Cavitation Bubble Collapse over a Solid Surface: A Numerical Approach Incorporating Surface and Flow Variations

The bubble collapse over a stainless steel surface under four distinct conditions: (i) surface inclination (α = 0°, 15°, and 30°), (ii) surface motion (U = 0, 50, and 75 m/s), (iii) surface roughness (Ks = 0, 0.015, and 0.030 mm), and (iv) multiple bubble interactions (bubble separation, s = 0, 1, and 2 mm) is investigated. The simulations were carried out using ANSYS Fluent software, applying the volume-of-fluid (VOF) approach to monitor bubble dynamics and estimate the pressure distribution. Two standoff distances d/Rmax = 0.97 and 1.42, where d is the distance from the bubble center to the rigid surface and Rmax is the maximum radius of the bubble taken as 3.5 mm, are used. The results show that surface inclination reduces the peak collapse pressures owing to oblique shockwave interactions, with the pressures decreasing by 38.24% at α = 30° as compared to a normal surface. Surface motion enhances collapse asymmetry, reducing the peak pressures by 34.57% at U = 75 m/s, particularly, at d/Rmax = 0.97. An increase in in the surface roughness significantly lowers the localized pressure by 27.75% at a roughness height of 0.030 mm. In multiple bubble interactions, s = 0 generates up to 8.73 × 106 Pa; however, this pressure decreases by over 60% at s = 2 mm, highlighting the influence of bubble spacing on the collapse intensity. These findings provide critical insights into bubble dynamics, erosion mechanisms, and material resilience and offer design guidelines for marine and industrial applications involving cavitation.