Fractal Characterization of Cavitation Erosion in Glycerol-Water Mixtures: Role of Viscosity in Aluminum Surface Failure

This study investigates how fluid viscosity modulates cavitation erosion in Al-99.92 aluminum surfaces by employing fractal analysis to quantify degradation patterns in water and glycerol-water mixtures (10–40 cSt). Fractal dimensions, calculated from power spectral density (PSD) slopes of SEM-derived surface topographies, correlate strongly with traditional erosion metrics (mean depth penetration, MDP). Both fractal dimension and MDP exhibit a viscosity-dependent decline, revealing reduced cavitation intensity in high-viscosity fluids. Critically, fractal trends remain scale-invariant across magnifications, confirming that viscosity governs surface texture complexity independently of imaging resolution. Detached particle morphology and surface features (cracks, plastic deformation) identify fatigue failure as the dominant erosion mechanism, with liquid viscosity exerting secondary influence. By bridging fractal metrics to mechanical erosion outcomes, this work establishes fractal analysis as a robust tool for predicting viscosity-dependent cavitation damage in aluminum alloys, offering insights for material selection in high-viscosity hydraulic systems.