Mean Flow Structures Inside the Human Upper Airway

The lattice Boltzmann method (LBM) was used to conduct a direct numerical simulation study of the airflow inside an idealised human upper airway. Results from both a modest resolution (18 million control volumes, 320 Gb data set) and an extreme resolution (148 million control volumes, 800 Gb data set) LBM simulation were compared to those from experimental results (Johnstone, A.: Hot wire measurements in an oropharyngeal pathway. M.Sc. Thesis, Queen’s University, Kingston, ON, Canada, 2002; Johnstone et al., Expt Fluids 37(5): 673–689, 2004). A coarse resolution simulation (2.4 million control volumes, 105 Gb data set) was used to record the entire time-varying flow field; the nature of the mean structures in the three-dimensional flow field was studied using this data set. For the mean statistics, the LBM calculations yield better results than do the Reynolds averaged Navier–Stokes methods (Ball et al., Comput Fluids, 2007); the LBM reproduces significant detail of experimentally observed flow features. The flow is three-dimensional, obviously, and the interrogation of the mean flow structure is found to be unsteady so that sagittal plane and time-integrated measurements alone are insufficient to verify the accuracy of computational predictions of this flow.