Browsing by Author "Lasota, Martin"
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- ItemLarge-Eddy Simulation for Aeroacoustics of Human PhonationLasota, Martin; ; Šidlof Petr, doc. Ing. Ph.D. Skolitel : 58116Disertační práce se zabývá numerickým modelováním 3D nestlačitelného proudění vzduchu při lidské fonaci pěti kardinálních samohlásek /u, i, textipaA, o, ae/. Vědecký přínos této práce je v popisu souvislosti mezi výpočtem turbulentního proudění při použití konvenčního subgrid modelu (jednorovnicový, WALE), či nově implementovaného anizotropního minimálně disipačního (AMD) subgrid modelu a jeho vlivu na aeroakustický výpočet fonace. Vzhledem k velké škále měřítek v turbulentním proudění a v akustice je simulace rozdělena tak, že výpočet nestlačitelného proudění v hrtanu je realizován metodou konečných objemů na jemné síti a zdroje zvuku včetně šíření zvukových vln od hrtanu až do vyzařovaného prostoru okolo úst metodou konečných prvků na hrubé akustické síti.
- ItemLARGE-EDDY SIMULATION OF FLOW THROUGH HUMAN LARYNX WITH A TURBULENCE GRID AT INLET(ACAD SCI CZECH REPUBLIC, INST THERMOMECHANICS, DOLEJSKOVA 5, PRAGUE 8, 182 00, CZECH REPUBLIC, 2019) Lasota, Martin; Šidlof, PetrThe upcoming paper brings forward some remarks connected with a turbulence initialization at the inlet of a computational domain. The computational domain is a simplified model of human larynx with vocal folds. As a numerical solution of an airflow through the larynx is applied a Large-Eddy Simulation (LES) approach. Our goal was to induce turbulence fluctuations directly in the subglottal area by using a model of a turbulence grid at inlet. The Reynolds numbers encountered in glottal flow lie in the transitional regime.
- ItemLarge-Eddy Simulation of Internal Flow through Human Vocal Folds(Les Ulis: EDP Sciences, 2018) Lasota, Martin; Šidlof, PetrThe phonatory process occurs when air is expelled from the lungs through the glottis and the pressure drop causes flow-induced oscillations of the vocal folds. The flow fields created in phonation are highly unsteady and the coherent vortex structures are also generated. For accuracy it is essential to compute on humanlike computational domain and appropriate mathematical model. The work deals with numerical simulation of air flow within the space between plicae vocales and plicae vestibulares. In addition to the dynamic width of the rima glottidis, where the sound is generated, there are lateral ventriculus laryngis and sacculus laryngis included in the computational domain as well. The paper presents the results from OpenFOAM which are obtained with a large-eddy simulation using second-order finite volume discretization of incompressible Navier-Stokes equations. Large-eddy simulations with different subgrid scale models are executed on structured mesh. In these cases are used only the subgrid scale models which model turbulence via turbulent viscosity and Boussinesq approximation in subglottal and supraglottal area in larynx.