scholarly journals Particulate Deposition in a Patient With Tracheal Stenosis

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
S. Taherian ◽  
H. R. Rahai ◽  
J. Bonifacio ◽  
B. Z. Gomez ◽  
Thomas Waddington
Keyword(s):  
Tracheal Stenosis ◽  
Air Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Ct Images ◽  
Patient Specific ◽  
Post Intervention ◽  
Cfd Simulations ◽  
Layer Manufacturing ◽  
Computational Fluid Dynamics Cfd

The presence of obstructions such as tracheal stenosis has important effects on respiratory functions. Tracheal stenosis impacts the therapeutic efficacy of inhaled medications as a result of alterations in particle transport and deposition pattern. This study explores the effects of the presence and absence of stenosis/obstruction in the trachea on air flow characteristics and particle depositions. Computational fluid dynamics (CFD) simulations were performed on three-dimensional (3D) patient-specific models created from computed tomography (CT) images. The analyzed model was generated from a subject with tracheal stenosis and includes the airway tree up to eight generations. CT scans of expiratory and inspiratory phases were used for patient-specific boundary conditions. Pre- and post-intervention CFD simulations' comparison reveals the effect of the stenosis on the characteristics of air flow, transport, and depositions of particles with diameters of 1, 2.5, 4, 6, 8, and 10 μm. Results indicate that the existence of the stenosis inflicts a major pressure force on the flow of inhaled air, leading to an increased deposition of particles both above and below the stenosis. Comparisons of the decrease in pressure in each generation between pre- and post-tracheal stenosis intervention demonstrated a significant reduction in pressure following the stenosis, which was maintained in all downstream generations. Good agreements were found using experimental validation of CFD findings with a model of the control subject up to the third generation, constructed via additive layer manufacturing from CT images.

scholarly journals The Effects of the Presence of a Kitchen House on the Wind Flow Surrounding a Low-Rise Building

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6243
Author(s):  
Siti Noratikah Che Deraman ◽  
Saddam Hussein Abo Sabah ◽  
Shaharudin Shah Zaini ◽  
Taksiah A. Majid ◽  
Amin Al-Fakih
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Pattern ◽  
Air Flow ◽  
Flow Characteristics ◽  
Wind Flow ◽  
Cfd Simulations ◽  
The Core ◽  
Computational Fluid Dynamics Cfd ◽  
Gap Height

Most Malaysian rural houses are categorized as non-engineered buildings and vulnerable to damage during events such as windstorms due to the fact that these houses lack engineering considerations. These houses are characterized by having an attached kitchen house, and many of these houses were previously damaged by thunderstorms. The current research investigated the air flow characteristics changes surrounding these houses as a result of the presence of the kitchen. The roof pitch, position, gap height, and overhang were investigated using computational fluid dynamics (CFD) simulations. The results showed that the kitchen position at the center resulted in a slight increase in the suction on the ridge of the roof; however, it significantly altered the flow pattern in the windward and leeward directions. The results also showed that the roof overhang, roof pitch, and kitchen position contributed severely to the damage of the rural house. Moreover, the highest suction occurred at the roof ridge when the kitchen was located at the center of the rural house (Cp = −2.28). Therefore, the authors believe that it is more advantageous to have a kitchen connected to the core as it reduces the pressure on the roof of the core during thunderstorm events.

3D Numerical Simulation of the Airflow in a Pneumatic Splicer

2011 ◽  
Vol 130-134 ◽  
pp. 2345-2348
Author(s):  
Xiao Xing ◽  
Guo Ming Ye
Keyword(s):  
Numerical Simulation ◽  
High Speed ◽  
Air Flow ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Swirling Flows ◽  
Computational Results ◽  
Cfd Model ◽  
3D Numerical Simulation ◽  
Computational Fluid Dynamics Cfd

To investigate the effect of air flow in an pneumatic splicer on splicing performance, a computational fluid dynamics (CFD) model has been developed to simulate the air flow characteristics in an splicing chamber. Three-dimensional numerical simulation is conducted and standard K-ε turbulence model is used. Velocity distributions in the chamber are presented and analyzed. The computational results show that the velocities in the chamber are transonic. The air flows in the chamber are two swirling flows with opposite directions. This work also shows that CFD technique can provide a better understanding of the behavior of the high speed air flow in the air splicing chamber.

Intra-Aneurysmal Flow Complexity Quantification Using Flowlines Geometry

2013 ◽  
Author(s):  
Simona Hodis ◽  
David F. Kallmes ◽  
Dan Dragomir-Daescu
Keyword(s):  
Intracranial Aneurysms ◽  
Flow Characteristics ◽  
Adaptive Grid ◽  
Patient Specific ◽  
Adaptive Grids ◽  
Cfd Simulations ◽  
Mathematical Formula ◽  
Element Size ◽  
Computational Fluid Dynamics Cfd ◽  
Topological Characteristics

We present a quantified description of the fluid flow and a novel flowline-based meshing technique to create adaptive grids for Computational Fluid Dynamics (CFD) simulations in patient-specific intracranial aneurysms. The adaptive grid density is obtained such that it captures the fine geometrical details of the flow with high grid density, while smoother flow characteristics are calculated with a coarser grid density. The correlation between the topological characteristics of the flow and the element size of the adaptive grid results in a practical mathematical formula for calculating the element size using only one uniform base mesh and a user defined implementation in CFD post processors.

Tracheal Stenosis: A CFD Approach for Evaluation of Drug Delivery

2015 ◽  
Author(s):  
Shahab Taherian ◽  
Hamid Rahai ◽  
Bernardo Z. Gomez ◽  
Thomas Waddington ◽  
Jeremy R. Bonifacio
Keyword(s):  
Pressure Drop ◽  
Tracheal Stenosis ◽  
Particle Transport ◽  
Particle Deposition ◽  
Transport Model ◽  
Ct Images ◽  
Patient Specific ◽  
Oxygen Intake ◽  
Cfd Simulations ◽  
The Impact

The existence of obstructions such as tracheal stenosis has major impacts on respiratory functions. Therapeutic effectiveness of inhaled medications is influenced by tracheal stenosis, and particle transport and deposition pattern are modified. The majority of studies have focused on obstructions in branches of the airways, where the flow is diverted to the other branches to meet the needed oxygen intake. In this study we have investigated the effects of trachea with and without stenosis/obstruction on particle depositions and air flow in a human respiratory system. Patient specific CFD simulations were conducted; CT-scans of a patient with tracheal stenosis were used to create 3D models of bronchial tree up to 8 generations. The section of the stenosis was manually modified to create a healthy trachea. Comparisons between CFD simulations before and after intervention demonstrate the impact of the stenosis on flow characteristics and particles distribution. The numerical investigations were performed using the implicit Unsteady Reynolds-Averaged Navier-Stokes equation (U-RANS), using the commercially available software (STAR-CCM+) from CD-Adapco, along with K-ω; shear stress transport model. Two sets of CT-images of inhalation and exhalation were used for assigning Patient-specific boundary conditions at the outlets. Lagrangian Phase model was used to simulate particle transport and depositions of 10, 5 and 2.5 micron diameter particles. Results of the particle depositions for 10 micron particles highlight the difference in depositions and ultimately inhaled medications in patients with and without tracheal stenosis. Particle deposition for normal Tidal volume increased due to stenosis from 47% to 51% for 10 Micron particles and not a significant change for the 2.5 Micron particles (from 4.5% to 4.7%). Comparisons of pressure drop in each generation between patient with tracheal stenosis and the healthy lung showed significant increase in pressure drop after the stenosis, which were experienced in all generations downstream. Experimental validation of the CFD results were made with a model of healthy trachea up to 3rd generation, manufactured using Additive Layer Manufacturing (ALM) from CT-images and pressure results were compared with the corresponding CFD results. Good agreements were found.

Combining patient-specific, digital 3D models with tele-education for adolescents with CHD

2021 ◽  
pp. 1-6
Author(s):  
David Liddle ◽  
Sheri Balsara ◽  
Karin Hamann ◽  
Adam Christopher ◽  
Laura Olivieri ◽  
...  
Keyword(s):  
Medical Condition ◽  
Three Dimensional ◽  
Medical Knowledge ◽  
3D Models ◽  
Patient Specific ◽  
Coarctation Of Aorta ◽  
Education Session ◽  
Post Intervention ◽  
Cardiac Defects ◽  
Transposition Of Great Arteries

Abstract Introduction: Adolescents with CHD require transition to specialised adult-centred care. Previous studies have shown that adolescents’ knowledge of their medical condition is correlated with transition readiness. Three-dimensional printed models of CHD have been used to educate medical trainees and patients, although no studies have focused on adolescents with CHD. This study investigates the feasibility of combining patient-specific, digital 3D heart models with tele-education interventions to improve the medical knowledge of adolescents with CHD. Methods: Adolescent patients with CHD, aged between 13 and 18 years old, were enrolled and scheduled for a tele-education session. Patient-specific digital 3D heart models were created using images from clinically indicated cardiac magnetic resonance studies. The tele-education session was performed using commercially available, web-conferencing software (Zoom, Zoom Video Communications Inc.) and a customised software (Cardiac Review 3D, Indicated Inc.) incorporating an interactive display of the digital 3D heart model. Medical knowledge was assessed using pre- and post-session questionnaires that were scored by independent reviewers. Results: Twenty-two adolescents completed the study. The average age of patients was 16 years old (standard deviation 1.5 years) and 56% of patients identified as female. Patients had a variety of cardiac defects, including tetralogy of Fallot, transposition of great arteries, and coarctation of aorta. Post-intervention, adolescents’ medical knowledge of their cardiac defects and cardiac surgeries improved compared to pre-intervention (p < 0.01). Conclusions: Combining patient-specific, digital 3D heart models with tele-education sessions can improve adolescents’ medical knowledge and may assist with transition to adult-centred care.

Investigation of three-dimensional printing materials for printing aorta model replicating Type B aortic dissection

2021 ◽  
Vol 17 ◽  
Author(s):  
Chia-An Wu ◽  
Andrew Squelch ◽  
Zhonghua Sun
Keyword(s):  
3D Printing ◽  
Aortic Dissection ◽  
Three Dimensional ◽  
Ct Images ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Ct Attenuation ◽  
Significant Difference ◽  
3D Printed

Aim: To determine a printing material that has both elastic property and radiology equivalence close to real aorta for simulation of endovascular stent graft repair of aortic dissection. Background: With the rapid development of three-dimensional (3D) printing technology, a patient-specific 3D printed model is able to help surgeons to make better treatment plan for Type B aortic dissection patients. However, the radiological properties of most 3D printing materials have not been well characterized. This study aims to investigate the appropriate materials for printing human aorta with mechanical and radiological properties similar to the real aortic computed tomography (CT) attenuation. Objective: Quantitative assessment of CT attenuation of different materials used in 3D printed models of aortic dissection for developing patient-specific 3D printed aorta models to simulate type B aortic dissection. Method: A 25-mm length of aorta model was segmented from a patient’s image dataset with diagnosis of type B aortic dissection. Four different elastic commercial 3D printing materials, namely Agilus A40 and A50, Visijet CE-NT A30 and A70 were selected and printed with different hardness. Totally four models were printed out and conducted CT scanned twice on a 192-slice CT scanner using the standard aortic CT angiography protocol, with and without contrast inside the lumen.Five reference points with region of interest (ROI) of 1.77 mm2 were selected at the aortic wall and intimal flap and their Hounsfield units (HU) were measured and compared with the CT attenuation of original CT images. The comparison between the patient’s aorta and models was performed through a paired-sample t-test to determine if there is any significant difference. Result: The mean CT attenuation of aortic wall of the original CT images was 80.7 HU. Analysis of images without using contrast medium showed that the material of Agilus A50 produced the mean CT attenuation of 82.6 HU, which is similar to that of original CT images. The CT attenuation measured at images acquired with other three materials was significantly lower than that of original images (p<0.05). After adding contrast medium, Visijet CE-NT A30 had an average CT attenuation of 90.6 HU, which is close to that of the original images with statistically significant difference (p>0.05). In contrast, the CT attenuation measured at images acquired with other three materials (Agilus A40, A50 and Visiject CE-NT A70) was 129 HU, 135 HU and 129.6 HU, respectively, which is significantly higher than that of original CT images (p<0.05). Conclusion: Both Visijet CE-NT and Agilus have tensile strength and elongation close to real patient’s tissue properties producing similar CT attenuation. Visijet CE-NT A30 is considered the appropriate material for printing aorta to simulate contrast-enhanced CT imaging of type B aortic dissection. Due to lack of body phantom in the experiments, further research with simulation of realistic anatomical body environment should be conducted.

Experimental and Numerical Flow Visualization in Patient Specific Pre Operative Human Airway Geometry

2011 ◽  
Author(s):  
Mathias Vermeulen ◽  
Cedric Van Holsbeke ◽  
Tom Claessens ◽  
Jan De Backer ◽  
Peter Van Ransbeeck ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Particle Image ◽  
Patient Specific ◽  
Lung Volume Reduction ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Image Velocimetry ◽  
Specific Geometry ◽  
Computational Fluid Dynamics Cfd ◽  
Human Airways

An experimental and numerical platform was developed to investigate the fluidodynamics in human airways. A pre operative patient specific geometry was used to create an identical experimental and numerical model. The experimental results obtained from Particle Image Velocimetry (PIV) measurements were compared to Computational Fluid Dynamics (CFD) simulations under stationary and pulsatile flow regimes. Together these results constitute the first step in predicting the clinical outcome of patients after lung surgeries such as Lung Volume Reduction.

Transient CFD Visualization of Fossil Fuel Combustion Simulations

2003 ◽  
Author(s):  
Brian Dotson ◽  
Kent Eshenberg ◽  
Chris Guenther ◽  
Thomas O’Brien
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Cfd Simulation ◽  
Low Cost ◽  
Three Dimensional ◽  
Cfd Simulations ◽  
Projection System ◽  
Computational Fluid Dynamics Cfd ◽  
High Level ◽  
Wall System

The design of high-efficiency lower-emission coal-fed power plants is facilitated by the extensive use of computational fluid dynamics (CFD) simulations. This paper describes work conducted at the National Energy Technology Laboratory (NETL) and Pittsburgh Supercomputing Center (PSC) to provide an environment for the immersive three-dimensional visualization of CFD simulation results. A low-cost high-resolution projection system has been developed in the visualization lab at NETL. This multi-wall system consists of four projection screens, three of which are tiled into four quadrants. The graphics for the multi-wall system are rendered using a cluster of eight personal computers. A high-level visualization interface named Mavis has also been developed to combine the powerful 3D modules of OpenDX with methods developed at NETL for studying multiphase CFD data. With Python, a completely new OpenDX user interface was built that extends and simplifies the features of a basic graphics library.

scholarly journals Computational Evaluation of Surgical Design for Multisegmental Complex Congenital Tracheal Stenosis

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Limin Zhu ◽  
Xiaolei Gong ◽  
Jinlong Liu ◽  
Youjin Li ◽  
Yumin Zhong ◽  
...  
Keyword(s):  
Tracheal Stenosis ◽  
Computer Aided Design ◽  
Surgical Correction ◽  
Patient Specific ◽  
Congenital Tracheal Stenosis ◽  
Computational Evaluation ◽  
Life Threatening ◽  
Computational Fluid Dynamics Cfd ◽  
Aerodynamic Parameters ◽  
Aided Design

Multisegmental complex congenital tracheal stenosis (CTS) is an uncommon but potentially life-threatening malformation of the airway. Staged surgery is indicated for the complex pathophysiology of the abnormal trachea. Surgical intervention to fix the stenotic segments may result in different postoperative outcomes. However, only few studies reported the design of surgical correction for multisegmental CTS. We used computer-aided design (CAD) to simulate surgical correction under different schemes to develop a patient-specific tracheal model with two segmental stenoses. Computational fluid dynamics (CFD) was used to compare the outcomes of different designs. Aerodynamic parameters of the trachea were evaluated. An obvious interaction was found between the two segments of stenosis in different surgical designs. The surgical corrective order of stenotic segments greatly affected the aerodynamic parameters and turbulence flows downstream of tracheal stenosis and upstream of the bronchus. Patient-specific studies using CAD and CFD minimize the risk of staged surgical correction and facilitate quantitative evaluation of surgical design for multiple segments of complex CTS.

scholarly journals A Comparative Study on the Performance of a Horizontal Axis Ocean Current Turbine Considering Deflector and Operating Depths

2020 ◽  
Vol 12 (8) ◽  
pp. 3333
Author(s):  
Nauman Riyaz Maldar ◽  
Cheng Yee Ng ◽  
Lee Woen Ean ◽  
Elif Oguz ◽  
Ahmad Fitriadhy ◽  
...  
Keyword(s):  
Fluid Pressure ◽  
Three Dimensional ◽  
Horizontal Axis ◽  
Ocean Current ◽  
Power Coefficient ◽  
Cfd Simulations ◽  
Torque Coefficient ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
Current Turbine

Several different designs and prototypes of ocean current turbines have been tested over recent years. For every design test, emphasis is given to achieving an optimum power output from the flow. In this study, the performance of a Horizontal Axis Ocean Current Turbine (HAOCT) has been investigated using three-dimensional Computational Fluid Dynamics (CFD) simulations for three cases, namely, (1) a turbine without a deflector, (2) a turbine with a deflector, and (3) a turbine with a deflector operating at a higher fluid depth. The turbine design was modeled in DesignModeler software and simulations were carried out in commercial CFD software Flow-3D. The Torque Coefficient (Cm) and Power Coefficient (Cp) for the turbine have been investigated for a certain range of Tip-Speed Ratios (TSRs) in a flow velocity of 0.7 m/s. Furthermore, comparisons have been made to demonstrate the effect of the deflector on the performance of the turbine and the influence of a higher fluid pressure on the same. The results from the simulations indicate that the higher value of Cp was achieved for Case 2 as compared to the other two cases. The findings from the study indicate that the use of the deflector enhances the performance of the turbine. Furthermore, a higher fluid pressure acting on the turbine has a significant effect on its performance.

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