Drag reduction of stable biomimetic superhydrophobic steel surface by acid etching under an oxygen-sufficient environment

Abstract

Superhydrophobic surfaces have shown utility applications in drag reduction field. A novel method based on simulation analysis and test experiments is proposed to fabricate a superhydrophobic surface with 3D flower-like micro and nano-structures on a steel ball under an O 2 rich environment. The superhydrophobic steel surface has water CA of 166±1.5°. The sliding angle is less than 2°. The experiment and the simulation of the superhydrophobic and the untreated steel ball fall under water are built to prove the validity of the method of reducing water resistance. The drag reduction ratio of the superhydrophobic steel ball is beyond 53% opposed to the untreated surface under water. A model simulation is built to simulate and analyze the solid-liquid interface drag reduction mechanism of superhydrophobic surface based on theoretical analysis. The result testifies the rationality of the drag reduction experiment.

Focus on Bioinspired Textured Surfaces toward Fluid Drag Reduction: Recent Progresses and Challenges

“…By recording the time it takes for the ball to fall in water, the drag of the ball in the water can be obtained by subtracting gravity and buoyancy from the calculated resultant force, which is called the falling ball drag reduction experiment. [178] Monfared and Alidoostan attached a tower at the end of the model to make the model move in the water. In the rectangular towing tank, the drag on the driving model was measured by a dynamometer at a constant speed.…”

“…[60] An SHS of aluminum foil was prepared by a new onestep hydrothermal method proposed by Tuo et al [94] SHS steel balls with 3D flower-like micro-and nanostructures were fabricated by the oxygen wet oxidation method. [178] The melt hot Figure 11. A) Fabrication of microgroove structure by low-speed wire cutting.…”

“…By recording the time it takes for the ball to fall in water, the drag of the ball in the water can be obtained by subtracting gravity and buoyancy from the calculated resultant force, which is called the falling ball drag reduction experiment. [ 178 ]…”

The challenges, achievements and applications of submersible superhydrophobic materials

“…Rong et al fabricated complex ''flower-like'' micro and nanostructures (similar to that of the lotus leaf) onto steel balls using acid etching and oxidation. 203 The treated steel ball had a visibly higher velocity than an untreated ball when moving through water and by calculation using falling time and water volume gave an overall drag reduction of 84.06%. Additional simulations to prove the validity of the experiment using 3D models in laminar conditions showed the highest drag reduction ratio to be 63.4%.…”

Recent Developments of Superhydrophobic Surfaces (SHS) for Underwater Drag Reduction Opportunities and Challenges

“…Generally, the etching techniques used in the preparation of materials for drag reduction include wet etching and dry etching. Rong et al [97] prepared micro-nanostructures on steel balls by acid oxidation etching, which showed superhydrophobicity after fluorination treatment. The steel balls had a maximum drag reduction effect of 63.4% compared with untreated steel balls.…”