Comparison of Aneurismal Hemodynamics Between 4-D Accelerated Phase-Contrast MR Angiography and Computational Fluid Dynamics Simulations: Initial Experience in a Canine Aneurysm Model

2010 ◽  
Author(s):  
Jingfeng Jiang ◽  
Kevin Johnson ◽  
Kristian Valen-Sendstad ◽  
Kent-Andre Mardal ◽  
Dan Consigny ◽  
...  
Keyword(s):  
Blood Flow ◽  
Therapeutic Interventions ◽  
Cfd Simulations ◽  
Stent Deployment ◽  
Blood Flow Imaging ◽  
Flow Information ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Realistic Geometries ◽  
Aneurysm Model

The etiology and progression of intracranial aneurysms (IAs) are closely associated with complex patterns of disturbed blood flow. [1] Consequently, blood flow imaging [2] and CFD simulations in realistic geometries [3, 4] are of clinical interests because flow information obtained by such techniques can provide insight not only into the development and progression of IAs but also into their responses to therapeutic interventions (e.g. coil embolization and stent deployment).

A Method for Gray-Scale Imaging of Blood Flow Using High-Frequency Ultrasound

2017 ◽  
Vol 40 (1) ◽  
pp. 3-14
Author(s):  
Jun Yang ◽  
Chao Pang ◽  
Xue-Dong Song ◽  
Xuan Gao
Keyword(s):  
Blood Flow ◽  
High Frequency ◽  
Single Pulse ◽  
Frequency Range ◽  
High Frequency Ultrasound ◽  
Blood Flow Imaging ◽  
Blood Flow Signal ◽  
Flow Information ◽  
Blood Imaging ◽  
Frequency Ultrasound

This paper presents a new method that complements current techniques available in the high-frequency blood imaging field. A comprehensive scattering model was established to determine the feasibility and frequency range of the blood flow imaging of superficial organs and tissues using high-frequency ultrasound. The transmitting and receiving modes and an algorithm were designed to obtain blood flow information based on differentiation between tissues and blood flow. The system was created and tested first with a model that simulates blood flow and was then used on human tissue. A fine-scale image of a blood vessel could be obtained with this system. Moreover, this method can obtain weak blood flow signal using single pulse rather than the traditional pulse-code method and maintains a high resolution that can be matched to high-frequency structural imaging. This study provides a reliable method for further applications related to diagnoses of superficial organs.

scholarly journals CFD simulations of rotary BOF slag carbonation kiln reactor with cyclone flow

2019 ◽  
Vol 234 (1) ◽  
pp. 37-45
Author(s):  
Tong-Bou Chang ◽  
Cho-Yu Lee ◽  
Ming-Sheng Ko ◽  
Chin-Fong Lim
Keyword(s):  
Residence Time ◽  
Rotary Kiln ◽  
Basic Oxygen Furnace ◽  
Cfd Simulations ◽  
Carbonation Reaction ◽  
Carbonation Process ◽  
Taguchi Experimental Method ◽  
Bof Slag ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Rotary kiln reactors play an important role in improving the mechanical properties and usability of basic oxygen furnace slag through a carbonation process. The performance of such reactors is critically dependent on the residence time of the CO2 gas used to promote the carbonation reaction. Accordingly, the present study proposes a rotary kiln reactor in which the residence time is increased by arranging the inlet and outlet pipes obliquely to the reactor centerline; thereby producing a cyclone flow structure within the reactor tube. The optimal geometry parameters and rotational speed of the kiln are determined using the robust Taguchi experimental method. The CO2 residence time in the optimized kiln is then evaluated by means of computational fluid dynamics simulations. It is shown that the residence time increases from 63.587 s in a standard (non-cyclone-flow) rotary kiln to 105.815 s in the optimized rotary kiln; corresponding to a performance improvement of 66.4%.

scholarly journals CFD Simulations of Splash Losses of a Gearbox

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Carlo Gorla ◽  
Franco Concli ◽  
Karsten Stahl ◽  
Bernd-Robert Höhn ◽  
Michaelis Klaus ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Experimental Results ◽  
Operating Parameters ◽  
Main Concern ◽  
Design Phase ◽  
Power Losses ◽  
Cfd Simulations ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Efficiency is becoming a main concern in the design of power transmissions. It is therefore important, especially during the design phase, to have appropriate models to predict the power losses. For this reason, CFD (computational fluid dynamics) simulations were performed in order to understand the influence of geometrical and operating parameters on the losses in power transmissions. The results of the model were validated with experimental results.

scholarly journals Digital Subtraction Angiography Contrast Material Transport as a Direct Assessment for Blood Perfusion of Middle Cerebral Artery Stenosis

2021 ◽  
Vol 12 ◽  
Author(s):  
Yun-Hao Lu ◽  
Yan Cai ◽  
Yi Zhang ◽  
Rui Wang ◽  
Zhi-Yong Li
Keyword(s):  
Blood Flow ◽  
Middle Cerebral Artery ◽  
Digital Subtraction Angiography ◽  
Cerebral Artery ◽  
Contrast Material ◽  
Blood Perfusion ◽  
Digital Subtraction ◽  
Material Transport ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Digital subtraction angiography (DSA) is a fluoroscopic technique used extensively in interventional radiology for visualizing blood vessels. It has also been used to evaluate blood perfusion. However, the perfusion obtained in previous techniques was extracted from signal intensity rather than by the transport of contrast material (CM) through blood flow. The main aim of this study is to evaluate the morphological effects on the hemodynamics and the CM concentration in the middle cerebral artery (MCA) stenosis. We proposed a quantitative parameter, i.e., contrast material remaining time (CMRT), to describe the variation in the transport of CM over time. Computational fluid dynamics simulations were performed on both reconstructive synthetic and patient-derived models. In the synthetic models, we evaluated the variation of flow patterns and the transport of CM with different degrees of stenosis and the location of the lesion. It was found that an increase in the degree of stenosis (from 30 to 80%) resulted in a significant increase in CMRT at the anterior cerebral artery (ACA) outlet (p = 0.0238) and a significant decrease in CMRT at the MCA outlet (p = 0.012). The patient-derived models were reconstructed from the pre- and post-interventional DSA images of a patient with MCA stenosis. Both blood flow velocity and CMRT increased at the ACA outlet but decreased at the MCA outlet. The perfusion analysis demonstrated that the perfusion function was improved after interventional surgery. In conclusion, changes in stenotic degree at MCA may lead to apparent differences in the hemodynamic distribution and the transport of CM. CMRT could be a quantitative indicator to evaluate the changes in blood perfusion after the intervention for MCA stenosis.

Design of Fire Ventilation System for an Underground Car Park by CFD Simulations

2019 ◽  
Vol 887 ◽  
pp. 459-466
Author(s):  
Miroslava Kmecová ◽  
Peter Buday ◽  
Jozef Vojtaššák ◽  
Michal Krajčík
Keyword(s):  
Fluid Flow ◽  
Ventilation System ◽  
Computer Software ◽  
Contamination Level ◽  
Cfd Simulations ◽  
Car Park ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Fluid Behaviour ◽  
Two Alternatives

The aim of this study is to design a fire ventilation system with impulse jet fans for an underground car park. During the planning, it is necessary to consider all aspects of fluid behaviour however, there is a number of parameters that can affect the flow of smoke that need to be considered. There is a good chance of miscalculations when computing the overall fluid flow using conventional plain calculations. To avoid mistakes, visualize the fluid flow and also to directly compare the different design variants it can be practical to use computer software, specifically CFD (Computational Fluid Dynamics) simulations. By CFD it is possible to better analyse and keep control of the flow of fluid, heat transfer and other related phenomena. It also helps predict the contamination level of Carbon Monoxide, heat and smoke intensity and distribution. In this study CFD simulations were used to design, test and compare two alternatives of fire ventilation system. The two alternatives differed from each other in the location of the impulse jet fans and exhaust ventilation shafts, and in the ventilation intensity (10-times per hour in the first alternative and 15-times per hour in the second alternative). The results have shown that the first alternative is not suitable as the car park was not sufficiently ventilated after 1500 seconds after the simulation had begun, whereas in the second alternative the smoke was almost completely exhausted and the visibility was significantly improved. The simulation results emphasize the important effect of design and location of the different elements on the functionality and efficiency of a fire protection system.

Depression of Collateral Blood Flow Following Arterial Thrombosis

1977 ◽  
Vol 38 (04) ◽  
pp. 0850-0862 ◽  
Author(s):  
Robert G. Schaub ◽  
Ronald Sande ◽  
Kenneth M. Meyers
Keyword(s):  
Blood Flow ◽  
Arterial Thrombosis ◽  
Hind Limb ◽  
Therapeutic Interventions ◽  
Collateral Blood Flow ◽  
Serotonin Antagonist ◽  
Limb Perfusion ◽  
Clinical Consequences ◽  
Collateral Vessels ◽  
Iliac Bifurcation

SummaryPermanent ligation of the feline aorta at the iliac bifurcation is followed by rapid opening of pre-existing collateral blood vessels. However, if ligation is combined with formation of a clot, these protective collateral vessels do not function. This study was undertaken to determine if drugs which alter serotonin function can improve collateral blood flow after arterial thrombosis. Permanent ligations were placed at the iliac bifurcation, circumflex iliac and sixth lumbar arteries in all cats. A clot was produced in the aorta of 27 cats by injection of 0.1 ml of thromboplastin. Ligated clot-occluded cats were untreated (10); had blood serotonin depleted using a single dose of reserpine (0.1 mg/kg i. m.) followed by para-chlorophenylanine (p-CPA) (100 mg/kg orally) every 3 days (9) ; or were treated prior to surgery with a serotonin antagonist cinanserin HC1 (4 mg/kg i. v.) (8). Control cats (18) were acutely ligated. 9 of these cats were untreated, 5 were cinanserin HC1-treated, and 4 were reserpine/p-CPA-treated. Extent of collateral development was assessed by aortograms 3 days after occlusion and by neurologic rating. Aortograms of acutely ligated cats indicated a significant collateral blood flow around the segment of ligated aorta, while ligated clot-occluded cats had a severely depressed hind-limb perfusion. Reserpine/p-CPA-treated ligation clot-occluded cats had aortograms similar to acutely ligated cats. The cinanserin HC1-treated ligation clot-occluded cats had aortograms which indicated hind-limb perfusion was not as adequate as the acutely ligated cats. However, the perfusion of these animals was improved over untreated ligation clot-occluded cats. Neurologic rating correlated with aortograms. These results suggest: 1) the clinical consequences of arterial thrombosis cannot be entirely attributed to mechanical occlusion of an artery, but may be due to depression of protective collateral blood flow induced by thrombosis, 2) serotonin is an important factor in this depression of collateral blood flow, and 3) isolation of the factors responsible for collateral inhibition could permit the development of therapeutic interventions.

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