Laminar velocity profile development in straight pipes of circular cross section

1968 ◽  
Vol 7 (3) ◽  
pp. 286-289 ◽  
Author(s):  
M. P. Brocklebank ◽  
J. M. Smith
Author(s):  
Boualem Laribi ◽  
Abdelkader Youcefi ◽  
Elhacene Matene

This article presents a numerical investigation of the development and the establishment of the flow in the presence of the Etoile flow straightener recommended in ISO 5167 (ISO 5167. Measurement of fluid flow by means of orifice plates, nozzles and venture plates inserted in circular cross-section conduits running full, 2003). The objective of this study is to examine the effectiveness length of the Etoile flow straightener, recommended by ISO 5167 with length of two pipe diameters, on the development and the establishment of the flow. The flow is produced by air in a 100mm pipe diameter and 40D of length with a Reynolds number of 2.5×105. The disturbance is a valve maintained at 100% and 50% open. The flow parameters examined are velocity profile, turbulence intensity profile, and the gyration of the fluid. Several measuring stations upstream and downstream of the unit are done. The code CFD Fluent is used for this simulation. The results obtained are compared according to directives of the standard ISO 5167. However, they show that for position valve 100% open the various lengths of the Etoile flow straightener do not present differences for the three flow parameters. On the other hand, for the valve position 50% open, the Etoile flow straightener with 2D length which presents the best performances according the standard.


2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Mehran Khaki Jamei ◽  
Mohsen Heydari Alashti ◽  
Morteza Abbasi ◽  
Aliosat EbrahimNejad ◽  
Mohammad Hasan Taheri

AbstractThe present study aims to investigate the effect of the round edge on the laminar Newtonian fluid that flows through a channel. As an innovation, the sine and cosine transform functions are employed to solve the momentum governing equation in Cartesian and Cylindrical coordinates. Owing to the duct symmetric, only the quarter of the cross-section (θ = 0 to π/2) is analyzed. The analytical correlations for velocity distribution in both coordinates are provided; afterward, the effect of the round edge on the velocity profile has been investigated. It can be concluded that if a circular cross-section is replaced with a non-circular cross-section, the velocity profile becomes more uniform and less velocity variation is observed. Further, with a constant pressure gradient, among rectangular, round edge and circular cross-sections, the maximum velocity in a circular cross-section becomes minimum. In addition, it is observed that for the same pressure difference, an increase of m value leads to the higher average velocity and mass flow.


2018 ◽  
Vol 14 (1) ◽  
pp. 1
Author(s):  
Prof. Dr. Jamal Aziz Mehdi

The biological objectives of root canal treatment have not changed over the recentdecades, but the methods to attain these goals have been greatly modified. Theintroduction of NiTi rotary files represents a major leap in the development ofendodontic instruments, with a wide variety of sophisticated instruments presentlyavailable (1, 2).Whatever their modification or improvement, all of these instruments have onething in common: they consist of a metal core with some type of rotating blade thatmachines the canal with a circular motion using flutes to carry the dentin chips anddebris coronally. Consequently, all rotary NiTi files will machine the root canal to acylindrical bore with a circular cross-section if the clinician applies them in a strictboring manner


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