CFD SIMULATION OF A GAS MASK FILTER IN THREE REALISTIC BREATHING PATTERNS

摘要

This research adopts CFD tools to investigate the influence of inspiratory resistance and extra work of breathing towards the users under three realistic breathing patterns (resting, light activity, and moderate exercise). The calculation model adopts the transient Navier-Stokes equation with the low Reynolds number k-ε turbulent model to find the solution. Besides, the momentum loss of porous flow calculated by the porous media equation is added in the source term of the momentum equation to present a larger pressure drop in porous media domain. The simulation results reveal that the maximum inspiratory resistance for Model A_1 under moderate exercise is 2.35 times of light activity and 4.94 times of resting condition. In addition, the maximum of extra breathing work for moderate exercise is 4.83 times of light activity and 19.89 times of resting condition. Under realistic breathing patterns, the changes of the exercise strength in human will lead to the proportional changes in inspiratory resistance and extra work of breathing when wearing the gas mask. Subsequently, the characteristics of the respiratory physiology will be altered and the cardio-pulmonary load of the users will be increased.