Numerical simulation of Interfacial topology over natural superhydrophobic surfaces

Natural superhydrophobic surfaces (nSHS), such as those on lotus and salvinia leaves, provide an evolutionary blueprint for advanced drag-reducing materials. Understanding how the intricate micro/nanostructures of these surfaces maintain air entrapment under varying pressures is crucial for engineering durable synthetic analogues. However, predictive modeling is limited by the challenge of accurately representing these complex 3D topographies and the resulting fluid interface dynamics. In this pioneering study, we address this gap by developing high-resolution numerical models of natural SHS, including lotus, salvinia, and rice leaves, based on their measured microscale geometries. We employ a variational level set method to simulate the topology of the air-water interface as a function of applied pressure. Our simulations provide a detailed statistical description of the interface, quantifying the volume of entrapped air and the liquid-solid contact area for each surface. We compare and contrast the stability of the air-water interface across the different leaf structures, revealing distinct responses to increasing pressure. These results elucidate the structure-function relationships that govern the robustness of the Cassie-Baxter state on each natural surface, presenting a powerful tool for the numerical simulation and optimization of bio-inspired surfaces for a wide range of engineering applications.