Microleakage Prediction and Experimental Validation of Three Equivalent Microscopic Interfaces Based on the Lattice Boltzmann Method

Abstract Microleakage arising from microscopic surface defects or elastic deformation at sealing interfaces can compromise system integrity, reduce efficiency, and pose safety risks. To address this challenge, a high-order lattice Boltzmann model (LBM) incorporating Knudsen-number-dependent boundary conditions is developed to predict gas leakage in the transitional flow regime (0.1 < Kn < 1). The model captures the influence of surface morphology on microscale gas transport using three geometrically equivalent microscopic channel interfaces—triangular, frequency-doubled triangular, and sinusoidal—constructed under identical amplitude and blockage ratio conditions. Two characteristic parameters, the effective slip length (beff) and coherence length (Lc), are introduced to quantitatively describe the modulation of near-wall momentum transfer by surface topography. A helium microleakage test rig is established to validate the model experimentally under inlet pressures ranging from 0.1 to 7.5 MPa at room temperature. The results show that the triangular and frequency-doubled triangular channels exhibit similar flow behavior, whereas the sinusoidal channel exhibits pronounced slip enhancement near the outlet. The proposed model successfully achieves a closed-loop verification linking surface morphology equivalence, noncontinuum flow, and leakage rate, establishing a reliable predictive framework for metal seal design and microleakage evaluation.