Fluid Stiction Modeling for Quickly Separating Plates Considering the Liquid Tensile Strength

Abstract

Fluid stiction may significantly influence the dynamic behavior when attempting to quickly separate two plates in close contact. The liquid fluid film, filling the gap between the plates, experiences a pressure drop resulting from an increasing distance, and cavitation may appear if sufficient separation speed and low plate distance are present. In the case of small initial plate separation, fluid tension is known to develop and the stiction force may exceed the maximum stiction force calculated by assuming strictly positive pressures in the fluid film. In this paper, a model for simulating the time dependent fluid stiction phenomenon, including a fluid tensile strength and cavitation effects, is proposed. The model is based on Reynolds theory, and the pressure distribution in the liquid zone is solved analytically for each time step, leading to a computationally efficient model without the need for finite element/volume methods. The considered geometry is two long parallel plates submerged in liquid, as present in many valve applications. The model is compared to experimental measurements, and it is found that the model is able to predict the stiction effect with reasonable accuracy given that proper selections of liquid tensile strength and initial plate distance are made.