Shear Evolution and Slippage of the Liquid-Liquid Interface over a Liquid-Infused Surface: A Many-Body Dissipative Particle Dynamics Study

The liquid-liquid interface (LLI), which is the key to cause flow slippage and thus promote drag reduction of liquid-infused surfaces (LISs), does suffer from the action of flow shear. In the current study, the transverse many-body dissipative dynamics simulation method is applied to explore the shear evolution of LLI and the corresponding slippage over a periodically grooved LIS. Results show that a relatively small shear rate only induces a slight deformation of LLI and the corresponding effective slippage is dependent on the shear rate. With a further increase of the shear rate, LLI deforms apparently and then the downstream three phase contact line depins to move once the balance between the capillary force and the shear force is broken, which results in an apparent increase of the slippage, specifically for a convex LLI. Compared with a convex LLI or a concave LLI, a flat LLI remains relatively stable under the same shear action, and an increase of the viscosity ratio and a decrease of the LLI fraction can both strengthen the shear resistance of an LLI, while they are less effective to promote the slippage. Consequently, the current results not only indicate that the slippage is related to the interface deflection and the shear rate but also suggest that both the shear resistance and the slippage of LLI should be considered when designing an effective LIS.