cell Cartesian mesh by default. While not the most ideal for external flows, it works well for basic simulations. Refining the mesh further would improve the accuracy of results, near the airfoil. 

Step 6: Running the Simulation 

Once the mesh is set, you’re ready to run the simulation. 

1. Start the Simulation: Click Run and use all available processors (for faster computation). As the simulation progresses, you can monitor the evolution of pressure and velocity fields in real-time. 
2. Check Convergence: Pay attention to whether key parameters, such as drag force and lift force, are converging to steady values. While residuals are a good indicator of equation accuracy, watching the behavior of physical quantities like lift and drag is a more reliable way to assess convergence. 

Step 7: Analyzing the Results 

Once the simulation has completed, it’s time to analyze the results. SolidWorks allows you to visualize data using cut plots and goal plots. 

1. Create Cut Plots: Insert cut plots along the XY plane to visualize key variables like velocity magnitude and pressure distribution. These plots provide a detailed look at how the flow behaves around the airfoil. 
2. Refining the Plot: To get smoother contour plots, increase the number of color segments. This adjustment will make the plot easier to interpret. 
3. Analyze Lift and Drag Forces: Look at the surface-integrated forces along the X and Y axes. These represent the drag force and lift force acting on the airfoil. You can calculate the lift and drag coefficients based on these values, which are crucial for evaluating the airfoil's aerodynamic performance. 

Step 8: Advanced Challenge: Angle of Attack Analysis 

As part of your learning process, try this challenge: 

1. Change the Angle of Attack: Adjust the angle of attack incrementally until the stall condition is reached. 
2. Analyze Lift and Drag: For each angle of attack, calculate the lift and drag forces. Plot the lift coefficient and drag coefficient against the angle of attack to study how aerodynamic forces change as the airfoil angle varies. 

This exercise mirrors what you'll learn in Skill-Lync’s Full Course on CFD using SolidWorks, where you'll delve deeper into more complex simulations and analysis techniques. 

Conclusion 

In this blog, we explored how to simulate flow over a NACA airfoil using SolidWorks Flow Simulation. We covered the complete workflow—from setting up the geometry and boundary conditions to running the simulation and analyzing the results. This tutorial also introduced important concepts from Skill-Lync CFD Course, including how to handle CFD basics for mechanical engineers. 

Whether you're new to CFD or looking to refine your skills, Skill-Lync SOLIDWORKS Training offers an excellent pathway to mastering these techniques. I hope this guide was insightful and practical. See you in the next blog, where we’ll explore even more advanced CFD simulations! 

Stay tuned, and happy simulating! 

This blog is part of our ongoing series on CFD Simulations using SolidWorks.   

If you missed the previous posts, check them out here. 

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