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

PLoS ONE ◽  
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.

scholarly journals De-risking flight trials using airwake simulations

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.

CFD and Experimental Analysis of Centrifugal Fans With Forward Curved Blades Used in Electric Motors

2019 ◽  
Author(s):  
S. S. Borges
Keyword(s):  
Cfd Simulation ◽  
Experimental Tests ◽  
Performance Comparison ◽  
Centrifugal Fan ◽  
Electric Motors ◽  
Cfd Simulations ◽  
Interface Models ◽  
Ansys Cfx ◽  
Centrifugal Fans ◽  
Computational Fluid Dynamics Cfd

Abstract This work presents an analysis of the aerodynamic performance of a centrifugal fan with forward curved blades (Sirocco) applied to electric motors. In this analysis were carried out computational fluid dynamics (CFD) simulations and experimental tests for comparison of results. The focus of this analysis is the performance comparison among three different models of general connection interface that are required for the connection between the grids of the rotating and stationary domains of CFD simulation, considering the method adopted by the Ansys CFX, software used as computational tool. Thereby, Frozen Rotor, Stage, and Transient Rotor-Stator were the interface models evaluated. For comparison reference, the experimental data were used to evaluate the performance of each interface models for overall operating range of the fan.

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

2016 ◽  
Vol 138 (9) ◽  
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%.

Maximization of Solar Gains of an Air Collector by Simulations

2013 ◽  
Vol 284-287 ◽  
pp. 483-487 ◽  
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.

Multiphase Computation of Cavitation Breakdown in Model and Prototype Scale Francis Turbines

2015 ◽  
Author(s):  
Daniel J. Leonard ◽  
Jules W. Lindau
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Qualitative And Quantitative ◽  
Machine Performance ◽  
Computational Fluid Dynamics Cfd ◽  
Stage Analysis ◽  
Reduced Scale ◽  
Francis Hydroturbine

Steady-periodic multiphase Computational Fluid Dynamics (CFD) simulations were conducted to capture cavitation breakdown in a Francis hydroturbine due to large-scale vaporous structures. A reduced-scale model and a full-scale prototype were investigated to display differences in vapor content and machine performance caused by lack of Reynolds and Froude similarity. The model scale efficiencies compared favorably (within 3%) to the experimental cavitation tests. The CFD model and prototype displayed distinct qualitative and quantitative differences as σ was reduced. A stage-by-stage analysis was conducted to assess the effect of cavitation on loss distribution throughout the machine. Furthermore, a formal mesh refinement study was conducted on efficiency and volume of vapor, with three mesh levels and Richardson extrapolation, to ensure convergence.

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

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 839
Author(s):  
Unai Lertxundi ◽  
Jorge Aramburu ◽  
Julio Ortega ◽  
Macarena Rodríguez-Fraile ◽  
Bruno Sangro ◽  
...  
Keyword(s):  
Hepatic Artery ◽  
Liver Parenchyma ◽  
Patient Specific ◽  
Proof Of Concept ◽  
Cfd Simulations ◽  
Intraarterial Infusion ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact ◽  
Healthy Liver ◽  
Simulation Time

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.

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

2014 ◽  
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.

Modeling of a Gas Leakage Including Droplet Transport

2004 ◽  
Author(s):  
G. Polanco ◽  
A. E. Holdo̸
Keyword(s):  
Safety Assessment ◽  
Gas Distribution ◽  
Gas Leakage ◽  
Droplet Concentration ◽  
Droplet Transport ◽  
Compressed Liquid ◽  
Gas Leak ◽  
Compressed Gas ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

Safety assessment of compressed gas storage and pipeline facilities has to consider accidental leaks to the atmosphere. A major concern for modelling of such accidental leaks is the phase change behaviour of the compressed (liquid) gas. The present study assumes that droplets of the liquid gas are present in the gas leak jet. The effect of the droplet concentration and diameter on the behaviour on the jet is studied using Computational Fluid Dynamics (CFD). The impact of these variables on local gas distribution is analysed and discussed.

Influence of Tip Jet Mass Flow and Blowing Rate on the Performance of an Axial Diffuser at Different Inlet Total Pressure Profiles

2015 ◽  
Author(s):  
Rojas Thomas ◽  
Markus Schatz ◽  
Benjamin Kuschel ◽  
Silke Brouwer ◽  
A. M. Pradeep ◽  
...  
Keyword(s):  
Mass Flow ◽  
Total Pressure ◽  
Pressure Recovery ◽  
Jet Flows ◽  
Cfd Simulations ◽  
Blowing Ratio ◽  
Pressure Profiles ◽  
Mass Flow Rates ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

The present paper evaluates the impact of casing energized jet flow on the performance of an annular-conical exhaust diffuser. Two different inflow profiles, namely a uniform total pressure and a hub-strong total pressure inlet profile were studied. For both profiles, the flow is observed to separate at the casing. Experiments were performed at different tip jet mass flow rates and two different tip gap heights to understand their effect on the diffuser performance. Apart from wall pressure readings, probe measurements have been done at various locations within the diffuser to study the flow behaviour in more detail. The results show that at the diffuser inlet already small tip jet flows help to prevent casing separation and hence improve pressure recovery noticeably, especially in the front section of the diffuser. On the other hand, higher tip jet flows tend to weaken the core flow at the diffuser exit, thus generating an inhomogeneous outflow velocity profile. To enhance the interpretation of the experimental data, results from Computational Fluid Dynamics (CFD) simulations are used. Interestingly, the experimental results indicate that while the blowing ratio seems to be the major parameter for the improvement of pressure recovery for a hub-strong inlet profile, the pressure recovery for a uniform profile appears to be more sensitive to the tip jet mass flow rate. However, the numerical results do not show this trend.

scholarly journals Hemodynamic Investigation of the Effectiveness of a Two Overlapping Flow Diverter Configuration for Cerebral Aneurysm Treatment

2021 ◽  
Vol 8 (10) ◽  
pp. 143
Author(s):  
Yuya Uchiyama ◽  
Soichiro Fujimura ◽  
Hiroyuki Takao ◽  
Takashi Suzuki ◽  
Motoharu Hayakawa ◽  
...  
Keyword(s):  
Cfd Simulation ◽  
Cerebral Aneurysms ◽  
Flow Diverter ◽  
Cfd Simulations ◽  
Qualitative And Quantitative ◽  
Pressure Loss Coefficient ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
Wide Neck ◽  
Flow Diverters

Flow diverters (FDs) are widely employed as endovascular treatment devices for large or wide-neck cerebral aneurysms. Occasionally, overlapped FDs are deployed to enhance the flow diversion effect. In this study, we investigated the hemodynamics of overlapping FDs via computational fluid dynamics (CFD) simulations. We reproduced the arterial geometry of a patient who had experienced the deployment of two overlapping FDs. We utilized two stent patterns, namely the patterns for one FD and two overlapping FDs. We calculated the velocity, mass flow rate, wall shear stress, and pressure loss coefficient as well as their change rates for each pattern relative to the no-FD pattern results. The CFD simulation results indicated that the characteristics of the blood flow inside the aneurysm were minimally affected by the deployment of a single FD; in contrast, the overlapping FD pattern results revealed significant changes in the flow. Further, the velocity at an inspection plane within the aneurysm sac decreased by up to 92.2% and 31.0% in the cases of the overlapping and single FD patterns, respectively, relative to the no-FD pattern. The simulations successfully reproduced the hemodynamics, and the qualitative and quantitative investigations are meaningful with regard to the clinical outcomes of overlapped FD deployment.

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