Numerical Simulation of Flow Distribution and Wall Shear Stress Downstream from an Orifice

2016 ◽  
Vol 2016.21 (0) ◽  
pp. D113
Author(s):  
Shungo MATSUMURA ◽  
Takahiro KIWATA ◽  
Atsusi KAWAI ◽  
Yoichi UTANOHARA ◽  
Takaaki KONO
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Flow Distribution ◽  
Wall Shear

scholarly journals Numerical Simulation of Dispersed Particle-Blood Flow in the Stenosed Coronary Arteries

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Mongkol Kaewbumrung ◽  
Somsak Orankitjaroen ◽  
Pichit Boonkrong ◽  
Buraskorn Nuntadilok ◽  
Benchawan Wiwatanapataphee
Keyword(s):  
Numerical Simulation ◽  
Blood Flow ◽  
Shear Stress ◽  
Coronary Artery ◽  
Pressure Drop ◽  
Wall Shear Stress ◽  
Stokes Equations ◽  
Spherical Shape ◽  
Shear Stresses ◽  
Wall Shear

A mathematical model of dispersed bioparticle-blood flow through the stenosed coronary artery under the pulsatile boundary conditions is proposed. Blood is assumed to be an incompressible non-Newtonian fluid and its flow is considered as turbulence described by the Reynolds-averaged Navier-Stokes equations. Bioparticles are assumed to be spherical shape with the same density as blood, and their translation and rotational motions are governed by Newtonian equations. Impact of particle movement on the blood velocity, the pressure distribution, and the wall shear stress distribution in three different severity degrees of stenosis including 25%, 50%, and 75% are investigated through the numerical simulation using ANSYS 18.2. Increasing degree of stenosis severity results in higher values of the pressure drop and wall shear stresses. The higher level of bioparticle motion directly varies with the pressure drop and wall shear stress. The area of coronary artery with higher density of bioparticles also presents the higher wall shear stress.

Numerical Simulation of Flow-Induced Wall Shear Stress of a One Strand Tundish Design

2011 ◽  
Vol 402 ◽  
pp. 85-89 ◽  
Author(s):  
Zhi Bing Tian ◽  
Yan Jin ◽  
Hong Yu Li
Keyword(s):  
Numerical Simulation ◽  
Mathematical Model ◽  
Shear Stress ◽  
Service Life ◽  
Wall Shear Stress ◽  
Design Parameters ◽  
Horizontal Distance ◽  
Wall Shear

In this paper, the flow-induced wall shear stress on the wall of a one Strand tundish has been computed by a 3-D mathematical model. Different design parameters of the tundish such as HB(the height of the dam) and DB(the horizontal distance between the dam and the outlet of the tundish) are studied by analyzing the flow-induced wall shear stress. After a series of calculation, A modification in design parameters (DB and HB )of the tundish can reduce the wall shear stress, thus may help to improve the service life of the tundish.

Microcirculatory Basis for Nonuniform Flow Delivery with Intravenous Nitroprusside 

1999 ◽  
Vol 91 (3) ◽  
pp. 723-723 ◽  
Author(s):  
Shahzad S. Mustafa ◽  
Richard J. Rivers ◽  
Mary D. S. Frame
Keyword(s):  
Shear Stress ◽  
Mean Arterial Pressure ◽  
Wall Shear Stress ◽  
Arterial Pressure ◽  
Sodium Nitroprusside ◽  
Flow Distribution ◽  
Sprague Dawley ◽  
Wall Shear ◽  
Arteriolar Diameter

Background The purpose of this study was to determine the effects of systemic infusions of nitroglycerin and sodium nitroprusside on flow distribution and wall shear stress in the microcirculation. Methods With university approval, the cremaster muscle of 28 anesthetized (70 mg/kg pentobarbital given intraperitoneally) hamsters (Harlan Sprague Dawley: Syrian; weight, 121+/-11 g [mean +/- SDD) was observed using in vivo fluorescence microscopy. Arteriolar diameter, erythrocyte flux, and velocity were measured for a feed arteriole and its sequential branches. Observations were made during control (mean arterial pressure, 88+/-4 mm Hg) and after 30 min of intravenous delivery of sodium nitroprusside or nitroglycerin, titrated to decrease mean arterial pressure by 20 mm Hg. Results Sodium nitroprusside significantly dilated select upstream portions of the network (23+/-2.6 to 29+/-2.6 microm); no arterioles were dilated with nitroglycerin. Erythrocyte flux into the feed (i.e., inflow into the arteriolar network) and into the sequential branches (i.e., distribution within the network) were evaluated. With nitroglycerin, inflow decreased significantly from 1,560+/-335 to 855+/-171 cells/s, and flux into the branches decreased evenly. With sodium nitroprusside, inflow increased significantly to 2,600+/-918 cells/s, yet cells were "stolen" from upstream branches (a decrease from 425+/-67 to 309+/-87 cells/s in the first branch). Excess flow passed into a downstream "thorough-fare channel," significantly increasing flux from 347+/-111 to 761+/-246 cells/s. Wall shear stress decreased uniformly with nitroglycerin infusion, with a decrease in the feed from 8.8+/-2.5 to 6+/-1.7 dyn/cm2. With sodium nitroprusside, variable changes occurred that were location specific within the network. For instance, at the inflow point to the network, wall shear stress changed from 8.3+/-2.5 to 4.2+/-3.3 dyn/cm2. Conclusions Nitroglycerin infusion promoted homogeneity of flow. Sodium nitroprusside significantly increased the heterogeneity of flow within this arteriolar network; an anatomic location for steal induced by sodium nitroprusside is identified.

Performance Prediction for Optical Wall Shear Stress Sensor Using Direct Numerical Simulation of Fluid Flow

2003 ◽  
Author(s):  
Katsuaki Shirai ◽  
Keisuke Tsuru ◽  
Shinnosuke Obi
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Direct Numerical Simulation ◽  
Performance Prediction ◽  
Stress Sensor ◽  
Doppler Signals ◽  
Shear Stress Sensor ◽  
Wall Shear ◽  
Yaw Angle

We conducted a performance prediction for an optical wall shear stress sensor with using the velocity data of a direct numerical simulation. The Doppler signals were generated with respect to the path of tracer particles passing through the measurement volume. A signal processing technique was proposed to estimate the magnitude and yaw angle of local wall shear stress simultaneously from each Doppler signal. The simulated Doppler signals were processed with the technique, however the accuracy of estimating the yaw angle is not sufficient. In contrast, the estimated magnitude of wall shear stress showed a good agreement with the direct estimate from the DNS data if the yaw angle was accurately estimated. The measurement accuracy of the sensor mainly depends on estimating the yaw angle of each tracer particle. Another technique for detecting the yaw angle is needed for the accurate measurement of both the yaw angle and magnitude of local wall shear stress.

A212 Numerical simulation of Wall Shear Stress Downstream from an Orifice in a Circular Pipe

2014 ◽  
Vol 2014.19 (0) ◽  
pp. 191-192
Author(s):  
Yoichi UTANOHARA ◽  
Junpei NAKAMICHI ◽  
Atsushi KAWAI ◽  
Takahiro KIWATA ◽  
Akira NAKAMURA
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Circular Pipe ◽  
Wall Shear

Numerical simulation of wall shear stress downstream of a headcut

2020 ◽  
pp. 1-33
Author(s):  
Hongyan Wei ◽  
Sean J. Bennett ◽  
Minghui Yu ◽  
Chi Zhou ◽  
Bole Jiang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Wall Shear
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