Abstract W P76: Parent Artery Curvature May Help Determine the Effectiveness of Flow Diverter Treatment

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Brando Dimapasoc ◽  
Aichi Chien
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Simulation Analysis ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Parent Artery ◽  
Flow Volume ◽  
Aneurysm Neck ◽  
Flow Reduction ◽  
Before And After

Introduction: Flow diverters (FDs) aim to treat intracranial aneurysms by altering intra-aneurysmal hemodynamics. Reports have suggested aneurysm and parent artery shape may affect flow reduction in FD-treatment. The purpose of this study is to gain insight into the way in which aneurysm shape and parent artery curvature influence the ability of FDs to redirect flow. Hypothesis: Aneurysm dome size and parent artery curvature affect FD-induced flow reduction within an aneurysm. Methods: FD models constructed based on the Pipeline Embolization Device with 35% area coverage, 30 um strand diameter, and 4 mm nominal diameter were implemented for hemodynamic simulation analysis. The flow reduction effects were tested using aneurysm models featuring different dome sizes and parent artery curvatures. Aneurysm blood flow was analyzed before and after FD stenting in regions of the aneurysm neck, body, and dome. Results: We found that aneurysms with higher parent artery curvature had increased systole flow volume entering aneurysms before and after stenting, regardless of aneurysm size, with pre-FD volume flow rates for curvatures of 20 and 30 degrees, respectively, 1.54 and 2.40 times those for 10 degree curvature. Furthermore, FD reduced flow less in aneurysms with higher curvature. For parent artery curvatures of 10, 20, and 30 degrees, overall reductions of flow volume entering the aneurysm were 91.1±0.56%, 88.2±1.2%, and 85.5±0.28%, respectively. 97.2% of models had more flow reduction at the aneurysm dome than neck. Figure 1 shows representative, post-FD flow in 10 and 30 degree parent arteries, with a greater volume flow rate in (b) depicted by denser streamlines. Aneurysm dome size was not found to have a significant effect on volume flow rate. Conclusions: We found that artery curvature may have a large influence on FD flow reduction, indicating that FD may be less effective at reducing blood flow entering aneurysms located within higher curvature arteries.

scholarly journals Effects of Arterial Pco2 and Cerebrospinal Fluid Volume Flow Rate Changes on Choroid Plexus and Cerebral Blood Flow in Normal and Experimental Hydrocephalic Cats

1983 ◽  
Vol 3 (3) ◽  
pp. 369-375 ◽  
Author(s):  
S. Nakamura ◽  
G. M. Hochwald
Keyword(s):  
Blood Flow ◽  
Cerebrospinal Fluid ◽  
Cerebral Cortex ◽  
Choroid Plexus ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Brain Blood Flow ◽  
Choroidal Blood Flow ◽  
Flow Rates

The effect of changes in brain blood flow on cerebrospinal fluid (CSF) volume flow rates, and that of changes in CSF volume flow rates on brain blood flow were determined in both normal and kaolin-induced hydrocephalic cats. In both groups of cats, blood flow in grey and white matter, cerebral cortex, and choroid plexus was measured with 105Ru microspheres during normocapnia, and again with 141Ce microspheres after arterial Pco2 was either increased by 300% or decreased by 50%. Blood flow measurements were also made during perfusion of the ventricular system with mock CSF and repeated during perfusion with anisosmotic mannitol solutions to alter CSF volume flow rate. In 30 normal and 26 hydrocephalic cats, blood flow to the cerebral cortex, white matter, and choroid plexus was similar; only blood flow to the caudate nucleus was greater in normal cats. The weight of the choroid plexus from hydrocephalic cats decreased by 17%. Blood flow in the choroid plexus of all cats decreased by almost 50% following hypercapnia or hypocapnia, without a change in the CSF volume flow rate. There was no change in cerebral or choroidal blood flow when CSF volume flow rate was either increased by 170% or decreased by 80%. These results suggest that choroid plexus blood flow does not limit or affect the volume flow rate of CSF from the choroid plexus. CSF volume flow rate can be altered without corresponding blood flow changes of the brain or choroid plexus. Choroid plexus blood flow and the reactivity of both brain and choroidal blood flow to changes in arterial Pco2 were not affected by the hydrocephalus. The lower CSF formation rate of hydrocephalic cats can be attributed in part to the decrease in the mass of choroid plexus tissue.

scholarly journals Saliva secretion difference before and after rinsing with baking soda on menopause women

2007 ◽  
Vol 19 (1) ◽  
Author(s):  
Dewi Anggraeni ◽  
Sri Tjahajawati ◽  
Rosiliwati Wihardja
Keyword(s):  
Statistical Analysis ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Volume Flow ◽  
Survey Method ◽  
Average Volume ◽  
Saliva Secretion ◽  
Significant Difference ◽  
Before And After ◽  
The Difference

Menopause women can experience a decrease in saliva secretion (decrease). To understand the clear picture about saliva secretion, the volume, flow rate, pH and viscosity were then measured. The aim of this research was to obtain a picture about the difference of saliva secretion before and after rinsing with baking soda on menopause women. The type of the research used was a laboratory quasi-experiment with comparative descriptive form. The technique used in this research is the survey method, and samples were taken using the multistage cluster random sampling method, and t-student statistical analysis. This research was conducted with the saliva collected with spitting method on 45 menopause women. The results show that the average volume, flow rate, pH and viscosity before rinsing with baking soda was 1.79 ml, 0.18 ml/minute, 7.40 and 0.81 mm2/second. The average volume, flow rate, pH and viscosity after rinsing with baking soda were 2.66 ml; 0.27 ml/minute; 8.67 and 0.78 mm2/second. Statistical analysis t-student on α = 0.05 shows volume changes, flow rate, pH and saliva viscosity before and after rinsing with baking soda was 0.873; 0.086; 1.273 and 0.037 respectively. The conclusion shows a significant difference between saliva secretion before and after rinsing with baking soda, and saliva secretion after rinsing with baking soda on menopause women.

P2427The development of a computational fluid dynamics pipeline for the study of tetralogy of Fallot and coarctation of the aorta in a developing world context

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
L Swanson ◽  
B Owen ◽  
A Revell ◽  
M Ngoepe ◽  
A Keshmiri ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Tetralogy Of Fallot ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Coarctation Of The Aorta ◽  
Volume Flow ◽  
Patient Specific ◽  
Data Set

Abstract Background Tetralogy of Fallot (ToF) and coarctation of the aorta (CoA) each constitute approximately 7% of congenital heart disease (CHD) births worldwide. Compared to developed countries, developing countries have a disparate level of access to prompt diagnosis and treatment for these diseases. Computational fluid dynamics (CFD) approaches implemented on routinely available non-invasive imaging data may yield low-cost improvements to the management of these patients. Purpose The purpose of this research is to develop a patient-specific computational pipeline that allows the modelling of blood flow in diseased arteries of patients suffering from ToF and CoA. The project aims to prove the feasible use of broadly available imaging techniques - CT angiograms (CTA) and echocardiographs (echo) - for achieving this in low-to-middle income countries. The capability of the pipeline will be demonstrated through a qualitative study of the effects of different systemic to pulmonary shunt configurations used in the palliative treatment of ToF. In addition, the effects of idealised stent configurations on the blood flow through the aorta of a patient with CoA will be studied. Methods A retrospective search through the hospital database was conducted to select suitable CTA data for a CoA and ToF case. Data for patient A, a five-month-old child with typical CoA, and patient B, a twelve-month-old child with typical ToF who had a central shunt in place, was found. Echo data was obtained for patient A through an investigation protocol which focused on CFD application whereas there was no echo data available for patient B. As a result, idealised volume flow rate data was implemented for patient B. Geometries for patient A and patient B were extracted and volume discretisation was implemented for grid independence testing. The Navier-Stokes governing equations for fluid flow were solved using the open source software, OpenFOAM, for the transient case where inlet volume flow rate was defined for four cardiac cycles. Figure 1 shows key features of the flow in the shunt and pulmonary branches (A), the aortic arch (B), the inlet at the ascending aorta (C) and the descending aorta (D) for the geometry extracted from the data set of patient B. Figure 1. Key flow features of patient B Results and discussion We have implemented CFD models which are able to qualitatively assess the favourable or unfavourable impact of different approaches to ToF and CoA repairs on the characteristics of blood flow in the aorta and pulmonary arteries. An echo investigation protocol has been developed and successfully applied. CTA studies have been shown as feasible sources of geometry data in spite of the restriction on quality by the important requirement for low doses of radiation in paediatric patients. This project represents progress towards an advanced tool that may be broadly implemented in both well-resourced and minimally-resourced hospitals. Acknowledgement/Funding National Research Fund, British Heart Foundation, Newton Fund (UK MRC, South African Medical Research Council), University of Cape Town

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

Multi-objective optimization of squirrel cage fan for range hood based on Kriging model

2021 ◽  
pp. 095440622199586
Author(s):  
Qianhao Xiao ◽  
Jun Wang ◽  
Boyan Jiang ◽  
Weigang Yang ◽  
Xiaopei Yang
Keyword(s):  
Flow Rate ◽  
Optimization Design ◽  
Volume Flow Rate ◽  
Kriging Model ◽  
Volume Flow ◽  
Design Parameters ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Multi Objective ◽  
Squirrel Cage

In view of the multi-objective optimization design of the squirrel cage fan for the range hood, a blade parameterization method based on the quadratic non-uniform B-spline (NUBS) determined by four control points was proposed to control the outlet angle, chord length and maximum camber of the blade. Morris-Mitchell criteria were used to obtain the optimal Latin hypercube sample based on the evolutionary operation, and different subsets of sample numbers were created to study the influence of sample numbers on the multi-objective optimization results. The Kriging model, which can accurately reflect the response relationship between design variables and optimization objectives, was established. The second-generation Non-dominated Sorting Genetic algorithm (NSGA-II) was used to optimize the volume flow rate at the best efficiency point (BEP) and the maximum volume flow rate point (MVP). The results show that the design parameters corresponding to the optimization results under different sample numbers are not the same, and the fluctuation range of the optimal design parameters is related to the influence of the design parameters on the optimization objectives. Compared with the prototype, the optimized impeller increases the radial velocity of the impeller outlet, reduces the flow loss in the volute, and increases the diffusion capacity, which improves the volume flow rate, and efficiency of the range hood system under multiple working conditions.

scholarly journals Influence of Magnetic Field on the Peristaltic Flow of a Viscous Fluid through a Finite-Length Cylindrical Tube

2010 ◽  
Vol 7 (3) ◽  
pp. 169-176 ◽  
Author(s):  
S. K. Pandey ◽  
Dharmendra Tripathi
Keyword(s):  
Magnetic Field ◽  
Viscous Fluid ◽  
Transverse Magnetic Field ◽  
Finite Length ◽  
Flow Rate ◽  
Hartmann Number ◽  
Volume Flow Rate ◽  
Critical Value ◽  
Transverse Magnetic ◽  
Volume Flow

The paper presents an analytical investigation of the peristaltic transport of a viscous fluid under the influence of a magnetic field through a tube of finite length in a dimensionless form. The expressions of pressure gradient, volume flow rate, average volume flow rate and local wall shear stress have been obtained. The effects of the transverse magnetic field and electrical conductivity (i.e. the Hartmann number) on the mechanical efficiency of a peristaltic pump have also been studied. The reflux phenomenon is also investigated. It is concluded, on the basis of the pressure distribution along the tubular length and pumping efficiency, that if the transverse magnetic field and the electric conductivity increase, the pumping machinery exerts more pressure for pushing the fluid forward. There is a linear relation between the averaged flow rate and the pressure applied across one wavelength that can restrain the flow due to peristalsis. It is found that there is a particular value of the averaged flow rate corresponding to a particular pressure that does not depend on the Hartmann number. Naming these values ‘critical values’, it is concluded that the pressure required for checking the flow increases with the Hartmann number above the critical value and decreases with it below the critical value. It is also inferred that magneto-hydrodynamic parameters make the fluid more prone to flow reversal. The conclusion applied to oesophageal swallowing reveals that normal water is easier to swallow than saline water. The latter is more prone to flow reversal. A significant difference between the propagation of the integral and non-integral number of waves along the tube is that pressure peaks are identical in the former and different in the latter cases.

Partial Admission, Axial Impulse Type Turbine Design and Partial Admission Radial Turbine Test for SCO2 Cycle

2017 ◽  
Author(s):  
Hyungki Shin ◽  
Junhyun Cho ◽  
Young-Jin Baik ◽  
Jongjae Cho ◽  
Chulwoo Roh ◽  
...  
Keyword(s):  
Axial Force ◽  
Flow Rate ◽  
Volume Flow Rate ◽  
Small Diameter ◽  
Volume Flow ◽  
Working Fluid ◽  
Rotating Speed ◽  
Turbo Generator ◽  
Partial Admission ◽  
Reduce Development Time

Power generation cycle — typically Brayton cycle — to use CO2 at supercritical state as working fluid have been researched many years because this cycle increase thermal efficiency of cycle and decrease turbomachinery size. But small turbomachinery make it difficult to develop proto type Supercritical Carbon dioxide (S-CO2) cycle equipment of lab scale size. KIER (Korea Institute of Energy Research) have been researched S-CO2 cycle since 2013. This paper is about 60kWe scale and sub-kWe class turbo generator development for applying to this S-CO2 cycle at the lab scale. A design concept of this turbo-generator is to use commercially available components so as to reduce development time and increase reliability. Major problem of SCO2 turbine is small volume flow rate and huge axial force. High density S-CO2 was referred as advantage of S-CO2 cycle because it make small turbomachinery possible. But this advantage was not valid in lab-scale cycles under 100kW because small amount volume flow rate means high rotating speed and too small diameter of turbine to manufacture it. Also, high inlet and outlet pressure make huge axial force. To solve these problem, KIER have attempt various turbines. In this paper, these attempts and results are presented and discussed.

Numerical Simulation on Air Volume Flow Rate Distribution of Stator Ducts for Salient Pole Synchronous Motor

2014 ◽  
Vol 644-650 ◽  
pp. 373-376
Author(s):  
Li Liu ◽  
Yi Ping Lu ◽  
Jia De Han ◽  
Xue Mei Sun
Keyword(s):  
Flow Rate ◽  
Volume Flow Rate ◽  
Domain Boundary ◽  
Air Flow ◽  
Flow Characteristics ◽  
Synchronous Motor ◽  
Volume Flow ◽  
Rate Distribution ◽  
Salient Pole ◽  
Air Volume

Air volume flow rate distribution of stator ducts along axial and circumferential for salient pole synchronous motor is strongly influenced by the air flow field in the air gap and rotor poles, which is completely different from the flow characteristics of non-salient pole motor and it directly relates to the peak temperature of stator bars and core and axial temperature difference which can affect the safety of the operation. A three-dimensional physical model of 1/8 motor was established and corresponding solution domain boundary conditions were given in this article. The air volume flow rate distribution of stator ducts along axial and circumferential was analyzed based on CFD. The study show that at the same position of the axial stator, the cooling air flow into stator ducts along the circumferential direction is uneven, the air volume flow rate distribution is largely influenced by rotor pole pieces, geometry and position of pole support block and rotor rotation direction.

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