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Journal articles on the topic 'Airflow patterns'

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Published: 4 June 2021

Last updated: 10 February 2022

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1

Hutchison, A. A., J. A. Wozniak, H. G. Choi, M. Conlon, R. A. Otto, R. M. Abrams, and P. C. Kosch. "Laryngeal and diaphragmatic muscle activities and airflow patterns after birth in premature lambs." Journal of Applied Physiology 75, no. 1 (July 1, 1993): 121–31. http://dx.doi.org/10.1152/jappl.1993.75.1.121.

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The nature and control of early neonatal respiratory patterns were determined in 10 premature, asphyxiated lambs. Severe retardation of early expiratory airflow (braking) characterized an initial pattern (A), but was absent in a final one (B). During a transition pattern (pattern T), pattern A and B airflow types occurred. Close temporal relationships between the airflow patterns and posterior cricoarytenoid (PCA), thyroarytenoid (TA), and diaphragm (D) integrated muscle activities were demonstrated quantitatively. Specifically, in pattern A, the duration of braked expiratory airflow was related to the durations of TA burst activity and the absence of PCA burst activity (r2 = 0.99). In pattern A, pH, but not arterial PCO2 or arterial PO2, differed from that in patterns T and B [7.01 +/- 0.14 (A), 7.11 +/- 0.12 (T), 7.19 +/- 0.08 (B) (P < 0.03)]. Within-breath airflow and respiratory muscle activity relationships and differences in neural and mechanical respiratory timing intervals between patterns suggested that neural feedback was important in the control of central pattern generation. Thus activities of PCA, TA, and D shape the early neonatal airflow patterns and are influenced mainly by neuromechanical, and not chemical, feedback.

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2

Huang, Hanyao, Heng Yin, Yang Wang, Nan Chen, Dantong Huang, Xiangyou Luo, Xing Yin, Qian Zheng, Bing Shi, and Jingtao Li. "Computational Fluid Dynamic Analysis of Different Velopharyngeal Closure Patterns." Annals of Otology, Rhinology & Laryngology 129, no. 2 (September 30, 2019): 157–63. http://dx.doi.org/10.1177/0003489419879176.

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Objective: Velopharyngeal (VP) closure has high impact on the quality of life, especially in patients with cleft palate. For better understanding the VP closure, it is important to understand the airflow dynamics of different closure patterns, including circular, coronal, sagittal, and circular with a Passavant’s ridge. The purpose of this study was to demonstrate the airflow characteristics of different velopharyngeal closure patterns. Methods: Sixteen adults with no notable upper airway abnormality who needed multislice spiral computed tomography scans as part of their clinical care. Airways were reconstructed. A cylinder and a cuboid were used to replace the VP port in three models of VP port patterns. Flow simulations were carried using computational fluid dynamics. Airflow pressures in the VP orifice, oral cavity and nasal cavity, as well as airflow velocity through the velopharyngeal orifice, were calculated. Results: The airflow dynamics at the velopharynx were different among different velopharyngeal patterns as the area of the velopharyngeal port increased from 0 to 25 mm2. The orifice areas of different closure conditions in four velopharyngeal closure patterns were significantly different. The maximal orifice area for adequate velopharyngeal closure was 7.57 mm2 in the coronal pattern and 6.21 mm2 in the sagittal pattern. Conclusions: Airflow dynamics of the velopharynx were correlated to the velopharyngeal closure patterns. Different closure patterns had different largest permitted orifice areas for getting the appropriate oral pressures for normal speech.

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3

Alipour, Fariborz, and Douglas Montequin. "Airflow patterns in hemilarynx models." Journal of the Acoustical Society of America 108, no. 5 (November 2000): 2530. http://dx.doi.org/10.1121/1.4743365.

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4

Li, Hancao, and Wassim M. Haddad. "Optimal Determination of Respiratory Airflow Patterns Using a Nonlinear Multicompartment Model for a Lung Mechanics System." Computational and Mathematical Methods in Medicine 2012 (2012): 1–11. http://dx.doi.org/10.1155/2012/165946.

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We develop optimal respiratory airflow patterns using a nonlinear multicompartment model for a lung mechanics system. Specifically, we use classical calculus of variations minimization techniques to derive an optimal airflow pattern for inspiratory and expiratory breathing cycles. The physiological interpretation of the optimality criteria used involves the minimization of work of breathing and lung volume acceleration for the inspiratory phase, and the minimization of the elastic potential energy and rapid airflow rate changes for the expiratory phase. Finally, we numerically integrate the resulting nonlinear two-point boundary value problems to determine the optimal airflow patterns over the inspiratory and expiratory breathing cycles.

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5

Mennella, Julie A., and Gary K. Beauchamp. "Developmental Changes in Nasal Airflow Patterns." Acta Oto-Laryngologica 112, no. 6 (January 1992): 1025–31. http://dx.doi.org/10.3109/00016489209137505.

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6

Xing, Jin Cheng, Yun Ping Wang, Ji Hong Ling, Yong Pan Li, and Yun Zhe Ji. "The Effect of Airflow Patterns on the Purification Efficiency of the Operating Room." Advanced Materials Research 340 (September 2011): 444–50. http://dx.doi.org/10.4028/www.scientific.net/amr.340.444.

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There are two unidirectional patterns in OR: horizontal unidirectional airflow and vertical unidirectional airflow. In order to compare their purification effect, computational fluid dynamics (CFD) was applied to simulate the two airflow patterns and the results are as following: Firstly, the number of the particles that hit the surgical key areas in the case of the horizontal unidirectional airflow is obviously less than that in the case of the vertical unidirectional airflow in the condition of the same air volume. Secondly, the number of the particles that hit the incisions will be satisfactory at a velocity of 0.25~0.3m/s in the case of the vertical unidirectional airflow while a velocity of 0.28~0.37m∕s in the case of the horizontal unidirectional airflow. Thirdly, the number of indoor residual particles in the case of the horizontal airflow is obviously less than that in the case of the vertical airflow in the case of the same air volume.

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7

Wang, Huan, Maohui Luo, Guijin Wang, and Xianting Li. "Airflow pattern induced by ceiling fan under different rotation speeds and blowing directions." Indoor and Built Environment 29, no. 10 (November 25, 2019): 1425–40. http://dx.doi.org/10.1177/1420326x19890054.

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Ceiling fans have been widely used as effective cooling and air mixing method for building environment conditioning. Understanding its airflow characteristics can be helpful to utilize ceiling fan or integrate it with background air conditioning system. However, the airflow induced by ceiling fan has different flow patterns under different rotating speeds and blowing directions. To date, it is still challenging to capture those complicated airflow fields in room scale. In this study, the airflow pattern induced by a ceiling fan was measured with a new technology, quad-view colour sequence particle streak velocimetry. A series of isothermal experiments were conducted under five rotation speed levels with downward and upward blowing directions in a room-size (4 m × 2.5 m × 3 m) chamber. Based on comprehensive three-dimensional three-component vector measurement results, the average velocity, turbulence intensity and vorticity on the middle section were calculated and used to analyse airflow patterns induced by ceiling fan. The results show that the blowing direction of the fan determines the indoor airflow pattern. When blowing downward, the flow will cause high diversion between jet core under the fan blades and surrounding region. While for upward blowing, the air speed in lower part of the room is much lower but pretty uniform. The detailed measured airflow fields can serve as reference for ceiling fan design and operation.

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8

Walker, Ian J., and William G. Nickling. "Dynamics of secondary airflow and sediment transport over and in the lee of transverse dunes." Progress in Physical Geography: Earth and Environment 26, no. 1 (March 2002): 47–75. http://dx.doi.org/10.1191/0309133302pp325ra.

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Recent research literature on secondary airflow and sediment transport patterns over flow-transverse dunes is reviewed. Various issues surrounding the behaviour, modelling and sedimentological implications of near-surface airflow dynamics over dunes are discussed, including: the Law of the Wall; the Jackson and Hunt airflow model; the effects of streamline compression, acceleration and curvature on stoss slope shear stress; and, in particular, recent efforts to characterize secondary lee-side airflow patterns. A revised conceptual model of lee-side airflow is presented and areas for further research are identified regarding the implications of such patterns for dune sedimentary dynamics, morphology, and migration.

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9

Khoukhi, Maatouk. "Investigation of Airflow Patterns Inside Tall Building." Recent Patents on Engineering 3, no. 1 (January 1, 2009): 65–70. http://dx.doi.org/10.2174/187221209787259901.

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10

J. E. Chapman, R. Vance Moray, H. A. Cloud, and J. L. Nieber. "Airflow Patterns in Flat Storage Aeration Systems." Transactions of the ASAE 32, no. 4 (1989): 1368–73. http://dx.doi.org/10.13031/2013.31158.

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11

Mayes, Julian C. "Regional airflow patterns in the British Isles." International Journal of Climatology 11, no. 5 (July 6, 2007): 473–91. http://dx.doi.org/10.1002/joc.3370110502.

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12

Hornung, D. E., D. A. Leopold, S. L. Youngentob, P. R. Sheehe, G. M. Gagne, F. D. Thomas, and M. M. Mozell. "Airflow Patterns in a Human Nasal Model." Archives of Otolaryngology - Head and Neck Surgery 113, no. 2 (February 1, 1987): 169–72. http://dx.doi.org/10.1001/archotol.1987.01860020061013.

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13

Wooldridge, G., R. Musselman, B. Connell, and D. Fox. "Airflow patterns in a small subalpine basin." Theoretical and Applied Climatology 45, no. 1 (1992): 37–41. http://dx.doi.org/10.1007/bf00865991.

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14

Joe, P. I., T. R. Nichols, and C. L. Crozier. "Airflow patterns in two mesoscale convective systems." Atmospheric Research 25, no. 1-3 (February 1990): 167–94. http://dx.doi.org/10.1016/0169-8095(90)90011-z.

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15

Williams, M., and R. Eccles. "A model for the central control of airflow patterns within the human nasal cycle." Journal of Laryngology & Otology 130, no. 1 (October 20, 2015): 82–88. http://dx.doi.org/10.1017/s0022215115002881.

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AbstractBackground:The nasal cycle exhibits mainly reciprocal changes in nasal airflow that may be controlled from centres in the hypothalamus and brainstem. This study aims to gather new knowledge about the nasal cycle to help develop a control model.Method:Right and left nasal airflow was measured in healthy human subjects by rhinomanometry. This was performed over 7-hour periods on 2 study days separated by approximately 1 week. The correlation coefficient for nasal airflow was calculated for day 1 and day 2.Results:Thirty subjects (mean age, 22.7 years) completed the study. The correlation coefficient for nasal airflow varied between r = 0.97 with in-phase changes in airflow and r = −0.89 with reciprocal changes in airflow. The majority of r values were negative, indicating reciprocal changes in airflow (50 out of 60). There was a tendency for r values to become more negative between day 1 and day 2 (p < 0.001).Conclusion:A control model involving a hypothalamic centre and two brainstem half centres is proposed to explain both the in-phase and reciprocal changes in airflow associated with the nasal cycle.

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16

Shea, S. A., T. Pham Dinh, R. D. Hamilton, A. Guz, and G. Benchetrit. "Breathing Patterns of Monozygous Twins during Behavioural Tasks." Acta geneticae medicae et gemellologiae: twin research 42, no. 2 (April 1993): 171–84. http://dx.doi.org/10.1017/s0001566000002063.

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AbstractTo better understand behavioural and genetic influences upon breathing, the breathing patterns of 8 pairs of monozygous (MZ) twins were measured under 4 behavioural conditions; relaxed without standardisation; eyes closed; eyes open; and reading. Breathing was quantified by inspiratory and expiratory durations (TI, TE), tidal volume (VT) and derived variables. Airflow shape was normalised and quantified using 8 dimensions. Reading caused breathing to increase by > 500 ml/min compared to the other four conditions. Differences in breathing between combinations of two conditions were compared by testing whether the differences within an individual were smaller than the differences between random pairs of individuals from the same 16 subjects. For almost all respiratory variables, and whatever the behavioural condition, there were highly significant similarities within an individual (p < 0.00025 on 32/80 comparisons). Under each condition, the differences within MZ twin-pairs were compared to the differences within random-pairs from the same subject population. There were highly significant similarities within twin-pairs for the airflow shape across all conditions. However, TI, TE and VT failed to consistently show significant similarities within twin pairs. Hence, an individual's airflow shape appears to be a fundamental characteristic which is conserved when behavioural condition and level of ventilation changes. Further, MZ twins have similar airflow shapes – whatever the behavioural situation. Hence, behavioural influences upon airflow shape act upon monozygous twin pairs in similar ways, or such influences were negligible under the conditions of the present study.

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17

Li, Fu Sheng, Dong Sun, Xin Xi Xu, Xiao Hui Liu, and Shu Lin Tan. "Large Eddy Simulation of Airflow Structural Characteristics in Real Human Mouth-Throat Model." Applied Mechanics and Materials 184-185 (June 2012): 292–95. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.292.

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Accurate simulation for airflow structural characteristics in the human mouth-throat model plays an important role in analyzing the filter effect of pharynx and larynx and the diffusion, transition and deposition patterns of aerosol in human upper respiratory tract. Large eddy simulation was used to simulate the airflow movement in human mouth-throat model in the conditions of the cyclic respiratory pattern, and the airflow structural characteristic in mouth-throat model was discussed. The results show that two velocity growth points generated in pharyngeal and laryngeal region; the airflow separates in region near the pharynx and the separation zone appears near the anterior wall of pharynx; A turbulence jet appears in the glottal region and the airflow; the high velocity zone is created in pharynx and larynx, and the phenomenon of airflow separation appeared in the pharynx. In the process of cyclic exhalation, the phenomenon of airflow separation didn’t appear in the pharynx and larynx.

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18

Fujimoto, Masako, and Seiya Funatsu. "Airflow patterns of voiced geminate stops in Japanese." Acoustical Science and Technology 39, no. 2 (2018): 66–74. http://dx.doi.org/10.1250/ast.39.66.

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19

Maddieson, Ian, and Rachid Saghrouni. "Airflow and duration patterns in Tunisian Arabic fricatives." Journal of the Acoustical Society of America 129, no. 4 (April 2011): 2451. http://dx.doi.org/10.1121/1.3588046.

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20

P. S. Plue and W. K. Bilanski. "Airflow and Temperature Patterns Through Large Round Bales." Applied Engineering in Agriculture 7, no. 5 (1991): 525–29. http://dx.doi.org/10.13031/2013.26262.

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21

Weir, M. J. C. "AIRFLOW PATTERNS FROM PHOTOGRAMMETRIC MEASUREMENTS OF WINDBLOWN TIMBER." Photogrammetric Record 7, no. 42 (August 26, 2006): 731–36. http://dx.doi.org/10.1111/j.1477-9730.1973.tb01213.x.

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22

Renaudo, Carlos Alberto, Diego Esteban Bertin, and Verónica Bucalá. "Design Impact on Airflow Patterns in Fluidization Units." Chemical Engineering & Technology 42, no. 11 (August 20, 2019): 2365–75. http://dx.doi.org/10.1002/ceat.201800580.

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23

Saha, Chayan Kumer, Qianying Yi, David Janke, Sabrina Hempel, Barbara Amon, and Thomas Amon. "Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study." Applied Sciences 10, no. 17 (September 1, 2020): 6054. http://dx.doi.org/10.3390/app10176054.

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Airflow inside naturally ventilated dairy (NVD) buildings is highly variable and difficult to understand due to the lack of precious measuring techniques with the existing methods. Computational fluid dynamics (CFD) was applied to investigate the effect of different seasonal opening combinations of an NVD building on airflow patterns and airflow rate inside the NVD building as an alternative to full scale and scale model experiments. ANSYS 2019R2 was used for creating model geometry, meshing, and simulation. Eight ventilation opening combinations and 10 different reference air velocities were used for the series of simulation. The data measured in a large boundary layer wind tunnel using a 1:100 scale model of the NVD building was used for CFD model validation. The results show that CFD using standard k-ε turbulence model was capable of simulating airflow in and outside of the NVD building. Airflow patterns were different for different opening scenarios at the same external wind speed, which may affect cow comfort and gaseous emissions. Guiding inlet air by controlling openings may ensure animal comfort and minimize emissions. Non-isothermal and transient simulations of NVD buildings should be carried out for better understanding of airflow patterns.

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24

Ban Yu-Lin, Andrea. "Defining the Prevalence and Predictors of Restrictive and Obstructive Airway Pattern in a Non-Selected Malaysian Population." Medicine & Health 15, no. 2 (December 31, 2020): 140–52. http://dx.doi.org/10.17576/mh.2020.1502.14.

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The incidence of chronic obstructive pulmonary disease (COPD) in Malaysia appear to be increasing. To date, there are no local studies describing restrictive and obstructive airflow limitation patterns using spirometry. We conducted a crosssectional study to determine the prevalence and predictors of airflow limitation symptoms by screening for COPD symptoms with the COPD Population Screener (COPD-PS) questionnaire and determined the airflow limitation using the new hand-held device, AirSmart®. We recruited 265 subjects. Eleven percent had restrictive pattern and 16% had obstructive pattern. Twenty percent of subjects had COPD-PS score of more than five. In the obstructive pattern group, 74% were active or ex-smokers (p=0.03, p<0.01), whilst those with restrictive pattern were more likely to be heavier with a body mass index (BMI) of more than 23 (OR 2.52, 95% CI: 1.02-5.62) (p<0.01). There was a negative correlation between forced vital capacity and BMI (r=-0.5813, p<0.001). We found a high prevalence restrictive pattern of airflow limitation using the new AirSmart® Spirometer. There appeared to be a large proportion of undiagnosed obstructive airway diseases and higher BMI could be the causes of limitation of airflow in our subjects.

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25

Dotevall, Hans, Hasse Ejnell, and Björn Bake. "Nasal Airflow Patterns during the Velopharyngeal Closing Phase in Speech in Children with and without Cleft Palate." Cleft Palate-Craniofacial Journal 38, no. 4 (July 2001): 358–73. http://dx.doi.org/10.1597/1545-1569_2001_038_0358_napdtv_2.0.co_2.

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Objectives: (1) To study the nasal airflow patterns during the velopharyngeal closing phase in speech produced by children with and without cleft palate. (2) To compare the nasal airflow patterns in bilabial, dental, and velar articulation in these children. Design: Prospective, cross-sectional study of a consecutive series of children with cleft palate referred for routine speech evaluation and controls. Setting: Sahlgrenska University Hospital, Göteborg, Sweden. Participants: Seventeen children with cleft lip and palate or cleft palate only and 22 controls aged 7 and 10 years. Method: Nasal airflow was transduced with a pneumotachograph attached to a nose mask and registered together with the acoustic speech signal. Sentences containing nasal-to-stop combinations in bilabial, dental, and velar articulatory positions were used. Main Outcomes Measures: The duration from peak to 5% nasal airflow, the maximum flow declination rate, and the nasal airflow at selected points in time during the transition from nasal-to-stop consonants. Results: In the cleft palate group, duration from peak to 5% nasal airflow was clearly longer than among the controls (p < .0001). The declination of airflow was slower (p < .006) and the rate of nasal airflow at the release of the stop consonant was higher (p < .004) in the cleft palate group. Differences between bilabial versus dental and velar articulation were found in the control group. Conclusion: Studies of the temporal and dynamic characteristics of the nasal airflow variations during speech appear potentially useful for the assessment of velopharyngeal function.

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26

Mogensen, Ida, Tiago Jacinto, Kjell Alving, João A. Fonseca, Christer Janson, and Andrei Malinovschi. "Inflammatory patterns in fixed airflow obstruction are dependent on the presence of asthma." PLOS ONE 15, no. 12 (December 3, 2020): e0243109. http://dx.doi.org/10.1371/journal.pone.0243109.

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Rationale Fixed airflow obstruction (FAO) can complicate asthma. Inflammation is a proposed underlying mechanism. Objective Our aim in this cross-sectional investigation was to evaluate the blood leucocyte pattern and level of exhaled nitric oxide in asthmatics and non-asthmatics with or without FAO. Methods A total of 11,579 individuals aged ≥20 years from the US National Health and Nutrition Examination Survey were included. They were grouped as: controls without asthma and FAO (n = 9,935), asthmatics without FAO (n = 674), asthmatics with FAO (n = 180) and non-asthmatics with FAO (n = 790). FAO was defined as post-bronchodilator FEV1/FVC < lower limit of normal. Exhaled nitric oxide ≥ 25ppb, blood eosinophil levels ≥300 cells/μL, and blood neutrophil levels ≥5100 cells/μL were defined as elevated. Stratified analyses for smoking and smoking history were performed. Results Elevated blood eosinophil levels were more common in all groups compared to the controls, with the highest prevalence in the group with asthma and fixed airflow obstruction (p<0.01). In a multiple logistic regression model adjusted for potential confounders including smoking, the asthma groups had significantly higher odds ratios for elevated B-Eos levels compared to the control group (odds ratio 1.4, (confidence interval: 1.1–1.7) for the asthma group without fixed airflow obstruction and 2.5 (1.4–4.2) for the asthma group with fixed airflow obstruction). The group with fixed airflow obstruction without asthma had higher odds ratio for elevated blood neutrophil levels compared to the controls: 1.4 (1.1–1.8). Smoking and a history of smoking were associated to elevated B-Neu levels. Conclusion Fixed airflow obstruction in asthma was associated with elevated blood eosinophil levels, whereas fixed airflow obstruction without asthma was associated with elevated blood neutrophil levels.

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27

Eisele, J. H., B. Wuyam, G. Savourey, J. Eterradossi, J. H. Bittel, and G. Benchetrit. "Individuality of breathing patterns during hypoxia and exercise." Journal of Applied Physiology 72, no. 6 (June 1, 1992): 2446–53. http://dx.doi.org/10.1152/jappl.1992.72.6.2446.

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Breathing was recorded via a pulsed ultrasonic flowmeter in 11 healthy subjects, at rest and during steady-state exercise (at 50% of their maximal O2 consumption) at both sea level (200 m) and simulated altitude (4,500 m in a hypobaric chamber). The pattern of breathing was quantified breath by breath in terms of classical respiratory variables (tidal volume and inspiratory and expiratory times), and the shape of the entire airflow profile was quantified by harmonic analysis. Statistical tests were used to compare the within-individual with the between-individual variations. In comparing the sea level vs. altitude rest (16% increase in ventilation) and sea level vs. altitude exercise (40% increase in ventilation) airflow profiles, we found a significantly greater resemblance within the individual than between individuals. Comparisons of sea level rest and exercise (295% increase in ventilation) and altitude rest and exercise (375% increase in ventilation) revealed no similarity within individuals. Despite airflow profile changes between rest and exercise, it is still possible to attest to a diversity of flow profile between individuals during exercise. Hypoxia at rest or during exercise does not alter the phenomenon of the individuality of breathing patterns.

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28

Craven, Brent A., Eric G. Paterson, and Gary S. Settles. "The fluid dynamics of canine olfaction: unique nasal airflow patterns as an explanation of macrosmia." Journal of The Royal Society Interface 7, no. 47 (December 9, 2009): 933–43. http://dx.doi.org/10.1098/rsif.2009.0490.

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The canine nasal cavity contains hundreds of millions of sensory neurons, located in the olfactory epithelium that lines convoluted nasal turbinates recessed in the rear of the nose. Traditional explanations for canine olfactory acuity, which include large sensory organ size and receptor gene repertoire, overlook the fluid dynamics of odorant transport during sniffing. But odorant transport to the sensory part of the nose is the first critical step in olfaction. Here we report new experimental data on canine sniffing and demonstrate allometric scaling of sniff frequency, inspiratory airflow rate and tidal volume with body mass. Next, a computational fluid dynamics simulation of airflow in an anatomically accurate three-dimensional model of the canine nasal cavity, reconstructed from high-resolution magnetic resonance imaging scans, reveals that, during sniffing, spatially separate odour samples are acquired by each nostril that may be used for bilateral stimulus intensity comparison and odour source localization. Inside the nose, the computation shows that a unique nasal airflow pattern develops during sniffing, which is optimized for odorant transport to the olfactory part of the nose. These results contrast sharply with nasal airflow in the human. We propose that mammalian olfactory function and acuity may largely depend on odorant transport by nasal airflow patterns resulting from either the presence of a highly developed olfactory recess (in macrosmats such as the canine) or the lack of one (in microsmats including humans).

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29

Chen, Bohao, Gustine Liu, Felix Shardonofsky, Maria Dowell, Oren Lakser, Richard W. Mitchell, Jeffrey J. Fredberg, Lawrence H. Pinto, and Julian Solway. "Tidal breathing pattern differentially antagonizes bronchoconstriction in C57BL/6J vs. A/J mice." Journal of Applied Physiology 101, no. 1 (July 2006): 249–55. http://dx.doi.org/10.1152/japplphysiol.01010.2004.

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There is abundant evidence that tidal breathing, and especially tidal breathing at elevated minute ventilation, antagonizes the development and persistence of airflow obstruction during bronchoconstrictor stimulation in normal animals and people. Here, we studied the antiobstructive effect of different tidal breathing patterns in C57Bl/6J and A/J mice during bronchoconstriction induced by continuous or bolus infusion of methacholine. Anesthetized, paralyzed mice were mechanically ventilated at 1,500 ml·kg−1·min−1, using each of three breathing patterns: 5 ml/kg, 300 breath/min; 10 ml/kg, 150 breath/min; or 20 ml/kg, 75 breath/min. Changing from 10 ml/kg, 150 breath/min to 20 ml/kg, 75 breath/min, breathing functionally antagonized bronchoconstriction, reducing the level of airflow obstruction induced by methacholine infusion or boluses equivalently in both strains. In marked contrast, changing from 10 ml/kg, 150 breath/min to 5 ml/kg, 300 breath/min, breathing substantially exacerbated methacholine-induced airflow obstruction in A/J mice, whereas it had no significant effect in C57Bl/6J mice. Our results therefore demonstrate that 1) even at moderate, fixed minute ventilation, the precise breathing pattern can influence the degree of airflow obstruction substantially, and 2) the influence of breathing pattern on bronchoconstriction differs considerably between genetically diverse inbred mouse strains. These findings imply that differences in antiobstructive effects of breathing can contribute to differences in apparent airway constrictor responsiveness. Much attention has been placed on dysregulation of contractile function of airway smooth muscle in human disease. We suggest that important pathophysiology might also be found in impairment of the functional antagonist effect of tidal breathing on airflow obstruction.

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30

Mader, T. L., J. M. Dahlquist, and J. B. Gaughan. "Wind protection effects and airflow patterns in outside feedlots." Journal of Animal Science 75, no. 1 (1997): 26. http://dx.doi.org/10.2527/1997.75126x.

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31

Powell, Nelson B., Mihai Mihaescu, Goutham Mylavarapu, Edward M. Weaver, Christian Guilleminault, and Ephraim Gutmark. "Patterns in pharyngeal airflow associated with sleep-disordered breathing." Sleep Medicine 12, no. 10 (December 2011): 966–74. http://dx.doi.org/10.1016/j.sleep.2011.08.004.

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32

Tapsoba, Mitoubkieta, Jean Moureh, and Denis Flick. "Airflow patterns in an enclosure loaded with slotted pallets." International Journal of Refrigeration 29, no. 6 (September 2006): 899–910. http://dx.doi.org/10.1016/j.ijrefrig.2006.01.011.

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33

Zhu, Jian Hua, Heow Pueh Lee, Kian Meng Lim, Shu Jin Lee, Lynette Teo Li San, and De Yun Wang. "Inspirational airflow patterns in deviated noses: a numerical study." Computer Methods in Biomechanics and Biomedical Engineering 16, no. 12 (December 2013): 1298–306. http://dx.doi.org/10.1080/10255842.2012.670850.

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34

Schachner, Emma R., Robert L. Cieri, James P. Butler, and C. G. Farmer. "Unidirectional pulmonary airflow patterns in the savannah monitor lizard." Nature 506, no. 7488 (December 11, 2013): 367–70. http://dx.doi.org/10.1038/nature12871.

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LEOPOLD, DONALD A., DAVID E. HORNUNG, ROBERT L. RICHARDSON, PAUL F. KENT, MAXWELL M. MOZELL, and STEVEN L. YOUNGENTOB. "A Changing Density Technique to Measure Nasal Airflow Patterns." Annals of the New York Academy of Sciences 510, no. 1 Olfaction and (November 1987): 451–53. http://dx.doi.org/10.1111/j.1749-6632.1987.tb43587.x.

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Williams, E. M., R. G. Madgwick, and M. J. Morris. "Tidal expired airflow patterns in adults with airway obstruction." European Respiratory Journal 12, no. 5 (November 1, 1998): 1118–23. http://dx.doi.org/10.1183/09031936.98.12051118.

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Wang, Zhongwei, Jian Zhang, and Ting Ren. "Numerical investigations of airflow patterns on a longwall face." International Journal of Oil, Gas and Coal Technology 24, no. 3 (2020): 321. http://dx.doi.org/10.1504/ijogct.2020.10028648.

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Wang, Zhongwei, Ting Ren, and Jian Zhang. "Numerical investigations of airflow patterns on a longwall face." International Journal of Oil, Gas and Coal Technology 24, no. 3 (2020): 321. http://dx.doi.org/10.1504/ijogct.2020.107551.

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Tapsoba, Mitoubkieta, Jean Moureh, and Denis Flick. "Airflow patterns inside slotted obstacles in a ventilated enclosure." Computers & Fluids 36, no. 5 (June 2007): 935–48. http://dx.doi.org/10.1016/j.compfluid.2006.04.002.

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Batchelder, Keith A., Paul D. Mannheimer, Roger S. Mecca, and Joseph M. Ojile. "Pulse oximetry saturation patterns detect repetitive reductions in airflow." Journal of Clinical Monitoring and Computing 25, no. 6 (November 20, 2011): 411–18. http://dx.doi.org/10.1007/s10877-011-9321-1.

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Jiang, Jiaxin, Xiang Wang, Wenwang Li, Juan Liu, Yifang Liu, and Gaofeng Zheng. "Electrohydrodynamic Direct-Writing Micropatterns with Assisted Airflow." Micromachines 9, no. 9 (September 11, 2018): 456. http://dx.doi.org/10.3390/mi9090456.

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Electrohydrodynamic direct-writing (EDW) is a developing technology for high-resolution printing. How to decrease the line width and improve the deposition accuracy of direct-written patterns has been the key to the promotion for the further application of EDW. In this paper, an airflow-assisted spinneret for electrohydrodynamic direct-writing was designed. An assisted laminar airflow was introduced to the EDW process, which provided an additional stretching and constraining force on the jet to reduce the surrounding interferences and enhance jet stability. The flow field and the electric field around the spinneret were simulated to direct the structure design of the airflow-assisted spinneret. Then, a series of experiments were conducted, and the results verified the spinneret design and demonstrated a stable ejection of jet in the EDW process. With assisted airflow, the uniformity of printed patterns and the deposition position accuracy of a charged jet can be improved. Complex patterns with positioning errors of less than 5% have been printed and characterized, which provide an effective way to promote the integration of micro/nanosystems.

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Dotevall, Hans, Anette Lohmander-Agerskov, Hasse Ejnell, and Björn Bake. "Perceptual Evaluation of Speech and Velopharyngeal Function in Children with and without Cleft Palate and the Relationship to Nasal Airflow Patterns." Cleft Palate-Craniofacial Journal 39, no. 4 (July 2002): 409–24. http://dx.doi.org/10.1597/1545-1569_2002_039_0409_peosav_2.0.co_2.

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Objectives The aim was to study the relationship between perceptual evaluation of speech variables related to velopharyngeal function and the pattern of nasal airflow during the velopharyngeal closing phase in speech in children with and without cleft palate. Participants Fourteen children with cleft lip and palate or cleft palate only and 15 controls aged 7 and 10 years. All were native Swedish speakers. Method Three experienced listeners performed a blinded perceptual speech evaluation. Nasal airflow was transduced with a pneumotachograph attached to a nasal mask. The duration from peak to 5% nasal airflow, maximum flow declination rate, and nasal airflow at selected points in time during the transition from nasal to stop consonants in bilabial and velar articulatory positions in sentences were estimated. The analysis was focused on the perceptual ratings of “velopharyngeal function” and “hypernasality.” Results A strong association was found between ratings of “velopharyngeal function” and “hypernasality” and the pattern of nasal airflow during the bilabial nasal-to-stop combination /mp/. Both the sensitivity and specificity were 1.00 for the bilabial temporal airflow measure in relation to ratings of “velopharyngeal function.” The nasal airflow rate during /p/ in /mp/ had a sensitivity of 1.00 and specificity of 0.92 to 0.96 in relation to ratings of “hypernasality.” Conclusion Assessment of the nasal airflow dynamics during the velopharyngeal closing phase in speech presents quantitative, objective data that appear to distinguish between perceptually normal and deviant velopharyngeal function with high sensitivity and specificity.

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Wang, Huan, Guijin Wang, and Xianting Li. "Implementation of demand-oriented ventilation with adjustable fan network." Indoor and Built Environment 29, no. 4 (January 7, 2020): 621–35. http://dx.doi.org/10.1177/1420326x19897114.

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Airflow patterns are essential for heating, ventilation and air conditioning (HVAC) systems. Traditional HVAC systems are predesigned and operated using a fixed airflow pattern. However, the indoor occupancy and heat source always vary and therefore, the fixed flow pattern cannot efficiently maintain the required indoor environment conditions. In this study, a novel Adjustable Fan Network (AFN) for improving airflow pattern manoeuvrability is proposed. It integrates multiple small and adjustable axial fans into an AFN, enabling it to change the airflow pattern based on the actual demand with only one set of equipment. Further, the outflow characteristics of two types of axial fans were measured using a quad-view colour sequence particle streak velocimetry (CSPSV) in a test chamber. The ventilation system was then designed based on typical scenarios. Finally, the performance of the AFN was evaluated under different scenarios using a quad-view CSPSV. Based on the results, it was evident that the AFN can provide a better direct supply of air to the occupied zone under different scenarios. With the growing demand for personal thermal comfort and energy-saving in HVAC systems, the novel AFN system has a great potential to be a highly controllable terminal for demand-oriented ventilation.

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Huang, Hanyao, Xu Cheng, Yang Wang, Dantong Huang, Yuhao Wei, Heng Yin, Bing Shi, and Jingtao Li. "Analysis of Velopharyngeal Functions Using Computational Fluid Dynamics Simulations." Annals of Otology, Rhinology & Laryngology 128, no. 8 (April 8, 2019): 742–48. http://dx.doi.org/10.1177/0003489419842217.

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Objectives: Competent velopharyngeal (VP) function is the basis for normal speech. Understanding how VP structure influences the airflow during speech details is essential to the surgical improvement of pharyngoplasty. In this study, we aimed to illuminate the airflow features corresponding to various VP closure states using computed dynamic simulations. Methods: Three-dimensional models of the upper airways were established based on computed tomography of 8 volunteers. The velopharyngeal port was simulated by a cylinder. Computational fluid dynamics simulations were applied to illustrate the correlation between the VP port size and the airflow parameters, including the flow velocity, pressure in the velopharyngeal port, as well as the pressure in oral and nasal cavity. Results: The airflow dynamics at the velopharynx were maintained in the same velopharyngeal pattern as the area of the velopharyngeal port increased from 0 to 25 mm2. A total of 5 airflow patterns with distinct features were captured, corresponding to adequate closure, adequate/borderline closure (Class I and II), borderline/inadequate closure, and inadequate closure. The maximal orifice area that could be tolerated for adequate VP closure was determined to be 2.01 mm2. Conclusion: Different VP functions are of characteristic airflow dynamic features. Computational fluid dynamic simulation is of application potential in individualized VP surgery planning.

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Davis, Pamela J., Daniel R. Boone, Paul Darveniza, Raymond L. Carroll, and Gordon A. Harrison. "Adductor Spastic Dysphonia: Heterogeneity of Physiologic and Phonatory Characteristics." Annals of Otology, Rhinology & Laryngology 97, no. 2 (March 1988): 179–85. http://dx.doi.org/10.1177/000348948809700216.

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Physiologic and phonatory characteristics of 23 subjects with adductor spastic dysphonia were studied, including examination of the laryngeal appearance by fiberoptic nasoendoscopy, neurologic examination, and measurement of phonatory airflow and speaking fundamental frequency. These characteristics displayed considerable heterogeneity among the subjects investigated. Three patterns of laryngeal appearance during phonation were observed: Vocal fold adduction, associated ventricular fold constriction, and approximation of the laryngeal inlet. Eight of 13 subjects demonstrated some neurologic abnormality. For the majority of subjects, the airflow demonstrated marked variability during sustained phonation; for different subjects, this variability was observed to be associated with either an oscillatory or irregular airflow pattern. The modal speaking fundamental frequency for the women and men with adductor spastic dysphonia was not significantly different from that for age- and sex-matched controls.

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Guan, X., R. A. Segal, M. Shearer, and T. B. Martonen. "Mathematical Model of Airflow in the Lungs of Children II: Effects of Ventilatory Parameters." Journal of Theoretical Medicine 3, no. 1 (2000): 51–62. http://dx.doi.org/10.1080/10273660008833064.

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In an effort to develop more effective aerosol therapy procedures, we examined airflow patterns in the lung of a child (age four years). In particular, we were concerned with how ventilatory parameters (i.e., breathing rate and tidal volume) affected the patterns of airflow around tumors. To conduct the study, a computational fluid dynamics package, FIDAP was used to define a model lung. The results of simulations show the extent to which changing ventilatory parameters can affect flow patterns in the neighborhood of the tumors as well as drug distribution throughout the lung.

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Jia, F., M. K. Patel, E. R. Galea, A. Grandison, and J. Ewer. "CFD fire simulation of the Swissair flight 111 in-flight fire – Part 1: Prediction of the pre-fire air flow within the cockpit and surrounding areas." Aeronautical Journal 110, no. 1103 (January 2006): 41–52. http://dx.doi.org/10.1017/s0001924000004358.

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Abstract The SMARTFIRE computational fluid dynamics (CFD) software was used to predict the ‘possible’ behaviour of airflow as well as the spread of fire and smoke within a Swissair configured McDonnell Douglas MD-11 commercial transport aircraft. This work was undertaken by the Fire Safety Engineering Group (FSEG) of the University of Greenwich as part of Transportation Safety Board (TSB) of Canada, Fire & Explosion Group’s investigation into the in-flight fire occurrence onboard Swissair Flight 111 (SR111): TSB Report Number A98H0003. The main aims of the CFD analysis were to develop a better understanding of the possible effects, or lack thereof, of numerous variables relating to the in-flight fire. This assisted investigators in assessing possible fire dynamics for cause and origin determination. In Part 1, the numerical analyses to pre-fire airflow patterns within the cockpit and its vicinity are presented. The pre-fire simulations serve two ends. One is to provide insight into the flow patterns within the cockpit and its vicinity and further supportive numerical evidence for the airflow flight test observations. The other is to provide plausible initial flow conditions for fire simulations. In this paper, some flow patterns at a number of primary locations within the cockpit and its vicinity are highlighted and the predicted flow patterns are compared with the findings from the airflow flight tests. The predicted patterns are found to be in good qualitative agreement with the experimental test findings.

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Eiting, Thomas P., J. Blair Perot, and Elizabeth R. Dumont. "How much does nasal cavity morphology matter? Patterns and rates of olfactory airflow in phyllostomid bats." Proceedings of the Royal Society B: Biological Sciences 282, no. 1800 (February 7, 2015): 20142161. http://dx.doi.org/10.1098/rspb.2014.2161.

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The morphology of the nasal cavity in mammals with a good sense of smell includes features that are thought to improve olfactory airflow, such as a dorsal conduit that delivers odours quickly to the olfactory mucosa, an enlarged olfactory recess at the back of the airway, and a clear separation of the olfactory and respiratory regions of the nose. The link between these features and having a good sense of smell has been established by functional examinations of a handful of distantly related mammalian species. In this paper, we provide the first detailed examination of olfactory airflow in a group of closely related species that nevertheless vary in their sense of smell. We study six species of phyllostomid bats that have different airway morphologies and foraging ecologies, which have been linked to differences in olfactory ability or reliance. We hypothesize that differences in morphology correlate with differences in the patterns and rates of airflow, which in turn are consistent with dietary differences. To compare species, we make qualitative and quantitative comparisons of the patterns and rates of airflow through the olfactory region during both inhalation and exhalation across the six species. Contrary to our expectations, we find no clear differences among species in either the patterns of airflow through the airway or in rates of flow through the olfactory region. By and large, olfactory airflow seems to be conserved across species, suggesting that morphological differences appear to be driven by other mechanical demands on the snout, such as breathing and feeding. Olfactory ability may depend on other aspects of the system, such as the neurobiological processing of odours that work within the existing morphology imposed by other functional demands on the nasal cavity.

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Li, Zheng, Clement Kleinstreuer, and Zhe Zhang. "Simulation of airflow fields and microparticle deposition in realistic human lung airway models. Part I: Airflow patterns." European Journal of Mechanics - B/Fluids 26, no. 5 (September 2007): 632–49. http://dx.doi.org/10.1016/j.euromechflu.2007.02.003.

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Chen, Xiao Bing, Heow Pueh Lee, Vincent Fook Hin Chong, and De Yun Wang. "Aerodynamic Characteristics inside the Rhino-Sinonasal Cavity after Functional Endoscopic Sinus Surgery." American Journal of Rhinology & Allergy 25, no. 6 (November 2011): 388–92. http://dx.doi.org/10.2500/ajra.2011.25.3669.

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Background The aim of this study was to evaluate effects of functional endoscopic sinus surgery (FESS) on transient nasal aerodynamic flow patterns using computational fluid dynamics (CFD) simulations. Methods A three-dimensional model of the nasal cavity was constructed from CT scans of a patient with FESS interventions on the right side of the nasal cavity. CFD simulations were then performed for unsteady aerodynamic flow modeling inside the nasal cavity as well as the sinuses. Results Comparisons of the local velocity magnitude and streamline distributions inside the left and right nasal cavity and maxillary sinus regions were presented. Because of the FESS procedures in the right nasal cavity, existences and distributions of local circulations (vortexes) were found to be significantly different for the same nasal airflow rate but at different acceleration, deceleration, or quiet phases in the maxillary sinus region on the FESS side. Because of inertia effects, local internal airflow with circulation existences was continuous throughout the whole respiration cycle. With a larger peak inspiration flow rate, the airflow intensity inside the enlarged maxillary sinus increased significantly. Possible outcomes on functional performances of the nose were also examined and discussed. Conclusion Surgical enlargements of natural ostium of the maxillary sinus will change the aerodynamic patterns inside the main nasal cavity and maxillary sinus regions, which may affect normal nasal physiological functions. Local inertia effects play more important roles for the internal nasal airflow pattern changes and thus such conventional FESS procedures should be carefully planned.

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