Particle clustering in renewable energy systems: a spatiotemporal characterisation with Voronoi tessellations and lacunarity

Wind-thrust debris in wind farms and solar photovoltaic (PV) plants induces degradation and threatens production. Turbines suffer blade erosion and forcing due to particle impact. Deposition on PV surfaces blocks light and creates surface-degrading hotspots. Mitigating these effects is difficult, as turbulent structures capture or carry particles depending on inertial effects. Recent studies discuss effects of inertial particles in PV and turbine wakes, including particle path simulations. Yet, little is known about clustering in array wakes, an expected influence on soiling and erosion for PV and wind arrays. Here, particle-laden wind tunnel studies observe clustering patterns in the wake of a model turbine and, separately, a model PV array. Voronoi cell distribution is introduced to identify clusters and voids, and lacunarity analysis quantifies wake-dependent cluster heterogeneity. Varying inflow velocity and particle volume fraction (φ_v), turbine wake cluster persistence (>10D) shows implications for wind farm spacing. For a model PV array, panel wake modification dictates particle distribution for a panel downstream. Together, these studies present novel analysis informing on particle-laden wake physics and highlight the importance of clustering in renewable energy systems.