title: A new adaptive time step method for unsteady flow simulations in a human lung.
abstract: The innovation presented is a method for adaptive time-stepping that allows clustering of time steps in portions of the cycle for which flow variables are rapidly changing, based on the concept of using a uniform step in a relevant dependent variable rather than a uniform step in the independent variable time. A user-defined function was developed to adapt the magnitude of the time step (adaptive time step) to a defined rate of change in inlet velocity. Quantitative comparison indicates that the new adaptive time stepping method significantly improves accuracy for simulations using an equivalent number of time steps per cycle.
authors.affiliation: a HUCA , University of Oviedo , Oviedo , Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Fenández-Tena
authors.affiliation: b Department of Graphical Expression , University of Extremadura , Badajoz , Spain.
authors.forename: Alfonso C
authors.initials: AC
authors.lastname: Marcos
authors.affiliation: a HUCA , University of Oviedo , Oviedo , Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Martínez
authors.affiliation: c School of Aerospace and Mechanical Engineering , University of Oklahoma , Norman , OK , USA.
authors.forename: D
authors.initials: D
authors.lastname: Keith Walters
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008168:Lung / Q000502:physiology*; D009716:Numerical Analysis, Computer-Assisted; D012212:Rheology; D013147:Spirometry; D013997:Time Factors
keywords: Adaptive time step; CFD; unsteady flow rate