Modelling and numerical solution of variable orifice flow meter for application of respiratory

This study investigates three-dimensional computational fluid dynamics (CFD) analysis related to Variable Orifice Flowmeters (VOFM) used in mechanical ventilators. The analysis employed a dynamic fluid-structure interaction (FSI) approach, utilizing the finite volume method (FVM). A comprehensive numerical simulation was performed using two turbulence k-ω SST model. The CFD methodology was validated by examining the flow characteristics of flexible membranes making triangular and circular orifice plates. Validation was achieved by comparing the numerical results with previously published experimental data, revealing several high correlation factors that describe the deflection of the flexible membrane, drag coefficient, and pressure drop in relation to the mass flowrate. The findings indicate that both the thickness and shape of the orifice play a crucial role in influencing pressure drop and deflection. Notably, the circular model exhibits more linear behaviour and greater sensitivity compared to the triangular model.