Three-dimensional effects of the wake on wind turbine sound propagation using parabolic equation

Bommidala, H.; Colas, J.; Emmanuelli, A.; Dragna, D.; Khodr, C.; Cotté, B.; Stevens, R.J.A.M.

doi:10.1016/j.jsv.2025.119036

Publication 118 · Wind-energy acoustics

Three-dimensional effects of the wake on wind turbine sound propagation using parabolic equation

H. Bommidala, J. Colas, A. Emmanuelli, D. Dragna, C. Khodr, B. Cotté, R.J.A.M. Stevens, J. Sound Vib. 608, 119036 (2025).

Read the article Open-access version (university repository)

Main finding

Lateral gradients of streamwise wake speed refract turbine sound into three-dimensional caustics whose position varies with source height in the model. The calculations do not validate the focal magnitudes or establish a general stability or annoyance rule.

Sound pressure fields from three-dimensional and stacked two-dimensional propagation models for three stabilities — **How to read the figure.** Sound pressure behind a wind turbine computed with a fully three-dimensional parabolic equation (top row) and with stacked two-dimensional solutions (bottom row), for stable, neutral and unstable conditions. The stacked approach omits horizontal refraction, so the difference between the rows is what refraction across a long, laterally sheared wake does. The focal magnitudes are model output rather than validated levels, and no general rule about stability or annoyance follows from them. Open the full-resolution figure. Figure 23. H. Bommidala et al. (2025). No separate licence is stated here; consult the original publication and credited source before reuse.

Why this matters

Lateral wake gradients can refract turbine sound sideways into three-dimensional caustics whose position depends on source height.

Research context

Wind turbine sound propagation (read the finding) compares PE and LEE in two dimensions; Impact of a Two-Dimensional Steep Hill on Wind Turbine… (read the finding) shows source-height-dependent wake focusing with N×2D. Later papers, Modeling wind farm noise emission and propagation (read the finding) and Wake-induced variations in noise levels and amplitude modulation for… (read the finding), use N×2D for stable farm and turbine-pair cases. They inherit the dimensionality warning, but the quantitative error reported here cannot be transferred unchanged.

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