Laminar viscous flow through pipes, related to cross-sectional area and perimeter length

2019 ◽  
Vol 87 (10) ◽  
pp. 791-795 ◽  
Author(s):  
John Lekner
Keyword(s):  
Viscous Flow ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Area And Perimeter ◽  
Flow Through

Effect of Tapering on Pulsatile Flow Through a U-Tube Model of the Human Aortic Arch

2010 ◽  
Author(s):  
Masaru Sumida
Keyword(s):  
Velocity Profile ◽  
Pulsatile Flow ◽  
Velocity Profiles ◽  
Cross Sectional Area ◽  
Flow Rate Ratio ◽  
Sectional Area ◽  
Cross Sectional ◽  
Turn Angle ◽  
Flow Through ◽  
The Cross

An experimental investigation of pulsatile flow through a tapered U-tube was performed to study the blood flow in the aorta. The experiments were carried out in a U-tube with a curvature radius ratio of 3.5 and a 50% reduction in the cross-sectional area from the entrance to the exit of the curved section. Velocity measurements were conducted by a laser Doppler velocimetry for a Womersley number of 10, a mean Dean number of 400 and a flow rate ratio of 1. The velocity profiles for pulsatile flow in the tapered U-tube were compared with the corresponding results in a U-tube having a uniform cross-sectional area. The striking effects of the tapering on the flow are exhibited in the axial velocity profiles in the section from the latter half of the bend to the downstream tangent immediately behind the bend exit. A depression in the velocity profile appears at a smaller turn angle Ω in the case of tapering, although the magnitude of the depression relative to the cross-sectional average velocity decreases. The value of β, which indicates the uniformity in the velocity profile over the cross section, decreases with increasing Ω, whereas it rapidly increases immediately behind the bend exit.

Identification of the piston machine combustion chamber tightness

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Piotr Jan Bielawski
Keyword(s):  
Combustion Chamber ◽  
Measurement System ◽  
Gas Flow ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Content Type ◽  
Flow Through ◽  
The Cross ◽  
Pneumatic Sensor

PurposeThe lack of integrity of the piston machine combustion chamber manifests itself in leakages of the working fluid between the piston and the cylinder liner, at valves mounted in the cylinder head and between the head and the liner. An untight combustion chamber leads to decreased power output or efficiency of the engine, while leaks of a fluid may cause damage to many components of the chamber. The actual value of working chamber leak is a desired and essential piece of information for planning operations of a given machine.Design/methodology/approachThis research paper describes causes and mechanisms of leakage from the working chamber of internal combustion engines. Besides, the paper outlines presently used methods and means of leak identification and states that their further development and improvements are needed. New methods and their applicability are presented.FindingsThe methods of leak identification have been divided into diagnostic and non-working machine leak identification methods. The need has been justified for the identification of leakage from the combustion chamber of a non-working machine and for using the leakage measure as the value of the cross-sectional area of the equivalent leak, defined as the sum of cross-section areas of all leaking paths. The analysis of possible developments of tightness assessment methods referring to the combustion chamber of a non-working machine consisted in modelling subsequent combustion chamber leaks as gas-filled tank leak, leak from another element of gas-filled tank and as a regulator of gas flow through a nozzle.Originality/valueA measurement system was built allowing the measurement of pressure drop in a tank with the connected engine combustion chamber, which indicated the usefulness of the system for leakage measurement in units as defined in applicable standards. A pneumatic sensor was built for measuring the cross-sectional area of the equivalent leak of the combustion chamber connected to the sensor where the chamber functioned as a regulator of gas flow through the sensor nozzle. It has been shown that the sensor can be calibrated by means of reference leaks implemented as nozzles of specific diameters and lengths. The schematic diagram of a system for measuring the combustion chamber leakage and a diagram of a sensor for measuring the cross-sectional area of the equivalent leak of the combustion chamber leakage are presented. The results are given of tightness tests of a small one-cylinder combustion engine conducted by means of the set up measurement system and a pre-prototype pneumatic sensor. The two solutions proved to be practically useful.

scholarly journals The African Origin of Complex Projectile Technology: An Analysis Using Tip Cross-Sectional Area and Perimeter

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Matthew L. Sisk ◽  
John J. Shea
Keyword(s):  
Middle Stone Age ◽  
Cross Sectional Area ◽  
Stone Age ◽  
Sectional Area ◽  
African Origin ◽  
Cross Sectional ◽  
Projectile Points ◽  
Projectile Technology ◽  
Area And Perimeter ◽  
Point Types

Despite a body of literature focusing on the functionality of modern and stylistically distinct projectile points, comparatively little attention has been paid to quantifying the functionality of the early stages of projectile use. Previous work identified a simple ballistics measure, the Tip Cross-Sectional Area, as a way of determining if a given class of stone points could have served as effective projectile armatures. Here we use this in combination with an alternate measure, the Tip Cross-Sectional Perimeter, a more accurate proxy of the force needed to penetrate a target to a lethal depth. The current study discusses this measure and uses it to analyze a collection of measurements from African Middle Stone Age pointed stone artifacts. Several point types that were rejected in previous studies are statistically indistinguishable from ethnographic projectile points using this new measure. The ramifications of this finding for a Middle Stone Age origin of complex projectile technology is discussed.

Kinematic description of fluids in motion and approximations

2018 ◽  
Author(s):  
Marcel Escudier
Keyword(s):  
Fluid Velocity ◽  
Slip Boundary Condition ◽  
Cross Sectional Area ◽  
Constant Density ◽  
Sectional Area ◽  
Cross Sectional ◽  
Slip Boundary ◽  
Flow Problems ◽  
Mass Flowrate ◽  
Flow Through

In this chapter some of the terminology and simplifications which enable us to begin to describe and analyse practical fluid-flow problems are introduced. The terms ‘fluid particle’ and ‘streamline’ are defined. The principle of conservation of mass applied to steady one-dimensional flow through a streamtube of varying cross-sectional area resulted in the continuity equation. This important equation relates mass flowrate ṁ, volumetric flowrate Q̇, average fluid velocity V̄, fluid density ρ‎, and cross-sectional area A: m = ρ‎ Q̇ = ρ‎AV̅ = constant. For a constant-density fluid this result shows that fluid velocity increases if the cross-sectional area decreases, and vice versa. The no-slip boundary condition, a consequence of which is the boundary layer, is introduced.

scholarly journals EXPERIMENTAL AND NUMERICAL STUDIES ON WATER FLOW THROUGH RECTANGULAR CROSS-SECTIONAL AREA S-SHAPED DIFFUSERS

2015 ◽  
Vol 38 (4) ◽  
pp. 309-325
Author(s):  
K. A Ibrahim ◽  
W. A El-Askary ◽  
I. M Sakr ◽  
Hamdy A Omara
Keyword(s):  
Water Flow ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Numerical Studies ◽  
Flow Through

scholarly journals Potential Applications of Computational Fluid Dynamics for Predicting Hemolysis in Mitral Paravalvular Leaks

2021 ◽  
Vol 10 (24) ◽  
pp. 5752
Author(s):  
Michał Kozłowski ◽  
Krzysztof Wojtas ◽  
Wojciech Orciuch ◽  
Marek Jędrzejek ◽  
Grzegorz Smolka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Ansys Fluent ◽  
Potential Applications ◽  
Fluent Software ◽  
Flow Through

Paravalvular leaks (PVLs) may lead to hemolysis. In vitro shear stress forces above 300 Pa cause erythrocyte destruction. PVL channel dimensions may determine magnitude of shear stress forces that affect erythrocytes; however, this has not been tested. It remains unclear how different properties of PVL channels contribute to presence of hemolysis. A model of a left ventricle was created based on data from computer tomography with Slicer software PVLs of various shapes and sizes were introduced. Blood flow was simulated using ANSYS Fluent software. The following variables were examined: wall shear stress, shear stress in fluid, volume of PVL channel with shear stress exceeding 300 Pa, and duration of exposure of erythrocytes to shear stress values above 300 Pa. In all models, shear stress forces exceeded 300 Pa. Shear stress increased with blood flow rates and cross-sectional areas of any PVL. There was no linear relationship between cross-sectional area of a PVL and volume of a PVL channel with shear stress > 300 Pa. Blood flow through mitral PVLs is associated with shear stress above 300 Pa. Cross-sectional area of a PVL does not correlate with volume of a PVL channel with shear stress > 300 Pa and duration of exposure of erythrocytes to shear stress > 300 Pa.

scholarly journals Vaginal Thickness, Cross-Sectional Area, and Perimeter in Women With and Those Without Prolapse

2005 ◽  
Vol 105 (5, Part 1) ◽  
pp. 1012-1017 ◽  
Author(s):  
Yvonne Hsu ◽  
Luyun Chen ◽  
John O. L. Delancey ◽  
James A. Ashton-Miller
Keyword(s):  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Area And Perimeter

scholarly journals Drainage Performance of a Novel Catheter Designed to Reduce Drainage Catheter Failure

2020 ◽  
Vol 4 (01) ◽  
pp. 09-15
Author(s):  
Muath Bishawi ◽  
Bradley Feiger ◽  
Neel Kurupassery ◽  
Konstantinos Economopoulos ◽  
Paul Suhocki ◽  
...  
Keyword(s):  
Flow Rate ◽  
Cross Sectional Area ◽  
Surrounding Tissue ◽  
Sectional Area ◽  
Cross Sectional ◽  
Side Hole ◽  
Hole Shape ◽  
Drainage Catheter ◽  
Catheter Design ◽  
Flow Through

Abstract Objective Efficient flow of fluids through drainage/infusion catheters is affected by surrounding tissue, organ compression, and scar tissue development, limiting or completely obstructing flow through drainage holes. In this work, we introduce a novel three-dimensional (3D) drainage catheter with protected side holes to reduce flow blockages. We then compare its drainage performance to standard straight and pigtail catheters using computer-generated catheter designs and flow analysis software. Methods Drainage performance was computed as flow rate through the catheter for a given pressure differential. Each catheter contained drainage holes on the distal (insertion) end and a single outlet (hub) hole open to atmosphere. Computational fluid dynamics using ANSYS AIM 18.2 was used to simulate flow through the catheter and examine drainage performance based on variations to the following parameters: (1) side hole shape, (2) cross-sectional area of the catheters, (3) number of side holes, and (4) cross-sectional area of the side holes. Results Drainage through the newly introduced catheter in all simulations was nearly identical to standard pigtail and straight catheters. While working to optimize the 3D catheter design, we found that the changes in side hole shape and side hole cross-sectional area had little effect on the total flow rate through the catheters but had a large impact on flow rate through the side hole nearest to the hub (proximal hole). Additionally, the majority of flow in all catheters occurred at the most proximal 1 to 3 side holes closest to hub, with relatively little flow occurring at side holes more distally located (closest to insertion end). The 3D catheter demonstrated no changes in flow characteristics when the coiled segment was occluded, giving it an advantage over other catheter types when the catheter is compressed by surrounding tissue or other external obstruction. Conclusions The majority of fluid flow in catheters with a diameter of 4.67 mm (14 Fr) or smaller occurred at the most proximal 1 to 3 side holes. A novel 3D coiled catheter design can protect these proximal holes from external blockage while maintaining drainage performance compared with standard straight and pigtail catheters.

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