Vortex Dynamics in Sidewall Aneurysms: Hemodynamic Transition During Growth and Clinical Implications

2017 ◽  
Author(s):  
Trung Bao Le ◽  
Fotis Sotiropoulos
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Vortex Dynamics ◽  
Loading Condition ◽  
Aneurysm Rupture ◽  
Clinical Implications ◽  
Aneurysmal Wall ◽  
Flow Pulsatility ◽  
The Impact

Recent works have suggested that aneurysm size and shape might not be the only indicators to predict aneurysm rupture. Rather, the long-term interaction between hemodynamics and aneurysmal wall via the loading condition (i.e shear stress and pressure) may also be important. In this work, we investigate the impact of flow pulsatility on the hemodynamic patterns on aneurysmal dome during its growth using numerical simulation.

scholarly journals Investigations on the Impact of Using Elliptic Groynes on the Flow in Open Channels

2021 ◽  
Vol 27 (2) ◽  
pp. 44-58
Author(s):  
Ahmed M. Hussein AL‏-‏Sarefi ◽  
Riyadh Z. Azzubaidi
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Good Accuracy ◽  
Open Channels ◽  
Bed Shear Stress ◽  
Cfd Model ◽  
Good Ability ◽  
Bed Slope ◽  
The Impact

This paper presents a numerical simulation of the flow around elliptic groynes by using CFD ‎software. The flow was simulated in a flume with 4m long, 0.4m wide, ‎and 0.175m ‎high ‎‎with a constant bed slope. Moreover, the first Groyne placed at 1m from the flow ‎‎inlet with a ‎constant the Groyne height of 10cm and a 1cm thickness, and the ‎width of Groynes equals ‎7cm‎. A submergence ratio of the elliptic Groynes of 75% was assumed, corresponding to a discharge of ‎0.0057‎m3/sec. The CFD ‎model showed a good ability to simulate the flow ‎around ‎Groynes with ‎ good accuracy. The results of ‎CFD software showed that when using double elliptic Groynes, the bed shear stress is decreased with the ‎increase in the spacing between Groynes, as well as and the best spacing between the double ‎elliptic Groynes is twice of the Groyne width. Moreover, the used number of Groynes has no ‎much ‎impact ‎on velocity and shear ‎stress values.

Effects of the Non-Newtonian Viscosity of Milk Flow in the Breast Ductal System

2019 ◽  
Author(s):  
Jamasp Azarnoosh ◽  
Fatemeh Hassanipour
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Newtonian Fluid ◽  
Flow Properties ◽  
Newtonian Viscosity ◽  
Ductal System ◽  
Milk Flow ◽  
Clinical Investigations ◽  
Fluid Wall Shear Stress ◽  
The Impact

Abstract Numerical simulation of human milk flow inside the breast ductal system is carried out to investigate the impact of milk flow properties, specifically viscosity, on the flow regime. The geometry of the ductal system is assumed as a rigid body with six bifurcation levels. The vacuum pressure, obtained from clinical investigations, is applied as boundary conditions for numerical analysis. The simulations are performed by considering both Newtonian and Non-Newtonian milk flow properties. The streamlines of velocity fluid, wall shear stress, and milk flow expression for these two models are discussed. The results show that the non-Newtonian fluid has a higher magnitude of velocity compared to the Newtonian fluid, which leads to a greater amount of milk expression.

An experimental and numerical investigation on impact spot welding of metallic plates using gas mixture detonation technique

2020 ◽  
pp. 146442072098232
Author(s):  
Sedigheh Hosseinzadeh ◽  
Hashem Babaei ◽  
Tohid Mirzababaie Mostofi
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Plastic Strain ◽  
Spot Welding ◽  
Equivalent Plastic Strain ◽  
Welding Process ◽  
Gas Mixture ◽  
The Impact ◽  
Base Plates ◽  
Metallic Plates

In this paper, the impact spot welding of metallic plates was investigated both experimentally and numerically using a single-stage gas mixture detonation apparatus. The impact spot welding process was carried out on aluminum alloy and steel materials using rigid steel projectiles. In this process, the mixture of oxygen and acetylene was detonated in a combustion chamber to launch the projectile. The masses of flat- and spherical-nosed projectiles were 270 and 230 g, respectively. The impact velocity was measured in all experiments. The cross-sections of the weld spots were inspired by a scanning electron microscope to assess the quality of welding. For several experiments, wavy interfaces were observed showing there is a good bonding. For numerical simulation of the process, Abaqus/Explicit software was used and the deformation and failure mechanisms of impact spot-welded specimens were further investigated. The Johnson–Cook thermoplasticity model along with its failure model was utilized to predict the behavior of metallic materials. The numerical simulation results were in good agreement with those obtained from experiments in terms of the deformation mode and failure pattern. The propagation of the wave on the surface of the flyer plate was further studied. The results showed that the stress waves start from the center and propagate to the corners of the plate. To numerically evaluate the welding quality, two parameters of the shear stress at the collision point as well as the equivalent plastic strain for the flyer and target plates were obtained in the numerical simulation. The numerical results showed opposite directions of shear stress for flyer and base plates at the contact point, which can be used as proof for good bonding. Besides, the magnitudes of the equivalent plastic strain for both flyer and base plates were higher than those reported values in the open literature that confirms successful welding.

scholarly journals Impact of homicide by a psychiatric patient on forensic psychiatrists: national survey

2020 ◽  
pp. 1-7
Author(s):  
Gillian Mezey ◽  
Renarta Rowe ◽  
Gwen Adshead
Keyword(s):  
Physical Health ◽  
Royal College ◽  
Telephone Interview ◽  
Professional Life ◽  
Personal Life ◽  
Clinical Implications ◽  
Support Needs ◽  
The Uk ◽  
The Impact

Aims and method To explore the experiences and support needs of consultant forensic psychiatrists, whose patients had committed homicide while under their care. We circulated a survey to all forensic psychiatrists in the UK, through the Royal College of Psychiatrists, asking about their experiences of a homicide by a patient under their care. Respondents were invited to discuss their experiences further in a structured telephone interview and themes were identified from these discussions. Data were analysed quantitatively and qualitatively. Results One-third of the 86 respondents had had at least one patient who had committed a homicide while under their care. Of these, over three-quarters (78%) reported that the homicide had a significant impact on their personal life, professional life and/or mental/physical health. For some respondents, the impact was severe and long term. Respondents generally felt that they would have been helped by receiving more support in the aftermath of the homicide. Clinical implications Greater recognition is needed of the impact on treating psychiatrists of homicide by a patient and more support is needed for affected clinicians. Further research is necessary, including the effects of such events on colleagues in other specialties and examination of the costs versus the benefits of mandatory inquiries after homicides.

Numerical Simulation of Blood-Wall Albumin Transport in a Realistic Human Right Coronary Artery

2007 ◽  
Author(s):  
Nanfeng Sun ◽  
Ryo Torii ◽  
Nigel B. Wood ◽  
Andrew Wright ◽  
Alun D. Hughes ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Coronary Artery ◽  
Endothelial Dysfunction ◽  
Wall Shear Stress ◽  
Right Coronary Artery ◽  
Flow Conditions ◽  
Human Right ◽  
Wall Model ◽  
Flow Pulsatility

Low wall shear stress (WSS) is commonly implicated in endothelial dysfunction and atherogenesis. The accumulation of macromolecules is also considered as an important factor contributing to the development of atherosclerosis. In the present study a fluid-wall model, incorporating shear-dependent endothelial transport properties, was developed and used to study the transport of albumin from blood to and within the wall in a realistic human right coronary artery (RCA). Numerical simulations were performed at both steady and pulsatile flow conditions, and results were compared to evaluate the effect of flow pulsatility.

scholarly journals The Impact of Erythrocytes Injury on Blood Flow in Bionic Arteriole with Stenosis Segment

Processes ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 372 ◽  
Author(s):  
Donghai Li ◽  
Guiling Li ◽  
Yuanyuan Chen ◽  
Jia Man ◽  
Qingyu Wu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Blood Cell ◽  
Microfluidic Device ◽  
Flow Patterns ◽  
High Shear ◽  
High Shear Stress ◽  
The Impact ◽  
Rheometer Test

Ventricular assist device (VAD) implantation is an effective treatment for patients with end-stage heart failure. However, patients who undergo long-term application of VADs experience a series of VAD-related adverse effects including pump thrombosis, which is induced by rotate impeller-caused blood cell injury and hemolysis. Blood cell trauma-related flow patterns are the key mechanism for understanding thrombus formation. In this study, we established a new method to evaluate the blood cell damage and investigate the real-time characteristics of blood flow patterns in vitro using rheometer and bionic microfluidic devices. The variation of plasma free hemoglobin (PFH) and lactic dehydrogenase (LDH) in the rheometer test showed that high shear stress was the main factor causing erythrocyte membrane injury, while the long-term exposure of high shear stress further aggravated this trauma. Following this rheometer test, the damaged erythrocytes were collected and injected into a bionic microfluidic device. The captured images of bionic microfluidic device tests showed that with the increase of shear stress suffered by the erythrocyte, the migration rate of damaged erythrocyte in bionic microchannel significantly decreased and, meanwhile, aggregation of erythrocyte was clearly observed. Our results indicate that mechanical shear stress caused by erythrocyte injury leads to thrombus formulation and adhesion in arterioles.

Damage Equivalent of the Flexible Pavement Variation with Load Applied

2013 ◽  
Vol 405-408 ◽  
pp. 1917-1922 ◽  
Author(s):  
Rosnawati Buhari ◽  
Saifullizam Puteh
Keyword(s):  
Influence Function ◽  
Loading Condition ◽  
Primary Response ◽  
Traffic Loading ◽  
Damage Prediction ◽  
Load Variation ◽  
Damage Law ◽  
Pavement Damage ◽  
The Impact

Previous research revealed that influence function is strongly influenced the appropriateness of pavement damage prediction and are demanding to be concern in order for better prediction of long term pavement performance. In order to identify the impact of traffic loading condition on the influence function of the pavement toward failure, further stucdy was done to determine the exponential value in the Damage Equivalent Law for varies loading condition and also vehicle speeds. To achieve the aims, the simple quarter truck model was efficiently used with personal computers to predict pavement loading. Towards reality of traffic loading condition will contain a distribution of axles load between unladen and fully laden, the study was further taking into account realistic axle load variation. Results are presented from a study to evaluate the relative influence of truck speed and axle load variation on the stiffness of the asphaltic layer and thus the primary response of the pavement. In conclusion, the exponential value in the Equivalent Damage Law is clearly sensitive to both factor.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Examining the Impact of the Disabled Youth Peer Development Initiative: What are the Long-Term Outcomes?

2003 ◽  
Author(s):  
Teresa Garate-Serafini ◽  
Jose Mendez ◽  
Patty Arriaga ◽  
Larry Labiak ◽  
Carol Reynolds
Keyword(s):  
Long Term Outcomes ◽  
The Disabled ◽  
The Impact
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