scholarly journals Analysis of conductive olfactory dysfunction using computational fluid dynamics

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262579
Author(s):  
Youji Asama ◽  
Akiko Furutani ◽  
Masato Fujioka ◽  
Hiroyuki Ozawa ◽  
Satoshi Takei ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Maximum Flow ◽  
Olfactory Dysfunction ◽  
Mouth Breathing ◽  
Respiratory Physiology ◽  
Research Assessment ◽  
Nasal Breathing ◽  
Olfactory Cleft ◽  
Scan Data

Conductive olfactory dysfunction (COD) is caused by an obstruction in the nasal cavity and is characterized by changeable olfaction. COD can occur even when the olfactory cleft is anatomically normal, and therefore, the cause in these cases remains unclear. Herein, we used computational fluid dynamics to examine olfactory cleft airflow with a retrospective cohort study utilizing the cone beam computed tomography scan data of COD patients. By measuring nasal–nasopharynx pressure at maximum flow, we established a cut-off value at which nasal breathing can be differentiated from combined mouth breathing in COD patients. We found that increased nasal resistance led to mouth breathing and that the velocity and flow rate in the olfactory cleft at maximum flow were significantly reduced in COD patients with nasal breathing only compared to healthy olfactory subjects. In addition, we performed a detailed analysis of common morphological abnormalities associated with concha bullosa. Our study provides novel insights into the causes of COD, and therefore, it has important implications for surgical planning of COD, sleep apnea research, assessment of adenoid hyperplasia in children, and sports respiratory physiology.

scholarly journals Assessment of nasal resistance using computational fluid dynamics

2016 ◽  
Vol 2 (1) ◽  
pp. 617-621 ◽  
Author(s):  
Jan Osman ◽  
Friederike Großmann ◽  
Kay Brosien ◽  
Ulrich Kertzscher ◽  
Leonid Goubergrits ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gold Standard ◽  
Objective Assessment ◽  
Nasal Resistance ◽  
Nasal Breathing ◽  
Current Gold Standard ◽  
Flow Parameters

AbstractAnterior rhinomanometry is the current gold standard for the objective assessment of nasal breathing by determining the nasal resistance. However, computational fluid dynamics would allow spatially and temporally well- resolved investigation of additional flow parameters. In this study, measured values of nasal resistance are compared with measured values. An unclear discrepancy between the two methods was found, suggesting further investigation.

scholarly journals 3D Flow Modeling of the First Trifurcation Made in Nepal

1970 ◽  
Vol 5 ◽  
pp. 56-61 ◽  
Author(s):  
R K Malik ◽  
Paras Paudel
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vortex Formation ◽  
Maximum Flow ◽  
Flow Modeling ◽  
Zone Formation ◽  
Physical Constraints ◽  
3 Dimensional ◽  
Dimensional Flow ◽  
Computational Fluid Dynamics Cfd

The foremost objective of the study was to find out the most efficient profile of trifurcation in given constraints of pressure, velocity and layout of the overall geometry. The study was done for the 3.2 MW Madi Khola Hydropower Project of Gandaki Hydropower Development Co. Pvt. Ltd. The 3 Dimensional Flow modeling of the trifurcation was based on the application of Computational Fluid Dynamics (CFD).The loss in the Trifurcation greatly depends upon its geometrical configuration. The research started with a general profi le and the flow pattern generated inside it was studied with the help of 3 Dimensional Flow modeling. The extent of vortex zone formation inside the trifurcation indicates the loss inside trifurcation. The profile of the trifurcation was hence changed to reduce the vortex formation as far as possible, till we get minimum possible loss. The profile under study should meet maximum flow efficiency under the physical constraints of fabrication. The flow efficient profile was then analyzed to capture the stress amplifi cation near junction. The reinforcing element in the form of steel T-section was added of different sectional values till the stress was within allowable limits under severe conditions.Key words: Symmetrical Trifuraction; Trifurcation; Computational fluid dynamics; Hydropower; NepalDOI: 10.3126/hn.v5i0.2493Hydro Nepal Vol. 5, July 2009 Page:56-61

An Overview of Computational Fluid Dynamics Preoperative Analysis of the Nasal Airway

2021 ◽  
Author(s):  
Rui Xavier ◽  
Dirk-Jan Menger ◽  
Henrique Cyrne de Carvalho ◽  
Jorge Spratley
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Surgical Techniques ◽  
Virtual Surgery ◽  
Nasal Airway ◽  
Cfd Analysis ◽  
Nasal Airflow ◽  
Nasal Breathing ◽  
Objective Measurements ◽  
Patient Reported

AbstractEvaluation of the nasal airway is crucial for every patient with symptoms of nasal obstruction as well as for every patient with other nasal symptoms. This assessment of the nasal airway comprises clinical examination together with imaging studies, with the correlation between findings of this evaluation and symptoms reported by the patient being based on the experience of the surgeon. Measuring nasal airway resistance or nasal airflow can provide additional data regarding the nasal airway, but the benefit of these objective measurements is limited due to their lack of correlation with patient-reported evaluation of nasal breathing. Computational fluid dynamics (CFD) has emerged as a valuable tool to assess the nasal airway, as it provides objective measurements that correlate with patient-reported evaluation of nasal breathing. CFD is able to evaluate nasal airflow and measure variables such as heat transfer or nasal wall shear stress, which seem to reflect the activity of the nasal trigeminal sensitive endings that provide sensation of nasal breathing. Furthermore, CFD has the unique capacity of making airway analysis of virtual surgery, predicting airflow changes after trial virtual modifications of the nasal airway. Thereby, CFD can assist the surgeon in deciding surgery and selecting the surgical techniques that better address the features of each specific nose. CFD has thus become a trend in nasal airflow assessment, providing reliable results that have been validated for analyzing airflow in the human nasal cavity. All these features make CFD analysis a mainstay in the armamentarium of the nasal surgeon. CFD analysis may become the gold standard for preoperative assessment of the nasal airway.

scholarly journals Impact of Neurapheresis System on Intrathecal Cerebrospinal Fluid Dynamics: A Computational Fluid Dynamics Study

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Mohammadreza Khani ◽  
Lucas R. Sass ◽  
Aaron R. McCabe ◽  
Laura M. Zitella Verbick ◽  
Shivanand P. Lad ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cerebrospinal Fluid ◽  
Removal Rate ◽  
Maximum Flow ◽  
Cfd Model ◽  
Flow Loop ◽  
Steady Streaming ◽  
Lumbar Drain ◽  
The Impact

Abstract It has been hypothesized that early and rapid filtration of blood from cerebrospinal fluid (CSF) in postsubarachnoid hemorrhage patients may reduce hospital stay and related adverse events. In this study, we formulated a subject-specific computational fluid dynamics (CFD) model to parametrically investigate the impact of a novel dual-lumen catheter-based CSF filtration system, the Neurapheresis™ system (Minnetronix Neuro, Inc., St. Paul, MN), on intrathecal CSF dynamics. The operating principle of this system is to remove CSF from one location along the spine (aspiration port), externally filter the CSF routing the retentate to a waste bag, and return permeate (uncontaminated CSF) to another location along the spine (return port). The CFD model allowed parametric simulation of how the Neurapheresis system impacts intrathecal CSF velocities and steady–steady streaming under various Neurapheresis flow settings ranging from 0.5 to 2.0 ml/min and with a constant retentate removal rate of 0.2 ml/min simulation of the Neurapheresis system were compared to a lumbar drain simulation with a typical CSF removal rate setting of 0.2 ml/min. Results showed that the Neurapheresis system at a maximum flow of 2.0 ml/min increased average steady streaming CSF velocity 2× in comparison to lumbar drain (0.190 ± 0.133 versus 0.093 ± 0.107 mm/s, respectively). This affect was localized to the region within the Neurapheresis flow loop. The mean velocities introduced by the flow loop were relatively small in comparison to normal cardiac-induced CSF velocities.

scholarly journals Impact of Middle Turbinectomy on Airflow to the Olfactory Cleft: A Computational Fluid Dynamics Study

2018 ◽  
Vol 33 (3) ◽  
pp. 263-268 ◽  
Author(s):  
Suhyla Alam ◽  
Chengyu Li ◽  
Kathryn H. Bradburn ◽  
Kai Zhao ◽  
Thomas S. Lee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Middle Turbinate ◽  
Nasal Airway ◽  
Nasal Resistance ◽  
Nasal Airflow ◽  
Phenylethyl Alcohol ◽  
Olfactory Cleft ◽  
Airflow Field ◽  
The Impact

Background The impact of middle turbinate resection (MTR) on olfaction remains a point of debate in the current literature. Few studies have objectively evaluated olfactory cleft airflow following MTR; thus, the mechanism by which MTR may impact olfaction is poorly understood. It is not known whether the postsurgical changes in airway volume, flow, and resistance increase odorant transport or disrupt the patterns of normal airflow. Computational fluid dynamics can be used to study the nasal airway and predict responses to surgical intervention. Objective To evaluate the functional impact of MTR on nasal airflow, resistance, and olfaction. Methods Five maxillofacial computed tomography scans of patients without signs of significant sinusitis or nasal polyposis were used. Control models for each patient were compared to their corresponding model after virtual total MTR. For each model, nasal airway volume, nasal resistance, and air flow rate were determined. Odorant transport of 3 different odorants in the nasal cavity was simulated based on the computed steady airflow field. Results Total airflow significantly increased following bilateral MTR in all patient models ( P < .05). Consistent with our airflow results, we found a decrease in nasal resistance following MTR. MTR significantly increased area averaged flux to the olfactory cleft when compared to controls for phenylethyl alcohol (high-sorptive odorant). Results for carvone (medium sorptive) were similarly elevated. MTR impact on limonene, a low flux odorant, was equivocal. Conclusion MTR increases nasal airflow while decreasing the nasal resistance. Overall, olfactory flux increased for high sorptive (phenylethyl alcohol) and medium sorpitve (l-carvone) odorants. However, the significant variation observed in one of our models suggests that the effects of MTR on the nasal airflow and the resultant olfaction can vary between individuals based on individual anatomic differences.

Fibrous and Spherical Particle Transport and Deposition in the Human Nasal Airway: A Computational Fluid Dynamics Model

2009 ◽  
Author(s):  
Kevin T. Shanley ◽  
Goodarz Ahmadi ◽  
Philip K. Hopke ◽  
Yung-Sung Cheng
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Particulate Matter ◽  
Particle Tracking ◽  
Full Range ◽  
Spherical Particles ◽  
Lagrangian Particle Tracking ◽  
Nasal Breathing ◽  
Lagrangian Particle

As the interface between the human respiratory system and the environment, the nose plays many vital roles. Not the least of which is filter. Resulting from numerous natural and anthropogenic processes, particulate matter becomes airborne. Should particulate matter reach the lower portions of the respiratory tract, a host of maladies may occur. In an attempt to further understand the physics behind particulate matter transitioning from the environment into humans a computational model has been developed to predict the efficiency with which human noses can remove particles before they reach the lungs. To this end computational fluid dynamics and Lagrangian particle tracking simulations have been run to gather information on the deposition behavior of both fibrous and spherical particles. MRI data was collected from the left and right passages of a 181.6 cm, 120.2 kg, human male. The two passages were constructed into separate computational volumes consisting of approximately 950,000 unstructured tetrahedral cells each. A steady laminar flow model was used to simulate the inhalation portion of a human breathing cycle. Volumetric flow rates were varied to represent the full range of human nasal breathing. General agreement was shared quantitatively and qualitatively with previously published in vitro studies on other nasal models. Lagrangian particle tracking was performed for varying sizes of fibrous and spherical particles. Deposition efficiency was shown to increase with fiber aspect ratio, particle size, and flow rate. Anatomy was also identified as effecting deposition.

scholarly journals Assessing Airflow Sensitivity to Healthy and Diseased Lung Conditions in a Computational Fluid Dynamics Model Validated In Vitro

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Bora Sul ◽  
Zachary Oppito ◽  
Shehan Jayasekera ◽  
Brian Vanger ◽  
Amy Zeller ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Computational Models ◽  
Respiratory Physiology ◽  
Chronic Obstructive ◽  
Cfd Model ◽  
Flow Rates

Computational models are useful for understanding respiratory physiology. Crucial to such models are the boundary conditions specifying the flow conditions at truncated airway branches (terminal flow rates). However, most studies make assumptions about these values, which are difficult to obtain in vivo. We developed a computational fluid dynamics (CFD) model of airflows for steady expiration to investigate how terminal flows affect airflow patterns in respiratory airways. First, we measured in vitro airflow patterns in a physical airway model, using particle image velocimetry (PIV). The measured and computed airflow patterns agreed well, validating our CFD model. Next, we used the lobar flow fractions from a healthy or chronic obstructive pulmonary disease (COPD) subject as constraints to derive different terminal flow rates (i.e., three healthy and one COPD) and computed the corresponding airflow patterns in the same geometry. To assess airflow sensitivity to the boundary conditions, we used the correlation coefficient of the shape similarity (R) and the root-mean-square of the velocity magnitude difference (Drms) between two velocity contours. Airflow patterns in the central airways were similar across healthy conditions (minimum R, 0.80) despite variations in terminal flow rates but markedly different for COPD (minimum R, 0.26; maximum Drms, ten times that of healthy cases). In contrast, those in the upper airway were similar for all cases. Our findings quantify how variability in terminal and lobar flows contributes to airflow patterns in respiratory airways. They highlight the importance of using lobar flow fractions to examine physiologically relevant airflow characteristics.

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