CFD Simulations of Radioembolization: A Proof-of-Concept Study on the Impact of the Hepatic Artery Tree Truncation

Radioembolization (RE) is a treatment for patients with liver cancer, one of the leading cause of cancer-related deaths worldwide. RE consists of the transcatheter intraarterial infusion of radioactive microspheres, which are injected at the hepatic artery level and are transported in the bloodstream, aiming to target tumors and spare healthy liver parenchyma. In paving the way towards a computer platform that allows for a treatment planning based on computational fluid dynamics (CFD) simulations, the current simulation (model preprocess, model solving, model postprocess) times (of the order of days) make the CFD-based assessment non-viable. One of the approaches to reduce the simulation time includes the reduction in size of the simulated truncated hepatic artery. In this study, we analyze for three patient-specific hepatic arteries the impact of reducing the geometry of the hepatic artery on the simulation time. Results show that geometries can be efficiently shortened without impacting greatly on the microsphere distribution.

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Numerical and experimental analyses for the improvement of surface instant decontamination technology through biocidal agent dispersion: Potential of application during pandemic

PLoS ONE ◽

10.1371/journal.pone.0251817 ◽

2021 ◽

Vol 16 (5) ◽

pp. e0251817

Author(s):

Paulo Roberto Freitas Neves ◽

Turan Dias Oliveira ◽

Tarcísio Faustino Magalhães ◽

Paulo Roberto Santana dos Reis ◽

Luzia Aparecida Tofaneli ◽

...

Keyword(s):

Experimental Tests ◽

Cfd Simulations ◽

New Device ◽

Qualitative And Quantitative ◽

Droplet Concentration ◽

Computational Fluid Dynamics Cfd ◽

Suspended Droplet ◽

The Impact ◽

Disinfection Chamber ◽

Important Form

The transmission of SARS-CoV-2 through contact with contaminated surfaces or objects is an important form of transmissibility. Thus, in this study, we evaluated the performance of a disinfection chamber designed for instantaneous dispersion of the biocidal agent solution, in order to characterize a new device that can be used to protect individuals by reducing the transmissibility of the disease through contaminated surfaces. We proposed the necessary adjustments in the configuration to improve the dispersion on surfaces and the effectiveness of the developed equipment. Computational Fluid Dynamics (CFD) simulations of the present technology with a chamber having six nebulizer nozzles were performed and validated through qualitative and quantitative comparisons, and experimental tests were conducted using the method Water-Sensitive Paper (WSP), with an exposure to the biocidal agent for 10 and 30 s. After evaluation, a new passage procedure for the chamber with six nozzles and a new configuration of the disinfection chamber were proposed. In the chamber with six nozzles, a deficiency was identified in its central region, where the suspended droplet concentration was close to zero. However, with the new passage procedure, there was a significant increase in wettability of the surface. With the proposition of the chamber with 12 nozzles, the suspended droplet concentration in different regions increased, with an average increase of 266%. The experimental results of the new configuration proved that there was an increase in wettability at all times of exposure, and it was more significant for an exposure of 30 s. Additionally, even in different passage procedures, there were no significant differences in the results for an exposure of 10 s, thereby showing the effectiveness of the new configuration or improved spraying and wettability by the biocidal agent, as well as in minimizing the impact caused by human factor in the performance of the disinfection technology.

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

ASME 2011 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2011-53370 ◽

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.

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De-risking flight trials using airwake simulations

10.24868/issn.2515-818x.2018.039 ◽

2018 ◽

Author(s):

C M Ward

Keyword(s):

Royal Navy ◽

Exposure Limits ◽

Cfd Simulations ◽

Real Time System ◽

Flow Features ◽

Operating Limits ◽

Turbulent Airflow ◽

Computational Fluid Dynamics Cfd ◽

The Impact ◽

Rotary Wing

Air operations around naval vessels are inherently challenging and a major contributor to this is the turbulent airflow around the vessels, colloquially known as the airwake. To manage the risks associated with these unsteady airflows and to help define safe operating limits for the ship and the aircraft, the Royal Navy undertakes First of Class Flight Trials (FOCFTs). However, these trials inherently carry their own risks as well as being costly and time consuming. This paper discusses how Computational Fluid Dynamics (CFD) simulations have been used to de-risk flight trials and operations on the Queen Elizabeth Class (QEC) carriers. The simulations are shown to be in excellent agreement with full-scale LiDAR and anemometer measurements, which provides the requisite confidence to use them as a basis for de-risking. To de-risk the rotary wing FOCFTs, the turbulence approach parameter was defined as a proxy for pilot workload. It is shown that this parameter can be used to identify the wind conditions that are likely to be the most difficult for pilots, and to advise on changes to the approach paths that would reduce pilot workload. Test pilots were briefed with this airwake information prior to the FOCFTs, and the flow features identified in the CFD were found to be consistent with the pilots’ experiences. In the future this analysis could be used to reduce the time and cost associated with flight trials, manage through-life risks, and assess the impact of design decisions on the airwake during ship design. The work has also been used to de-risk F-35 trials and operations. In particular, the findings show that it may be possible to extend the operating envelope of the aircraft using a novel real-time system to predict airwake turbulence. In addition, CFD simulations were used to de-risk ondeck operations by ensuring that aircraft are within their exposure limits when tied-down. This information was used by the FOCFTs teams during rotary wing trials.

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From imaging to hemodynamics – how reconstruction kernels influence the blood flow predictions in intracranial aneurysms

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2016-0148 ◽

2016 ◽

Vol 2 (1) ◽

pp. 679-683 ◽

Cited By ~ 2

Author(s):

Sylvia Glaßer ◽

Philipp Berg ◽

Samuel Voß ◽

Steffen Serowy ◽

Gabor Janiga ◽

...

Keyword(s):

Blood Flow ◽

Intracranial Aneurysms ◽

Medical Community ◽

Patient Specific ◽

Therapy Planning ◽

Rotational Angiography ◽

Mean Velocity ◽

3D Images ◽

Computational Fluid Dynamics Cfd ◽

The Impact

AbstractComputational fluid dynamics (CFD) is increasingly used by biomedical engineering groups to understand and predict the blood flow within intracranial aneurysms and support the physician during therapy planning. However, due to various simplifications, its acceptance remains limited within the medical community. To quantify the influence of the reconstruction kernels employed for reconstructing 3D images from rotational angiography data, different kernels are applied to four datasets with patient-specific intracranial aneurysms. Sharp, normal and smooth reconstructions were evaluated. Differences of the resulting 24 segmentations and the impact on the hemodynamic predictions are quantified to provide insights into the expected error ranges. A comparison of the segmentations yields strong differences regarding vessel branches and diameters. Further, sharp kernels lead to smaller ostium areas than smooth ones. Analyses of hemodynamic predictions reveal a clear time and space dependency, while mean velocity deviations range from 3.9 to 8%. The results reveal a strong influence of reconstruction kernels on geometrical aneurysm models and the subsequent hemodynamic parameters. Thus, patient-specific blood flow predictions require a carefully selected reconstruction kernel and appropriate recommendations need to be formulated.

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Impact of Blockage on the Hydrodynamic Performance of Oscillating-Foils Hydrokinetic Turbines

Journal of Fluids Engineering ◽

10.1115/1.4033298 ◽

2016 ◽

Vol 138 (9) ◽

Cited By ~ 10

Author(s):

Etienne Gauthier ◽

Thomas Kinsey ◽

Guy Dumas

Keyword(s):

Operating Conditions ◽

Hydrodynamic Performance ◽

Blockage Ratio ◽

Cfd Simulations ◽

Hydrokinetic Turbines ◽

Marine Energy ◽

Computational Fluid Dynamics Cfd ◽

The Impact ◽

Do So ◽

Oscillating Foils

This paper describes a study of the impact of confinement on the hydrodynamic performance of oscillating-foils hydrokinetic turbines (OFHT). This work aims to contribute to the development of standards applying to marine energy converters. These blockage effects have indeed to be taken into account when comparing measurements obtained in flumes, towing tanks, and natural sites. This paper provides appropriate correction formula to do so for OFHT based on computational fluid dynamics (CFD) simulations performed at a Reynolds Number Re = 3 × 106 for reduced frequencies between f* = 0.08 and f* = 0.22 considering area-based blockage ratios ranging from ε = 0.2% to 60%. The need to discriminate between the vertical and horizontal confinement and the impact of the foil position in the channel are also investigated and are shown to be of second-order as compared to the overall blockage level. As expected, it is confirmed that the power extracted by the OFHT increases with the blockage level. It is further observed that for blockage ratio of less than ε = 40%, the power extracted scales linearly with ε. The approach proposed to correlate the performance of the OFHT in different blockage conditions uses the correction proposed by Barnsley and Wellicome and assumes a linear relation between the power extracted and the blockage. This technique is shown to be accurate for most of the practical operating conditions for blockage ratios up to 50%.

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Maximization of Solar Gains of an Air Collector by Simulations

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.284-287.483 ◽

2013 ◽

Vol 284-287 ◽

pp. 483-487 ◽

Cited By ~ 1

Author(s):

Ondrej Sikula ◽

Vit Merka ◽

Jiri Hirs ◽

Josef Plášek

Keyword(s):

Heat Transfer ◽

Solar Energy ◽

Solar Collector ◽

Cfd Simulations ◽

Ansys Fluent ◽

Operation Conditions ◽

Flow And Heat Transfer ◽

Solar Air Collector ◽

Computational Fluid Dynamics Cfd ◽

The Impact

The paper deals with numerical simulations of the impact of design, shading, positioning and orientation of a solar air collector an efficiency of exploitation of solar energy. The solar collector is used to preheat of an air, which then is supplied into the building. There are various requirements for solar air collectors. We are focused on maximization of solar energy gain by optimizing geometry, orientation and positioning of a solar air collector. To achieve the desired objective was a combination of two methods used. The firs one is Computational Fluid Dynamics (CFD) simulations of flow and heat transfer by convection, conduction and radiation in software ANSYS Fluent. The second one is the numerical simulation of the annual operations of the collector in the software BSim. The result of this work is an optimal design and operation conditions of the air collector.

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Vortex Analysis of Intra-Aneurismal Flow in Cerebral Aneurysms

Computational and Mathematical Methods in Medicine ◽

10.1155/2016/7406215 ◽

2016 ◽

Vol 2016 ◽

pp. 1-16 ◽

Cited By ~ 5

Author(s):

Kevin Sunderland ◽

Christopher Haferman ◽

Gouthami Chintalapani ◽

Jingfeng Jiang

Keyword(s):

Vortex Core ◽

Cardiac Cycle ◽

Temporal Stability ◽

Cerebral Aneurysms ◽

Patient Specific ◽

Cfd Simulations ◽

Hemodynamic Characteristics ◽

Computational Fluid Dynamics Cfd ◽

Marching Cube Algorithm ◽

Core Characteristics

This study aims to develop an alternative vortex analysis method by measuring structure ofIntracranial aneurysm (IA) flow vortexes across the cardiac cycle, to quantify temporal stability of aneurismal flow. Hemodynamics were modeled in “patient-specific” geometries, using computational fluid dynamics (CFD) simulations. Modified versions of knownλ2andQ-criterion methods identified vortex regions; then regions were segmented out using the classical marching cube algorithm. Temporal stability was measured by the degree of vortex overlap (DVO) at each step of a cardiac cycle against a cycle-averaged vortex and by the change in number of cores over the cycle. No statistical differences exist in DVO or number of vortex cores between 5 terminal IAs and 5 sidewall IAs. No strong correlation exists between vortex core characteristics and geometric or hemodynamic characteristics of IAs. Statistical independence suggests this proposed method may provide novel IA information. However, threshold values used to determine the vortex core regions and resolution of velocity data influenced analysis outcomes and have to be addressed in future studies. In conclusions, preliminary results show that the proposed methodology may help give novel insight toward aneurismal flow characteristic and help in future risk assessment given more developments.

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The Impact of Cardiac Motion on Aortic Valve Flow Used in Computational Simulations of the Thoracic Aorta

Journal of Biomechanical Engineering ◽

10.1115/1.4033964 ◽

2016 ◽

Vol 138 (9) ◽

Cited By ~ 2

Author(s):

David C. Wendell ◽

Margaret M. Samyn ◽

Joseph R. Cava ◽

Mary M. Krolikowski ◽

John F. LaDisa

Keyword(s):

Blood Flow ◽

Aortic Valve ◽

Coarctation Of The Aorta ◽

Outer Wall ◽

Cardiac Motion ◽

Patient Specific ◽

Flow Measurements ◽

Computational Fluid Dynamics Cfd ◽

Blood Flow Measurements ◽

The Impact

Advancements in image-based computational modeling are producing increasingly more realistic representations of vasculature and hemodynamics, but so far have not compensated for cardiac motion when imposing inflow boundary conditions. The effect of cardiac motion on aortic flow is important when assessing sequelae in this region including coarctation of the aorta (CoA) or regurgitant fraction. The objective of this investigation was to develop a method to assess and correct for the influence of cardiac motion on blood flow measurements through the aortic valve (AoV) and to determine its impact on patient-specific local hemodynamics quantified by computational fluid dynamics (CFD). A motion-compensated inflow waveform was imposed into the CFD model of a patient with repaired CoA that accounted for the distance traveled by the basal plane during the cardiac cycle. Time-averaged wall shear stress (TAWSS) and turbulent kinetic energy (TKE) values were compared with CFD results of the same patient using the original waveform. Cardiac motion resulted in underestimation of flow during systole and overestimation during diastole. Influences of inflow waveforms on TAWSS were greatest along the outer wall of the ascending aorta (AscAo) (∼30 dyn/cm2). Differences in TAWSS were more pronounced than those from the model creation or mesh dependence aspects of CFD. TKE was slightly higher for the motion-compensated waveform throughout the aortic arch. These results suggest that accounting for cardiac motion when quantifying blood flow through the AoV can lead to different conclusions for hemodynamic indices, which may be important if these results are ultimately used to predict patient outcomes.

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Test and Simulation of the Effects of Surface Roughness on a Shrouded Centrifugal Impeller

Volume 2D: Turbomachinery ◽

10.1115/gt2014-25480 ◽

2014 ◽

Cited By ~ 1

Author(s):

William T. Cousins ◽

Lei Yu ◽

Jacquelynn Garofano ◽

Barbara Botros ◽

Vishnu Sishtla ◽

...

Keyword(s):

Surface Roughness ◽

Cfd Simulation ◽

Centrifugal Impeller ◽

Test Results ◽

Cfd Simulations ◽

Computational Fluid Dynamics Cfd ◽

The Common ◽

R Value ◽

The Impact ◽

Grain Roughness

Surface roughness is an important parameter in the operational efficiency and loss development of turbomachinery components. Many computational fluid dynamics (CFD) simulations are performed on turbomachinery, but often one of the common assumptions is that the surfaces are hydraulically smooth. In this work, examination of the surfaces of two cast impellers is performed and compared to machined impellers with smoother surfaces. Both impeller sets were run in a two-stage industrial chiller unit using R134a refrigerant. Test results are presented and the impact of surface roughness modeling on the design is reviewed. Also discussed is the theory of the impact of roughness on turbulent boundary layers. Details about providing the CFD simulation with the proper sand grain roughness is discussed when surface finish (R-value) in microinches (μin) is measured.

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Multi-Scale, Patient-Specific Computational Flow Dynamics Models Predict Formation of Neointimal Hyperplasia in Saphenous Vein Grafts

10.1101/624312 ◽

2019 ◽

Author(s):

Francesca Donadoni ◽

Cesar Pichardo-Almarza ◽

Shervanthi Homer-Vanniasinkam ◽

Alan Dardik ◽

Vanessa Díaz-Zuccarini

Keyword(s):

Neointimal Hyperplasia ◽

Flow Dynamics ◽

Patient Specific ◽

Growth Mechanisms ◽

Cfd Simulations ◽

Vein Grafts ◽

Multi Scale ◽

Computational Flow Dynamics ◽

Computational Fluid Dynamics Cfd ◽

Dynamics Models

AbstractBypass occlusion due to neointimal hyperplasia (NIH) is among the major causes of peripheral graft failure. Its link to abnormal hemodynamics in the graft is complex, and isolated use of hemodynamic markers insufficient to fully capture its progression. Here, a computational model of NIH growth is presented, establishing a link between computational fluid dynamics (CFD) simulations of flow in the lumen, with a biochemical model representing NIH growth mechanisms inside the vessel wall. For all 3 patients analyzed, NIH at proximal and distal anastomoses was simulated by the model, with values of stenosis comparable to the computed tomography (CT) scans.

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