Hemodynamic Patterns in Two Models of End-to-Side Vascular Graft Anastomoses: Effects of Pulsatility, Flow Division, Reynolds Number, and Hood Length

1993 ◽  
Vol 115 (1) ◽  
pp. 104-111 ◽  
Author(s):  
S. S. White ◽  
C. K. Zarins ◽  
D. P. Giddens ◽  
H. Bassiouny ◽  
F. Loth ◽  
...  
Keyword(s):  
Residence Time ◽  
Vascular Graft ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Canine Model ◽  
Video Tape ◽  
Intimal Thickening ◽  
Particle Residence Time ◽  
Wall Shear

Flow behavior in models of end-to-side vascular graft anastomoses was studied under steady and pulsatile flow conditions. Models were constructed to simulate geometries employed in experimental studies on intimal thickening in a canine model. Reynolds numbers, division of flow in the outflow tracts and the pulsatile waveform employed were taken from measurements obtained in the canine model. Flows in the scaled-up, transparent models were visualized with white, neutrally buoyant particles which were photographed under laser illumination and also recorded on video tape under bright incandescent light. Strong, three-dimensional helical patterns which formed in the anastomotic junction were prominent features of the flow fields. Regions of low wall shear, oscillatory wall shear and long particle residence time were identified from the flow visualization experiments. Comparisons with the limited qualitative data available on intimal thickening in vascular graft anastomoses suggest a relation between localization of vascular intimal thickening and those surfaces experiencing low shear and long particle residence time.

scholarly journals Investigation of Flow Behavior around Corotating Blades in a Double-Spindle Lawn Mower Deck

2005 ◽  
Vol 2005 (1) ◽  
pp. 77-89 ◽  
Author(s):  
W. Chon ◽  
R. S. Amano
Keyword(s):  
Flow Pattern ◽  
High Speed ◽  
Flow Behavior ◽  
Flow Analysis ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Video Camera ◽  
Sound Level ◽  
Lawn Mower ◽  
Level Meter

When the airflow patterns inside a lawn mower deck are understood, the deck can be redesigned to be efficient and have an increased cutting ability. To learn more, a combination of computational and experimental studies was performed to investigate the effects of blade and housing designs on a flow pattern inside a1.1mwide corotating double-spindle lawn mower deck with side discharge. For the experimental portion of the study, air velocities inside the deck were measured using a laser Doppler velocimetry (LDV) system. A high-speed video camera was used to observe the flow pattern. Furthermore, noise levels were measured using a sound level meter. For the computational fluid dynamics (CFD) work, several arbitrary radial sections of a two-dimensional blade were selected to study flow computations. A three-dimensional, full deck model was also developed for realistic flow analysis. The computational results were then compared with the experimental results.

scholarly journals Analysis of Hydrodynamics of Fluid Flow on Corrugated Sheets of Packing

2012 ◽  
Vol 2012 ◽  
pp. 1-13 ◽  
Author(s):  
Kumar Subramanian ◽  
Günter Wozny
Keyword(s):  
Flow Behavior ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Elementary Geometry ◽  
Ansys Fluent ◽  
Vof Model ◽  
Corrugated Sheets ◽  
Wetted Area ◽  
Icem Cfd ◽  
Good Agreement

Modelling of the hydrodynamics behaviour of the liquid on the corrugated sheets of packing is studied using three-dimensional, volume-of-fluid (VOF) model that is incorporated in Ansys Fluent 12.0. The flow of three different liquids with different physical properties is modelled. A domain of corrugated sheets of packing resembling the real structured packing with little modifications in the elementary geometry is constructed using ICEM CFD 12.0. The quantitative comparisons of the wetting behavior from the simulations are in good agreement with experiments. Further, the study has been extended to understand the influence of the second corrugated sheet on the flow behavior. The contours from the simulations indicate the liquid hold-up in the crimp of two corrugated sheets, and these results are in good agreement with the earlier experimental studies performed using X-ray tomography in the literature. The result from the simulation shows that even for the high flow rate of around 811 mL/min for silicon-oil (DC5), only 60% of the corrugated sheet has been wetted. Hence, the efficiency of the existing packing can be further increased by increasing the wetted area in the corrugated sheet of packing.

Suspension flow behavior and particle residence time distribution in helical tube devices

2019 ◽  
Vol 360 ◽  
pp. 1371-1389 ◽  
Author(s):  
Lukas Hohmann ◽  
Mira Schmalenberg ◽  
Mathusah Prasanna ◽  
Martin Matuschek ◽  
Norbert Kockmann
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Flow Behavior ◽  
Suspension Flow ◽  
Particle Residence Time ◽  
Helical Tube

Experimental and Numerical Investigation of the Flow Behavior in a Tapered Rectangular Sprue

2002 ◽  
Author(s):  
Abdessalem Derdouri ◽  
Florin Ilinca ◽  
Kalonji Kabanemi ◽  
Jean-Franc¸ois He´tu
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Pressure Sensors ◽  
Reinforced Polymers ◽  
Volumetric Rate ◽  
Wall Shear ◽  
Dimensional Simulation ◽  
Large Width

The present study is part of a continuing effort to obtain a better understanding of the rheological behavior during the injection molding of unfilled and reinforced polymers and help improve the prediction by numerical three dimensional simulation of the process. The slightly tapered rectangular sprue of a centrally gated plaque mold was equipped with flush mounted pressure sensors to monitor the time evolution of the wall shear stress prior to entering the cavity. Two Polycarbonate with different zero-shear rate viscosities were tested at various injection speeds. Atter an initial rise, the wall shear stress in the sprue remains constant during the filling stage of the mold. The transient shear viscosity was determined from the known volumetric rate using a simplified one-dimensional flow approach and compared to the viscosity measured by traditional off-line rheometers. A finite element three-dimensional code is used to simulate the flow in the sprue with small and large width over thickness ratios. The pressures predicted are used in combination with the simplified theory to calculate the viscosity and compare the results from the experiments.

scholarly journals CFD Simulation of Local Scouring Around Bridge Pier

2019 ◽  
Vol 9 (1) ◽  
pp. 1870-1880
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Local Scour ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Multiphase Model ◽  
Model Studies ◽  
Dimensional Simulation

The threat of local scour around bridge piers has been in research for many years. According to the various studies, local scour around the bridge pier is the prime cause for most of the bridge failures. The main objective of the present study was to investigate the flow behavior and the scour phenomenon around the bridge piers of various shapes namely Circular, Elliptical, Square and Streamlined. Local scouring depends on various factors like depth of flow, upstream flow conditions, pier shape and dimensions. Here, we have taken only pier shape as the primary factor and kept other factors constant. The numerical simulations were even carried out using CFDFluent, Eulerian multiphase model, k–epsilon turbulence model, to elaborate the physics behind the scour formation. CFD simulation tool can be used for wide understanding of the flow behavior around the bridge piers even without physical model studies because it saves time and money as compared to experimental studies. Three dimensional simulation of flow behavior around four pier shapes indicates that the streamlined pier is the most efficient pier to use as it allows the flow to pass smoothly around it creating less obstruction to the flow and hence creating less chances of local scouring near the pier toe.

scholarly journals Targeting hepatocyte growth factor in epithelial–stromal interactions in an in vitro experimental model of human periodontitis

Odontology ◽  
2021 ◽  
Author(s):  
Yoko Yamaguchi ◽  
Akira Saito ◽  
Masafumi Horie ◽  
Akira Aoki ◽  
Patrick Micke ◽  
...  
Keyword(s):  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Collagen Gel ◽  
Neutralizing Antibody ◽  
Chronic Inflammatory Disease ◽  
Collagen Degradation ◽  
Hepatocyte Growth

AbstractPeriodontitis is a chronic inflammatory disease leading to progressive connective tissue degradation and loss of the tooth-supporting bone. Clinical and experimental studies suggest that hepatocyte growth factor (HGF) is involved in the dysregulated fibroblast–epithelial cell interactions in periodontitis. The aim of this study was to explore effects of HGF to impact fibroblast-induced collagen degradation. A patient-derived experimental cell culture model of periodontitis was applied. Primary human epithelial cells and fibroblasts isolated from periodontitis-affected gingiva were co-cultured in a three-dimensional collagen gel. The effects of HGF neutralizing antibody on collagen gel degradation were tested and transcriptome analyses were performed. HGF neutralizing antibody attenuated collagen degradation and elicited expression changes of genes related to extracellular matrix (ECM) and cell adhesion, indicating that HGF signaling inhibition leads to extensive impact on cell–cell and cell–ECM interactions. Our study highlights a potential role of HGF in periodontitis. Antagonizing HGF signaling by a neutralizing antibody may represent a novel approach for periodontitis treatment.

Computational and Experimental Study of Enhanced Laminar Flow Heat Transfer in Three-Dimensional Sinusoidal Wavy-Plate-Fin Channels

2003 ◽  
Author(s):  
Jiehai Zhang ◽  
Arun Muley ◽  
Joseph B. Borghese ◽  
Raj M. Manglik
Keyword(s):  
Heat Transfer ◽  
Flow Behavior ◽  
Computational Simulation ◽  
Three Dimensional ◽  
Heat Fluxes ◽  
Staggered Grid ◽  
Uniform Heat Flux ◽  
Complex Flow ◽  
Constant Property ◽  
Fin Efficiency

Enhanced heat transfer characteristics of low Reynolds number airflows in three-dimensional sinusoidal wavy plate-fin channels are investigated. For the computational simulation, steady state, constant property, periodically developed, laminar forced convection is considered with the channel surface at the uniform heat flux condition; the wavy-fin is modeled by its two asymptotic limits of 100% and zero fin efficiency. The governing equations are solved numerically using finite-volume techniques for a non-orthogonal, non-staggered grid. Computational results for velocity and temperature distribution, isothermal Fanning friction factor f and Colburn factor j are presented for airflow rates in the range of 10 ≤ Re ≤ 1500. The numerical results are further compared with experimental data, with excellent agreement, for two different wavy-fin geometries. The influence of fin density on the flow behavior and the enhanced convection heat transfer are highlighted. Depending on the flow rate, a complex flow structure is observed, which is characterized by the generation, spatial growth and dissipation of vortices in the trough region of the wavy channel. The thermal boundary layers on the fin surface are periodically disrupted, resulting in high local heat fluxes. The overall heat transfer performance is improved considerably, compared to the straight channel with the same cross-section, with a relatively smaller increase in the associated pressure drop penalty.

scholarly journals Numerical and Experimental Studies on a Three-Dimensional Numerical Wave Tank

IEEE Access ◽  
2018 ◽  
Vol 6 ◽  
pp. 6585-6593 ◽  
Author(s):  
Xiaojie Tian ◽  
Qingyang Wang ◽  
Guijie Liu ◽  
Wei Deng ◽  
Zhiming Gao
Keyword(s):  
Experimental Studies ◽  
Three Dimensional ◽  
Numerical Wave Tank ◽  
Wave Tank ◽  
Numerical Wave
Sign in / Sign up

Export Citation Format

Share Document