Aeroacoustics analysis helps us understand how airflow creates noise. When wind blows past a tall building, it can make annoying whistling or humming sounds. This is a big topic in computational aeroacoustics (CAA) and is very important for architects and city planners. To predict this wind noise, we use a special tool called the Ffowcs Williams and Hawkings (FW-H) model. This FW-H Model CFD approach lets us calculate the sound without building expensive physical models. The wind creates swirling air patterns called vortices. These vortices push and pull on the building, creating sound waves that travel far and can bother people. A good Building Aeroacoustics Fluent study can help lower this noise pollution, making cities much nicer places to live. This report uses the methods from a research paper [1] to show how a Aeroacoustics Analysis On Building Using FW-H Model CFD simulation works.

• Reference [1]: Li, Zhengnong, and Jianan Li. “Numerical simulation study of aerodynamic noise in high-rise buildings.” Applied Sciences19 (2022): 9446.

Simulation Process: Fluent Setup, Grid Generation and Acoustic Model Configuration

We started by creating a 3D model with three high-rise buildings inside a large rectangular space. To get very accurate results, we used ANSYS ICEM software to make a high-quality structured grid. This neat grid helps the computer solve the problem correctly. A very important step was writing a special code, called a User-Defined Function (UDF), for the wind inlet. This UDF creates a realistic wind speed profile, where the wind is slower near the ground and faster higher up. To capture the sound, we activated the FW-H acoustic model in ANSYS Fluent and placed 4 virtual microphones, or receivers, in the simulation to record the noise levels at different spots.

Figure 1: Structured grid generated in ANSYS ICEM for the Building Aeroacoustics CFD analysis.

Post-processing: CFD Analysis, Linking Flow Structures to Predicted Noise Levels

The velocity contour gives a clear, professional visual of the wind blowing around the buildings at a top speed of 31.12 m/s. Behind each building, we can see large blue areas. These are low-speed wake regions where the air is very messy and turbulent. The interaction between the fast-moving wind and these slow, swirling wakes is the main reason why noise is created. These big changes in speed and pressure are exactly what the FW-H Model listens to in order to calculate the sound.

Figure 2: Velocity distribution from the Aeroacoustics CFD simulation, showing wake regions behind the buildings.

The results from receiver 1 tell us what kind of noise the buildings make. The sound is loudest at very low frequencies. The sound pressure level is highest, around 44 dB, at frequencies below 5 Hz. This deep, low-frequency humming sound is typical for wind blowing past large structures. As the frequency gets higher, the noise level drops quickly, down to about 25 dB. The detailed analysis shows a peak sound level of almost 100 dB for sounds below 1 Hz. This professional data confirms that the largest, slowest-moving air swirls are creating the most powerful sound waves. The most important achievement of this simulation is the successful use of the FW-H model to translate complex flow dynamics into a specific noise prediction, accurately identifying that the dominant wind noise occurs at very low frequencies, which is critical information for designing quieter buildings.

Figure 3: Sound pressure level captured by a receiver in the FW-H Model Fluent analysis, showing low-frequency noise dominance.