Numerical simulation of humidification and heating during inspiration within an adult nose

2012 ◽  
Vol 50 (2) ◽  
pp. 157-164
Author(s):  
F. Sommer ◽  
R. Kroger ◽  
J. Lindemann
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Middle Turbinate ◽  
Multislice Ct ◽  
Respiratory Cycle ◽  
In Vivo Measurements ◽  
Airflow Distribution ◽  
The Impact ◽  
Human Nose

Background: The temperature of inhaled air is highly relevant for the humidification process. Narrow anatomical conditions limit possibilities for in vivo measurements. Numerical simulations offer a great potential to examine the function of the human nose. Objective: In the present study, the nasal humidification of inhaled air was simulated simultaneously with temperature distribution during a respiratory cycle. Methods: A realistic nose model based on a multislice CT scan was created. The simulation was performed by the Software Fluent(r). Boundary conditions were based on previous in vivo measurements. Inhaled air had a temperature of 20(deg)C and relative humidity of 30%. The wall temperature was assumed to be variable from 34(deg)C to 30(deg)C with constant humidity saturation of 100% during the respiratory cycle. Results: A substantial increase in temperature and humidity can be observed after passing the nasal valve area. Areas with high speed air flow, e.g. the space around the turbinates, show an intensive humidification and heating potential. Inspired air reaches 95% humidity and 28(deg)C within the nasopharynx. Conclusion: The human nose features an enormous humidification and heating capability. Warming and humidification are dependent on each other and show a similar spacial pattern. Concerning the climatisation function, the middle turbinate is of high importance. In contrast to in vivo measurements, numerical simulations can explore the impact of airflow distribution on nasal air conditioning. They are an effective method to investigate nasal pathologies and impacts of surgical procedures.

Dose reduction in multislice CT by means of bismuth shields: results of in vivo measurements and computed evaluation

2009 ◽  
Vol 115 (1) ◽  
pp. 152-169 ◽  
Author(s):  
P. Catuzzo ◽  
S. Aimonetto ◽  
G. Fanelli ◽  
P. Marchisio ◽  
T. Meloni ◽  
...  
Keyword(s):  
Dose Reduction ◽  
Multislice Ct ◽  
In Vivo Measurements

Effects of Substance P and Methacholine on Mucosal Blood Flow in the Upper Airways

1995 ◽  
Vol 9 (6) ◽  
pp. 335-348 ◽  
Author(s):  
Thomas Runer ◽  
Sven Lindberg ◽  
Ulf Mercke ◽  
Peter Olsson
Keyword(s):  
Blood Flow ◽  
Substance P ◽  
Maxillary Sinus ◽  
Middle Turbinate ◽  
Mucosal Blood Flow ◽  
Laser Doppler ◽  
Upper Airways ◽  
Doppler Probe ◽  
Human Nose

The aims of the present investigation were to examine the in vivo effects of substance P (SP) and methacholine on blood flow measured by laser Doppler technique in the maxillary sinus of the rabbit and in the human nasal mucosa. In the rabbit, the test substances were administered by intra-arterial catheter, and the laser Doppler probe was inserted into the maxillary sinus through a trepanation in the anterior wall. In the human nose, the laser Doppler probe was directed toward the nasal septum at the level of the anterior margin of the middle turbinate, and the test substances were administered as aerosols into the ipsilateral nostril. In the rabbit maxillary sinus, both SP and methacholine increased the blood flow, the maximum increases obtained being 13.5 ± 3.1% and 39.0 ± 5.6% after challenges with SP at 0.1 μg/kg and methacholine at 0.5 μg/kg, respectively. The rabbits displayed a decrease in blood flow after challenges at higher dosages of both SP and methacholine, accompanied by a simultaneous fall in systemic blood pressure. Atropine given IV five minutes before methacholine abolished the effects of this compound in the rabbit. The blood flow in the human nose was unaffected by saline controls, whereas it was increased both by SP and by methacholine, the increases being 34.9 ± 6.0% after challenges with SP 1.0 nmol and 119.2 ± 15.1% after challenges with methacholine 5.0 μmol. According to acoustic rhinometry, neither SP nor methacholine had, at the doses used, any effect on human nasal patency. Pretreatment with lidocaine hydrochloride spray into the human nose did not affect the increase in nasal blood flow induced by SP, but abolished the methacholine-evoked blood flow increase. Pretreatment with ipratropium bromide spray into the human nose abolished the increase in blood flow induced by methacholine. The results of the present study indicate that blood flow in the upper airways of humans and rabbits may increase due to release of SP or acetylcholine in vivo, an event that occurs after exposure to airway irritants. The vasodilation in the human nose produced by acetylcholine may be due to a neurogenic reflex, in contrast to the effect of SP.

scholarly journals Biomechanical Models of the Hip – a Validation Study Based on 10 CT-Datasets

10.29007/rxxb ◽  
2018 ◽  
Author(s):  
Jörg Eschweiler ◽  
Malte Asseln ◽  
Philipp Damm ◽  
Maximilian C.M Fischer ◽  
Klaus Radermacher
Keyword(s):  
Hip Joint ◽  
Long Term Results ◽  
Patient Specific ◽  
Anatomical Landmarks ◽  
Joint Mechanics ◽  
X Ray ◽  
Biomechanical Models ◽  
In Vivo Measurements ◽  
The Impact

Consideration of the pre- and post-operative magnitude of the hip joint force R and its orientation Ɵ is of major importance for satisfactory long-term results in total hip arthroplasty. R and Ɵ can be computed by using biomechanical models with adapted geometrical/ anthropometrical parameters taken from clinical X-ray images. The objective of this study was to evaluate the models of Pauwels and Debrunner based on digital reconstructed-radiographs (central projection) from 10 CT-datasets of patients treated with telemetric hip-implants by a comparison to corresponding in-vivo measurements.R and Ɵ were computed for 10 patients with patient-specific geometric/anthropometric parameters. The model adaption was based on 28 anatomical landmarks. The root-mean-square-error of R is smaller for Debrunner (0.59/vs./0.66), and for Ɵ it is smaller for Pauwels’ (4.47/vs./7.78).Mathematical models provide potentially valuable information regarding hip joint mechanics. Regarding R, in all of the 10 patients the predictions of Pauwels’ model are consistently higher than the in-vivo measurements. Debrunner computed R in 8 cases higher and in 2 cases lower than the corresponding in-vivo forces. Pauwels’ and Debrunner showed similar tendencies: in 8 cases an overestimation of R and in 2 cases contrary results. Regarding Ɵ we found that in 5 cases the predictions of Pauwels’ are consistently higher than the in-vivo measurements and also contrary to Debrunner.As previous studies showed, an unambiguous identification of most landmarks in a 2D X-ray image is difficult. The impact of the pelvic tilt on the computational result was not considered in our study. Further investigation of this aspect is part of our ongoing work.

scholarly journals In-Vivo Measurements of Ischiofemoral Distance in Recreationally Active Subjects During Dynamic Activities: A High-Speed Dual-Fluoroscopy Study

2016 ◽  
Vol 3 (suppl_1) ◽  
Author(s):  
Penny R. Atkins ◽  
Niccolo M. Fiorentino ◽  
Sara J. Fauver ◽  
Stephen Kenji Aoki ◽  
Christopher L. Peters ◽  
...  
Keyword(s):  
High Speed ◽  
In Vivo Measurements

scholarly journals Investigation of Shock Initiation in Covered Charges under Shock Wave and Fragment Impacts

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xingwang Chen ◽  
Jinxiang Wang ◽  
Kui Tang ◽  
Hongfei Wang ◽  
Yuanbo Li
Keyword(s):  
Shock Wave ◽  
Theoretical Model ◽  
Numerical Simulations ◽  
High Speed ◽  
Least Squares Method ◽  
Strong Shock ◽  
Protective Function ◽  
Shock Initiation ◽  
Metal Plates ◽  
The Impact

In the current work, a series of step-by-step research methods have been applied to address the damaging effects of near-field strong shock waves and high-speed fragments on covered charge. In the first step, the defects of covered plates due to high-speed fragments were simplified to penetrated notches, and then, these notches were used to evaluate the impact of shock wave loads on charges covered with metal plates. In the next step, we developed a theoretical model to take into account the shock initiation of charges covered with defected metal plates. Explosive initiation standards coupled with shock wave evolution characteristics were applied to specify the crucial conditions of explosive detonation. Finite element program, for instance, was applied for the simulation of shock initiation processes in pressed charges (when TNT was covered with a steel plate containing a penetrated notch), and then, numerical simulations were validated by experimental findings. Finally, the results obtained from the numerical simulations and theoretical model were applied to evaluate the impacts of shock wave intensity, the thickness of covered metal plate, and the geometrical features of penetrated notch on pressed charge shock initiation. The least squares method was applied to determine critical initiation criteria (n and K). Theoretical calculation results were found to be highly consistent with those obtained from numerical simulations, indicating that covered metal plates significantly contributed to charge protection. The results also revealed that notches could undermine the protective function of covered plates and the size and shape of notch significantly affected charge critical detonation distance. Critical detonation distances of noncontact explosions were found to be 25 and 81 mm for a 3 mm thick pressed TNT in the presence and absence of 45# steel-covered plate, respectively. According to the results, increase in the diameter of covered plates containing a cylindrical notch increased pressed TNT critical detonation distance. When dealing with a covered plate containing a normally reflected frustum notch, however, we figured out that any increase in normal reflection slope could decrease pressed TNT critical detonation distance.

scholarly journals Early-time jet formation in liquid–liquid impact problems: theory and simulations

2018 ◽  
Vol 856 ◽  
pp. 764-796 ◽  
Author(s):  
R. Cimpeanu ◽  
M. R. Moore
Keyword(s):  
Numerical Simulations ◽  
High Speed ◽  
Early Stage ◽  
Early Time ◽  
Leading Order ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Jet Velocity ◽  
The Impact ◽  
Wagner Theory

We perform a thorough qualitative and quantitative comparison of theoretical predictions and direct numerical simulations for the two-dimensional, vertical impact of two droplets of the same fluid. In particular, we show that the theoretical predictions for the location and velocity of the jet root are excellent in the early stages of the impact, while the predicted jet velocity and thickness profiles are also in good agreement with the computations before the jet begins to bend. By neglecting the role of the surrounding gas both before and after impact, we are able to use Wagner theory to describe the early-time structure of the impact. We derive the model for general droplet velocities and radii, which encompasses a wide range of impact scenarios from the symmetric impact of identical drops to liquid drops impacting a deep pool. The leading-order solution is sufficient to predict the curve along which the root of the high-speed jet travels. After moving into a frame fixed in this curve, we are able to derive the zero-gravity shallow-water equations governing the leading-order thickness and velocity of the jet. Our numerical simulations are performed in the open-source software Gerris, which allows for the level of local grid refinement necessary for a problem with such a wide variety of length scales. The numerical simulations incorporate more of the physics of the problem, in particular the surrounding gas, the fluid viscosities, gravity and surface tension. We compare the computed and predicted solutions for a range of droplet radii and velocities, finding excellent agreement in the early stage. In light of these successful comparisons, we discuss the tangible benefits of using Wagner theory to confidently track properties such as the jet-root location, jet thickness and jet velocity in future studies of splash jet/ejecta evolution.

In Vivo Measurements of Thermal Load During Ablation in High-speed Laser Corneal Refractive Surgery

2011 ◽  
Vol 28 (1) ◽  
pp. 53-58 ◽  
Author(s):  
Diego de Ortueta ◽  
Thomas Magnago ◽  
Nico Triefenbach ◽  
Samuel Arba Mosquera ◽  
Udo Sauer ◽  
...  
Keyword(s):  
Thermal Load ◽  
High Speed ◽  
Refractive Surgery ◽  
In Vivo Measurements ◽  
Corneal Refractive Surgery

Erosion and accretion by cratering impacts on rocky and icy bodies: Formulation of scaling relations for high-speed ejecta

2021 ◽  
Author(s):  
Hidenori Genda ◽  
Ryuki Hyodo
Keyword(s):  
Point Source ◽  
Numerical Simulations ◽  
High Speed ◽  
Scaling Law ◽  
Large Body ◽  
Target Material ◽  
Target Surface ◽  
Impact Angle ◽  
Material Strength ◽  
The Impact

<p>Numerous small bodies inevitably lead to cratering impacts on large planetary bodies during planet formation and evolution. As a consequence of these small impacts, a fraction of the target material escapes from the gravity of the large body, and a fraction of the impactor material accretes onto the target surface, depending on the impact velocities and angles. Here, we study the mass of the high-speed ejecta that escapes from the target gravity by cratering impacts when material strength is neglected. We perform a large number of cratering impact simulations onto a planar rocky and icy targets using the smoothed particle hydrodynamics method. We show that the escape mass of the target material obtained from our numerical simulations agrees with the prediction of a scaling law under a point-source assumption when <em>v</em><sub>imp</sub> > ~ 10 <em>v</em><sub>esc</sub>, where <em>v</em><sub>imp</sub> is the impact velocity and <em>v</em><sub>esc</sub> is the escape velocity of the target. However, we find that the point-source scaling law overestimates the escape mass up to a factor of ~ 70, depending on the impact angle, when <em>v</em><sub>imp</sub> < ~ 10 <em>v</em><sub>esc</sub> (Figure 1). Using data obtained from numerical simulations, we derive a new scaling law for the escape mass of the target material

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