{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T00:37:56Z","timestamp":1760143076470,"version":"build-2065373602"},"reference-count":35,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2024,1,17]],"date-time":"2024-01-17T00:00:00Z","timestamp":1705449600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003093","name":"Ministry of Higher Education Malaysia","doi-asserted-by":"publisher","award":["FRGS\/1\/2020\/TK0\/UNIMAP\/03\/26"],"award-info":[{"award-number":["FRGS\/1\/2020\/TK0\/UNIMAP\/03\/26"]}],"id":[{"id":"10.13039\/501100003093","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Computation"],"abstract":"<jats:p>Obstructive sleep apnea (OSA) is a common medical condition that impacts a significant portion of the population. To better understand this condition, research has been conducted on inhaling and exhaling breathing airflow parameters in patients with obstructive sleep apnea. A steady-state Reynolds-averaged Navier\u2013Stokes (RANS) approach and an SST turbulence model have been utilized to simulate the upper airway airflow. A 3D airway model has been created using advanced software such as the Materialize Interactive Medical Image Control System (MIMICS) and ANSYS. The aim of the research was to fill this gap by conducting a detailed computational fluid dynamics (CFD) analysis to investigate the influence of cross-sectional areas on airflow characteristics during inhale and exhale breathing in OSA patients. The lack of detailed understanding of how the cross-sectional area of the airways affects OSA patients and the airflow dynamics in the upper airway is the primary problem addressed by this research. The simulations revealed that the cross-sectional area of the airway has a notable impact on velocity, Reynolds number, and turbulent kinetic energy (TKE). TKE, which measures turbulence flow in different breathing scenarios among patients, could potentially be utilized to assess the severity of obstructive sleep apnea (OSA). This research found a vital correlation between maximum pharyngeal turbulent kinetic energy (TKE) and cross-sectional areas in OSA patients, with a variance of 29.47%. Reduced cross-sectional area may result in a significant TKE rise of roughly 10.28% during inspiration and 10.18% during expiration.<\/jats:p>","DOI":"10.3390\/computation12010016","type":"journal-article","created":{"date-parts":[[2024,1,17]],"date-time":"2024-01-17T04:16:56Z","timestamp":1705465016000},"page":"16","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Computational Fluid Dynamics Analysis of Varied Cross-Sectional Areas in Sleep Apnea Individuals across Diverse Situations"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4911-8320","authenticated-orcid":false,"given":"W. M.","family":"Faizal","sequence":"first","affiliation":[{"name":"Faculty of Mechanical Engineering & Technology, University Malaysia Perlis, 02600 Arau, Perlis, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4831-7416","authenticated-orcid":false,"given":"C. Y.","family":"Khor","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering & Technology, University Malaysia Perlis, 02600 Arau, Perlis, Malaysia"}]},{"given":"Suhaimi","family":"Shahrin","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering & Technology, University Malaysia Perlis, 02600 Arau, Perlis, Malaysia"}]},{"given":"M. H. M.","family":"Hazwan","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering & Technology, University Malaysia Perlis, 02600 Arau, Perlis, Malaysia"}]},{"given":"M.","family":"Ahmad","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering & Technology, University Malaysia Perlis, 02600 Arau, Perlis, Malaysia"}]},{"given":"M. N.","family":"Misbah","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering & Technology, University Malaysia Perlis, 02600 Arau, Perlis, Malaysia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3744-4935","authenticated-orcid":false,"given":"A. H. M.","family":"Haidiezul","sequence":"additional","affiliation":[{"name":"Faculty of Mechanical Engineering & Technology, University Malaysia Perlis, 02600 Arau, Perlis, Malaysia"}]}],"member":"1968","published-online":{"date-parts":[[2024,1,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"11455","DOI":"10.1038\/s41598-019-47596-5","article-title":"Correlations between obstructive sleep apnea and adenotonsillar hypertrophy in children of different weight status","volume":"9","author":"Wang","year":"2019","journal-title":"Sci. Rep."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1016\/j.jsmc.2018.10.002","article-title":"Weight Management in Obstructive Sleep Apnea: Medical and Surgical Options","volume":"14","author":"Tham","year":"2019","journal-title":"Sleep Med. Clin."},{"doi-asserted-by":"crossref","unstructured":"Corda, J.V., Shenoy, B.S., Ahmad, K.A., Lewis, L., Prakashini, K., Khader, S.M.A., and Zuber, M. (2022). Nasal airflow comparison in neonates, infant and adult nasal cavities using computational fluid dynamics. Comput. Methods Programs Biomed., 214.","key":"ref_3","DOI":"10.1016\/j.cmpb.2021.106538"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"862","DOI":"10.1590\/1806-9282.63.10.862","article-title":"Obstructive sleep apnea syndrome among obese individuals: A cross-sectional study","volume":"63","author":"Modena","year":"2017","journal-title":"Rev. Assoc. Med. Bras."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1702616","DOI":"10.1183\/13993003.02616-2017","article-title":"Challenges and perspectives in obstructive sleep apnoea: Report by an ad hoc working group of the Sleep Disordered Breathing Group of the European Respiratory Society and the European Sleep Research Society","volume":"52","author":"Randerath","year":"2018","journal-title":"Eur. Respir. J."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"744","DOI":"10.1016\/j.chest.2017.06.011","article-title":"Personalized Management Approach for OSA","volume":"153","author":"Carberry","year":"2018","journal-title":"Chest"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"313","DOI":"10.1016\/j.anl.2021.10.007","article-title":"Obstructive sleep apnea\u2014Consideration of its pathogenesis","volume":"49","author":"Suzuki","year":"2022","journal-title":"Auris Nasus Larynx"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/j.otpol.2013.04.003","article-title":"Role of adenotonsillectomy in OSAS children and behavioural disturbance","volume":"67","author":"Passali","year":"2013","journal-title":"Otolaryngol. Pol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"e70","DOI":"10.1164\/rccm.201807-1326ST","article-title":"The Role of Weight Management in the Treatment of Adult Obstructive Sleep Apnea. An Official American Thoracic Society Clinical Practice Guideline","volume":"198","author":"Hudgel","year":"2018","journal-title":"Am. J. Respir. Crit. Care Med."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.jsmc.2018.10.007","article-title":"Volumetric Tongue Reduction for Obstructive Sleep Apnea","volume":"14","author":"Lin","year":"2019","journal-title":"Sleep Med. Clin."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"272","DOI":"10.1186\/s12931-020-01532-8","article-title":"Upper airway lengthening caused by weight increase in obstructive sleep apnea patients","volume":"21","author":"Lin","year":"2020","journal-title":"Respir. Res."},{"key":"ref_12","first-page":"583","article-title":"Computational Analysis of Airflow in Upper Airway under Light and Heavy Breathing Conditions for a Realistic Patient Having Obstructive Sleep Apnea","volume":"128","author":"Faizal","year":"2021","journal-title":"Comput. Model. Eng. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1016\/j.jcms.2020.02.007","article-title":"Effects of surgically assisted rapid maxillary expansion on the modification of the pharynx and hard palate and on obstructive sleep apnea, and their correlations","volume":"48","author":"Vinha","year":"2020","journal-title":"J. Craniomaxillofac. Surg."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"36","DOI":"10.1186\/s43163-021-00105-w","article-title":"Adolescent and adult laryngotracheal stenosis: A review","volume":"37","author":"Klopper","year":"2021","journal-title":"Egypt. J. Otolaryngol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"187","DOI":"10.1016\/S0021-9150(03)00286-7","article-title":"TLR4 Asp299Gly polymorphism is not associated with coronary artery stenosis","volume":"170","author":"Yang","year":"2003","journal-title":"Atherosclerosis"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"701","DOI":"10.1093\/bja\/aei229","article-title":"Effects of helium on high frequency jet ventilation in model of airway stenosis","volume":"95","author":"Buczkowski","year":"2005","journal-title":"Br. J. Anaesth."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"E141","DOI":"10.1002\/lary.26954","article-title":"Investigating the effects of laryngotracheal stenosis on upper airway aerodynamics","volume":"128","author":"Cheng","year":"2018","journal-title":"Laryngoscope"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1679","DOI":"10.1007\/s10237-020-01299-3","article-title":"Investigation of inhalation and exhalation flow pattern in a realistic human upper airway model by PIV experiments and CFD simulations","volume":"19","author":"Xu","year":"2020","journal-title":"Biomech. Model. Mechanobiol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"303","DOI":"10.1134\/S0869864320020122","article-title":"Numerical simulation of particle deposition in the human nasal cavity","volume":"27","author":"Ganimedov","year":"2020","journal-title":"Thermophys. Aeromechanics"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1016\/j.clinbiomech.2017.10.011","article-title":"Assessing the relationship between movement and airflow in the upper airway using computational fluid dynamics with motion determined from magnetic resonance imaging","volume":"66","author":"Bates","year":"2019","journal-title":"Clin. Biomech."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"726","DOI":"10.1136\/thx.2009.131094","article-title":"The effect of mandibular advancement on upper airway structure in obstructive sleep apnoea","volume":"65","author":"Chan","year":"2010","journal-title":"Thorax"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"966","DOI":"10.1016\/j.sleep.2011.08.004","article-title":"Patterns in pharyngeal airflow associated with sleep-disordered breathing","volume":"12","author":"Powell","year":"2011","journal-title":"Sleep Med."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"895","DOI":"10.1016\/j.ajodo.2017.08.027","article-title":"Fluid structure interaction simulations of the upper airway in obstructive sleep apnea patients before and after maxillomandibular advancement surgery","volume":"153","author":"Chang","year":"2018","journal-title":"Am. J. Orthod. Dentofac. Orthop."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"e01461","DOI":"10.1016\/j.heliyon.2019.e01461","article-title":"Development of a hybrid CFD-PBPK model to predict the transport of xenon gas around a human respiratory system to systemic regions","volume":"5","author":"Haghnegahdar","year":"2019","journal-title":"Heliyon"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"663","DOI":"10.1016\/j.joms.2010.11.010","article-title":"Maxillary, mandibular, and chin advancement: Treatment planning based on airway anatomy in obstructive sleep apnea","volume":"69","author":"Schendel","year":"2011","journal-title":"J. Oral. Maxillofac. Surg."},{"doi-asserted-by":"crossref","unstructured":"Wakayama, T., Suzuki, M., and Tanuma, T. (2016). Effect of Nasal Obstruction on Continuous Positive Airway Pressure Treatment: Computational Fluid Dynamics Analyses. PLoS ONE, 11.","key":"ref_26","DOI":"10.1371\/journal.pone.0150951"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1979","DOI":"10.1016\/j.jbiomech.2013.06.016","article-title":"Planning human upper airway surgery using computational fluid dynamics","volume":"46","author":"Mylavarapu","year":"2013","journal-title":"J. Biomech."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1299","DOI":"10.2514\/3.10041","article-title":"Reassessment of the scale-determining equation for advanced turbulence models","volume":"26","author":"Wilcox","year":"1988","journal-title":"Am. Inst. Aeronaut. J."},{"key":"ref_29","first-page":"43","article-title":"Turbulent Kinetic Energy of Flow during Inhale and Exhale to Characterise the Severity of Obstructive Sleep Apnea Patient","volume":"136","author":"Faizal","year":"2023","journal-title":"Comput. Model. Eng. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1553","DOI":"10.1016\/j.jbiomech.2009.03.035","article-title":"Validation of computational fluid dynamics methodology used for human upper airway flow simulations","volume":"42","author":"Mylavarapu","year":"2009","journal-title":"J. Biomech."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2221","DOI":"10.1016\/j.jbiomech.2011.06.006","article-title":"Large eddy simulation of the pharyngeal airflow associated with obstructive sleep apnea syndrome at pre and post-surgical treatment","volume":"44","author":"Mihaescu","year":"2011","journal-title":"J. Biomech."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1007\/s11325-021-02358-4","article-title":"Combined application of pharyngeal volume and minimal cross-sectional area may be helpful in screening persons suspected of obstructive sleep apnea (OSA)","volume":"26","author":"Zhao","year":"2022","journal-title":"Sleep Breath."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"280","DOI":"10.1186\/s12931-019-1250-4","article-title":"Threshold of the upper airway cross-section for hypopnea onset during sleep and its identification under waking condition","volume":"20","author":"Lin","year":"2019","journal-title":"Respir. Res."},{"doi-asserted-by":"crossref","unstructured":"Ryu, S., Kim, J.H., Yu, H., Jung, H.D., Chang, S.W., Park, J.J., Hong, S., Cho, H.J., Choi, Y.J., and Choi, J. (2021). Diagnosis of obstructive sleep apnea with prediction of flow characteristics according to airway morphology automatically extracted from medical images: Computational fluid dynamics and artificial intelligence approach. Comput. Methods Programs Biomed., 208.","key":"ref_34","DOI":"10.1016\/j.cmpb.2021.106243"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"781","DOI":"10.1016\/j.compfluid.2006.03.001","article-title":"The computation of massively separated flows using compressible vorticity confinement methods","volume":"35","author":"Hu","year":"2006","journal-title":"Comput. Fluids"}],"container-title":["Computation"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2079-3197\/12\/1\/16\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T13:48:31Z","timestamp":1760104111000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2079-3197\/12\/1\/16"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,1,17]]},"references-count":35,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2024,1]]}},"alternative-id":["computation12010016"],"URL":"https:\/\/doi.org\/10.3390\/computation12010016","relation":{},"ISSN":["2079-3197"],"issn-type":[{"type":"electronic","value":"2079-3197"}],"subject":[],"published":{"date-parts":[[2024,1,17]]}}}