45762 KB292 KB0 KB2017Bombač, AndrejPirnar, JernejŠirok, BraneXXXII, 132 str., 30 cmCOBISSID:15782683URN:URN:NBN:SI:doc-8VZKBERNslJ. Pirnarvisokošolska delaairway mechanoreceptorschannel with compliant wallsDisertacijedissertationsdvojno sklopljen sistem fluid-strukturamehanoreceptorji respiratornega sistemaobstructive pharyngeal collapseobstructive sleep apnoeaobstruktivna apneja med spanjemobstruktivna zapora žrelaprožna stena kanalaSindrom apneje v spanjesklopljena računalniška FSI-simulacijasoft palate fluttertrepetanje mehkega nebatwice-coupled fluid-structure systemupper airwayzgornja dihalna potRačunalniška simulacija toka fluida skozi prožni kanal nespecificiranih oblik z aplikacijo na biološkem sistemu| doktorsko delo|Obstructive sleep apnoea (OSA) is a breathing disorder in sleep with immensely multiscale and multifactorial etiology. The disorder is not completely understood yet and requires further attention of researcher in different branches of science. Adopting coupled computational FSI simulation of airflow in human upper airway, an attempt to explain palatal flutter and onset of obstructive pharyngeal collapse was made. The focus was put on the velopharyngeal region where the greatest level of upper airway compliance was estimated to occur. It was showed that during the inspiratory phase of breathing velopharyngeal narrowing due to subatmospheric suction pressure occurs. Conversely, pharyngeal widening was predicted during the expiration because of the positive gauge pressure. As the main attribute of snoring, simultaneous soft palate flutter of frequency 17.8 Hz was predicted. It was shown the evaluated vibrations were not because of the unstableness of the used numerical coupling scheme. When the length scale of observation is reduced the two-phase nature of respiratory fluid flow is exposed. Hence, the twice-coupled system needs to be analysed. The experimental system was developed and built mimicking the fundamental characteristics of the respiratory system - turbulent jet, flow recirculation, and liquid-lined compliant wall. It was demonstrated the damping of shear and pressure fluctuations was increased in consequence of increase in liquid film thickness, viscosity or surface tension. Hence, altering airway surface liquid physical properties, stimuli and activation of mechanoreceptors could be modulated affecting the onset of obstructive sleep apnoeaObstruktivna apneja med spanjem (angl. Obstructive sleep apnoea - OSA) je motnja dihanja v spanju, ki zaradi večnivojskih vzročnih mehanizmov še ni povsem pojasnjena, kar terja nadaljnjo pozornost raziskovalcev različnih strok. S sklopljeno računalniško FSI-simulacijo poskušamo razložiti pojav trepetanja mehkega neba z uvulo in nastanek obstruktivne zapore žrela pri toku zraka skozi zgornjo dihalno pot človeka. Osredinimo se na območje velofarinksa, kjer je podajnost zgornjih dihal najvišja. V fazi vdiha se zaradi subatmosferskega intraluminalnega tlaka pojavi oženje žrela, ob izdihu pa se dihalna pot zaradi nadtlaka razširi. Z računalniško simulacijo napovemo sočasen pojav trepetanja mehkega neba. Frekvenca trepetanja, ki kaže na pojav smrčanja, je enaka 17,8 Hz. Pokažemo, da trepetanje mehkih struktur ni posledica nestabilnosti uporabljene numerične sheme sklopljenja. Ko krajevno skalo opazovanja respiratornega sistema zmanjšamo, razkrijemo, da je tok fluida dvofazen, mehanski sistem pa dvojno sklopljen. Razvijemo in zgradimo fizikalni eksperiment, ki zajema bistvene karakteristike zgornjih dihal - turbulentni curek in recirkulacijo toka ter prožno steno, omočeno s plastjo kapljevinskega filma. Ugotovimo, da se sposobnost dušenja fluktuacij strižne in tlačne obremenitve poveča z večanjem debeline, viskoznosti ali površinske napetosti kapljevinskega filma. S spreminjanjem fizikalnih lastnosti sluzi respiratornega sistema bi zato lahko uravnavali stimulus in aktivacijo mehanoreceptorjev ter posredno vplivali na pojav obstruktivne apneje med spanjemTEXTvisokošolska delatheses and dissertationsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za strojništvo