Elucidation of Flow Mechanisms Modulating Vehicle Wind Noise by Using Large-Scale CFD Simulation Kobe University

Format:

Book

Conference/Event

Author/Creator:

Tajima, Atsushi, author.

Hirata, Takumi, author.

Ikeda, Jun, author.

Kamiwaki, Takahiro, author.

Wakamatsu, Junichi, author.

Tsubokura, Makoto, author.

Conference Name:

WCX SAE World Congress Experience (2026-04-14 : Detroit, Michigan, United States)

Language:

English

Subjects (All):

Electric vehicles.

Mathematical analysis.

Product development.

Noise.

Vehicle body pillars.

Doors.

Mirrors.

Computational fluid dynamics (CFD).

Turbulence.

Engines.

Local Subjects:

Electric vehicles.

Mathematical analysis.

Product development.

Noise.

Vehicle body pillars.

Doors.

Mirrors.

Computational fluid dynamics (CFD).

Turbulence.

Engines.

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2026

Summary:

In vehicle development, noise reduction is critical for ensuring passenger comfort. As electric vehicles become prevalent and engine noise is minimized, wind noise becomes more noticeable. Modulated wind noise, which causes a sense of fluctuation due to atmospheric turbulence, wind gusts, and preceding vehicle wakes, can cause significant discomfort. This noise is characterized as a high frequency sound above 1 kHz, modulated at low frequencies owing to the wind velocity and direction fluctuating at several Hz. The mechanisms behind wind noise modulation are not fully understood, and no established countermeasures have been developed. This is because wind noise perceived through the side window is primarily caused by the A-pillar vortex and door mirror wake, which coexist as complex turbulent flows around the vehicle. Therefore, identifying the source of modulated wind noise around vehicles under fluctuating wind conditions is difficult. This study aims to identify the source of the modulated wind noise and to clarify the underlying flow mechanisms. Numerical analysis (CFD) was used to simulate windy conditions, where the wind velocity and direction fluctuated at several Hz: successfully reproducing modulated wind noise around the vehicle. Using the modulation power spectrum to quantitatively evaluate the modulated wind noise, the contributions of A-pillar separation and door mirror wake to modulation power were clarified, identifying the source of the modulated wind noise around the vehicle. Additionally, vehicle shape effects were examined, such as door mirror presence and A-pillar modifications, which can suppress modulated wind noise. No significant difference in wind noise modulation power was observed with or without door mirrors, but it was found that the A-pillar shape modification contributed significantly to high frequency noise modulation power. To suppress modulated wind noise, designing an A-pillar shape that minimizes the separation flow, which intensifies owing to crosswind fluctuations, is crucial

Notes:

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