Effects of septal perforation on nasal airflow: computer simulation study

2009 ◽  
Vol 124 (1) ◽  
pp. 48-54 ◽  
Author(s):  
H P Lee ◽  
R R Garlapati ◽  
V F H Chong ◽  
D Y Wang
Keyword(s):  
Computer Simulation ◽  
Flow Rate ◽  
Cross Flow ◽  
Computer Simulation Model ◽  
Nasal Airflow ◽  
Septal Perforation ◽  
Lower Flow ◽  
Nasal Septal Perforation ◽  
Septal Perforations ◽  
Lower Flow Rate

AbstractBackground:Nasal septal perforation is a structural or anatomical defect in the septum. The present study focused on the effects of septal perforation on nasal airflow and nasal patency, investigated using a computer simulation model.Methods:The effect of nasal septal perforation size on nasal airflow pattern was analysed using computer-generated, three-dimensional nasal models reconstructed using data from magnetic resonance imaging scans of a healthy human subject. Computer-based simulations using computational fluid dynamics were then conducted to determine nasal airflow patterns.Results:The maximum velocity and wall shear stress were found always to occur in the downstream region of the septal perforation, and could potentially cause bleeding in that region, as previously reported. During the breathing process, there was flow exchange and flow reversal through the septal perforation, from the higher flow rate to the lower flow rate nostril side, especially for moderate and larger sized perforations.Conclusion:In the breathing process of patients with septal perforations, there is airflow exchange from the higher flow rate to the lower flow rate nostril side, especially for moderate and large sized perforations. For relatively small septal perforations, the amount of cross-flow is negligible. This cross-flow may cause the whistling sound typically experienced by patients.

Impingement of liquid jets at atmospheric and elevated pressures: an observational study using paired water jets or water and methylcyclohexane jets

2010 ◽  
Vol 466 (2124) ◽  
pp. 3501-3526 ◽  
Author(s):  
Naohiro Yasuda ◽  
Koji Yamamura ◽  
Yasuhiko H. Mori
Keyword(s):  
Flow Rate ◽  
Jet Impingement ◽  
Normal Pressure ◽  
Liquid Jets ◽  
Immiscible Liquids ◽  
Lower Flow ◽  
Elevated Pressures ◽  
System Pressure ◽  
Sheet Breakup ◽  
Lower Flow Rate

We have observed the impingement of two cylindrical liquid jets of either the same liquid, water, or two mutually immiscible liquids, water and methylcyclohexane (MCH), in either air under normal pressure (0.101 MPa) or nitrogen gas under elevated pressures up to 4.0 MPa. The flow rates of the two jets were adjusted such that they had equal axial momentum. Irrespective of the system pressure, we distinguished two characteristic regimes: the lower flow-rate regime, in which the jet impingement formed a regularly shaped planar sheet, and a higher flow-rate regime, in which a wrinkled sheet repeated azimuthal breakup. The transition from the former to the latter regime occurred at a lower flow rate for the water–MCH impingement than for the water–water impingement. An increase in the system pressure tended to shrink the liquid sheets, to promote the transition to the sheet-breakup regime and to intensify the liquid atomization. The formation of water–MCH compound droplets by the water–MCH impingement was confirmed visually.

Study on the effect of pore-scale heterogeneity and flow rate during repetitive two-phase fluid flow in microfluidic porous media

2021 ◽  
pp. petgeo2020-062
Author(s):  
Jingtao Zhang ◽  
Haipeng Zhang ◽  
Donghee Lee ◽  
Sangjin Ryu ◽  
Seunghee Kim
Keyword(s):  
Porous Media ◽  
Fluid Flow ◽  
Flow Rate ◽  
Sweep Efficiency ◽  
Residual Saturation ◽  
Flow Rates ◽  
Content Type ◽  
Lower Flow ◽  
Supplementary Material ◽  
Lower Flow Rate

Various energy recovery, storage, conversion, and environmental operations may involve repetitive fluid injection and, thus, cyclic drainage-imbibition processes. We conducted an experimental study for which polydimethylsiloxane (PDMS)-based micromodels were fabricated with three different levels of pore-space heterogeneity (coefficient of variation, where COV = 0, 0.25, and 0.5) to represent consolidated and/or partially consolidated sandstones. A total of ten injection-withdrawal cycles were applied to each micromodel at two different flow rates (0.01 and 0.1 mL/min). The experimental results were analyzed in terms of flow morphology, sweep efficiency, residual saturation, the connection of fluids, and the pressure gradient. The pattern of the invasion and displacement of nonwetting fluid converged more readily in the homogeneous model (COV = 0) as the repetitive drainage-imbibition process continued. The overall sweep efficiency converged between 0.4 and 0.6 at all tested flow rates, regardless of different flow rates and COV in this study. In contrast, the effective sweep efficiency was observed to increase with higher COV at the lower flow rate, while that trend became the opposite at the higher flow rate. Similarly, the residual saturation of the nonwetting fluid was largest at COV = 0 for the lower flow rate, but it was the opposite for the higher flow rate case. However, the Minkowski functionals for the boundary length and connectedness of the nonwetting fluid remained quite constant during repetitive fluid flow. Implications of the study results for porous media-compressed air energy storage (PM-CAES) are discussed as a complementary analysis at the end of this manuscript.Supplementary material: Figures S1 and S2 https://doi.org/10.6084/m9.figshare.c.5276814.Thematic collection: This article is part of the Energy Geoscience Series collection available at: https://www.lyellcollection.org/cc/energy-geoscience-series

Asymptomatic Nasal Septal Perforations in Systemic Lupus Erythematosus

1980 ◽  
Vol 89 (1) ◽  
pp. 78-80 ◽  
Author(s):  
David Reiter ◽  
Allen R. Myers
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Lupus Erythematosus ◽  
Common Phenomenon ◽  
Septal Perforation ◽  
Systemic Lupus ◽  
Clinical Correlates ◽  
Nasal Septal Perforation ◽  
Diagnostic Criterion ◽  
Septal Perforations

Nasal septal perforation has been considered a diagnostic criterion for systemic lupus erythematosus since 1971. However, little has been published in the otorhinolaryngologic literature regarding this lesion. We report six patients having asymptomatic anteroinferior nasal septal perforations and symptomatic lupus. No obvious clinical correlates were found. We support the hypothesis that nasal septal perforation in systemic lupus erythematosus is a common phenomenon, and attribute its infrequent detection to the asymptomatic nature of the lesion in this setting.

Repair of Nasal Septal Perforation

1997 ◽  
Vol 11 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Mohammed Yousef-Mian
Keyword(s):  
Success Rate ◽  
Double Layer ◽  
The Other ◽  
Septal Perforation ◽  
Current Analysis ◽  
Operative Techniques ◽  
Nasal Septal Perforation ◽  
Novel Method ◽  
Incomplete Closure ◽  
Septal Perforations

The management of nasal septal perforation remains unsatisfactory. Various operative techniques have been described, with modest success. A novel method for repair of septal perforations up to 2.6 cm in diameter was investigated. A double layer closure of nasal septal perforation was designed, one with the cartilage and the other by a flap based on the anterior septal branches of the sphenopalatine artery. Fourteen patients have been operated upon. The current analysis reveals a success rate of 13 patients (93%) who had complete closure and one patient (7%) with incomplete closure. The operative techniques and results are reported here.

Nasal Septal Perforation and Carotid Cavernous Aneurysm: Unusual Manifestations of Systemic Lupus Erythematosus

1996 ◽  
Vol 115 (1) ◽  
pp. 163-166 ◽  
Author(s):  
Don N. Lerner
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Central Nervous System ◽  
Nervous System ◽  
Lupus Erythematosus ◽  
Septal Perforation ◽  
Vascular Disorder ◽  
Cell Nuclei ◽  
Systemic Lupus ◽  
Nasal Septal Perforation ◽  
Septal Perforations

Systemic lupus erythematosus (SLE) is a multisystem collagen vascular disorder defined by its clinical features and the presence of antibodies in the blood directed against one or more cell nuclei components. Typically, SLE affects the head and neck in the form of cutaneous malar erythema and oropharyngeal mucosal ulcerations. The uncommon findings of nasal septal perforations and restrictive central nervous system (CNS) aneurysmal formation as initial manifestations of SLE are detailed in this case report.

Modified tragal cartilage – temporoparietal and deep temporal fascia sandwich graft technique for repair of nasal septal perforations

1997 ◽  
Vol 111 (5) ◽  
pp. 435-437 ◽  
Author(s):  
A. Hussain ◽  
P. Murthy
Keyword(s):  
Operative Technique ◽  
Observation Time ◽  
Septal Perforation ◽  
Sandwich Technique ◽  
Temporal Fascia ◽  
Nasal Septal Perforation ◽  
Septal Perforations

AbstractFifteen cases of nasal septal perforation were repaired with a tragal cartilage–temporoparietal and deep temporal fascia sandwich technique using a modification of the approach previously described (Hussain and Kay, 1992). Successful closure was achieved in 14 patients (100 per cent) after an observation time of up to two years. The operative technique and advantages of the modified approach are described.

scholarly journals Significant Improvements in Pyranometer Nighttime Offsets Using High-Flow DC Ventilation

2017 ◽  
Vol 34 (6) ◽  
pp. 1323-1332 ◽  
Author(s):  
Joseph J. Michalsky ◽  
Mark Kutchenreiter ◽  
Charles N. Long
Keyword(s):  
Flow Rate ◽  
Direct Current ◽  
Alternating Current ◽  
High Flow ◽  
Future Research ◽  
Lower Flow ◽  
Black And White ◽  
Ventilation Strategies ◽  
Future Work ◽  
Lower Flow Rate

AbstractVentilators are used to keep the domes of pyranometers clean and dry, but they affect the nighttime offset as well. This paper examines different ventilation strategies. For the several commercial single-black-detector pyranometers with ventilators examined here, high-flow-rate [50 cubic feet per minute (CFM) and higher] 12-VDC (where VDC refers to voltage direct current) fans lower the offsets, lower the scatter, and improve the predictability of the offsets during the night compared with lower-flow-rate (35 CFM) 120-VAC (where VAC refers to voltage alternating current) fans operated in the same ventilator housings. Black-and-white pyranometers sometimes show improvement with DC ventilation, but in some cases DC ventilation makes the offsets slightly worse. Since the offsets for these black-and-white pyranometers are always small, usually no more than 1 W m−2, whether AC or DC ventilated, changing their ventilation to higher CFM DC ventilation is not imperative. Future work should include all major manufacturers of pyranometers and unventilated and ventilated pyranometers. An important outcome of future research will be to clarify under what circumstances nighttime data can be used to predict daytime offsets.

Fluctuation of Inducer Recirculation Stemming From Diffuser Stall in Centrifugal Turbomachinery Near Surge Condition

2020 ◽  
Author(s):  
Kazuhiro Tsukamoto ◽  
Chisachi Kato
Keyword(s):  
Flow Rate ◽  
Pressure Rise ◽  
Time History ◽  
Rotating Stall ◽  
Centrifugal Impeller ◽  
Performance Curve ◽  
Positive Slope ◽  
Lower Flow ◽  
Suction Pipe ◽  
Lower Flow Rate

Abstract This work investigates the unsteady fluctuation of inducer recirculation stemming from the diffuser stall that occurs near the surge condition. Experiments and unsteady numerical simulation were utilized for the investigation. Inducer recirculation is known to occur near the surge occurrence flow rate, where the flow rate has a positive slope of the performance curve and the recirculation extends to the upstream of the impeller inlet when decreasing the flow rate more. However, few papers have investigated the unsteady phenomenon of the recirculation, even though the surge is what causes it. Clarifying the recirculation phenomenon is essential in terms of expanding the operation range to the lower flow rate for centrifugal turbomachinery. This was our motivation for investigating the unsteady oscillation phenomenon of the inducer recirculation. We investigated a single-stage centrifugal blower with the maximum pressure rise ratio of 1.2 and focused on the flow rates near surge occurrence. The blower was equipped with an open type centrifugal impeller, a vane-less diffuser, and a scroll casing. The blower performance and pressure time-history data were obtained by experiments. Unsteady simulations using large eddy simulation (LES) were conducted to investigate the flow field in the blower for each flow rate. The obtained performance curve showed that the positive slope of the pressure rise at the lower flow rate was due to the impeller stall and that the inducer recirculation extending upstream of the suction pipe near the slope of the curve was flat. LES analysis revealed that this inducer recirculation had two typical fluctuation peaks, one at 20% of the rotation frequency and the other at 95%. We also found that the stall cell at the impeller inlet propagated in the circumferential direction and swirled at almost the same frequency as the impeller rotation. In addition, the fluctuation at the diffuser derived from the diffuser rotating stall propagated to the suction pipe.

scholarly journals A NOTE ON STEADY FLOW INTO A SUBMERGED POINT SINK

2014 ◽  
Vol 56 (2) ◽  
pp. 150-159 ◽  
Author(s):  
G. C. HOCKING ◽  
L. K. FORBES ◽  
T. E. STOKES
Keyword(s):  
Free Surface ◽  
Steady Flow ◽  
Flow Rate ◽  
Axisymmetric Flow ◽  
Inviscid Fluid ◽  
Past Work ◽  
Lower Flow ◽  
Steady Solutions ◽  
Lower Flow Rate

AbstractThe steady, axisymmetric flow induced by a point sink (or source) submerged in an unbounded inviscid fluid is computed. The resulting deformation of the free surface is obtained, and a limit of steady solutions is found that is quite different to those obtained in past work. More accurate solutions indicate that the old limiting flow rate was too high and, in fact, the breakdown of steady solutions at a lower flow rate is characterized by the appearance of spurious wavelets at the free surface.

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