Beijing Key Laboratory of Green Built Environment and Energy Efficient Technology, Beijing University of Technology, Beijing, China.
School of Resources, Environment and Architectural Engineering, Chifeng University, Chifeng, Inner Mongolia, China.
PLoS One. 2024 Nov 18;19(11):e0313522. doi: 10.1371/journal.pone.0313522. eCollection 2024.
Human breathing is crucial for studying indoor environments and human health. Computational Fluid Dynamics (CFD) is a key tool for simulating human respiration. To enhance the accuracy of CFD simulations and reduce computation time, a new simulation strategy for human respiration is proposed in this paper. The effects of steady versus unsteady boundary conditions on simulation results were examined. For the unsteady boundary, sinusoidal exhalation velocities and non-inhalation gas were assumed, while the steady boundary involved constant velocities during both exhalation and inhalation phases. The jet center trajectory under different boundary conditions was analyzed and compared with experimental data. Additionally, variations in pollutant dispersion near the mouth under the two boundary conditions were discussed. Furthermore, the paper compared the calculation accuracy, calculation time and memory occupied by a single turbulence model or switching flow character models in human respiration simulation. Differences in exhaled gas vorticity and jet penetration depth across different flow models were identified. Finally, combined with the non-iterative algorithm, the optimal strategy of human respiration simulation was proposed. Results show that under the comprehensive consideration of calculation accuracy, calculation time and memory occupancy, using sinusoidal expiratory boundary conditions combined with the PISO algorithm, with the RNG k-ε model during expiratory phase, and switching into the laminar flow during inspiratory phase, is the optimal strategy of simulating human breathing.
人类呼吸对于研究室内环境和人类健康至关重要。计算流体动力学（CFD）是模拟人类呼吸的关键工具。为了提高 CFD 模拟的准确性并减少计算时间，本文提出了一种新的人类呼吸模拟策略。研究了定常与非定常边界条件对模拟结果的影响。在非定常边界条件下，假设呼气速度和非吸气气体呈正弦变化，而定常边界条件则在呼气和吸气阶段均采用恒定速度。分析并比较了不同边界条件下射流中心轨迹与实验数据。此外，还讨论了两种边界条件下污染物在口部附近的扩散变化。进一步比较了在人类呼吸模拟中单一湍流模型或切换流特性模型的计算精度、计算时间和占用内存。确定了不同流动模型下呼出气体涡度和射流穿透深度的差异。最后，结合非迭代算法，提出了人类呼吸模拟的最优策略。结果表明，在综合考虑计算精度、计算时间和内存占用的情况下，采用正弦呼气边界条件并结合 PISO 算法，在呼气阶段使用 RNG k-ε 模型，在吸气阶段切换为层流，是模拟人类呼吸的最佳策略。
