### Exploration of Wall Thinning Degradation Mechanism in Double Elbow Pipe

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#### Abstract

The objective of this study is to simulate the heavy water flow in the double elbow pipe under flow accelerated corrosion (FAC) conditions. From the simulated results the existence of eddy structures and their mutual interactions are investigated. These eddies are responsible for the wall shear stress distribution and this distribution is an important factor in predicting the local regions of the pipe that are highly susceptible to FAC. The streamline portrait, exhibits the recirculation regions at the corners and at the downstream of the elbows. A detailed study about the reattachment length has been carried out at the preferred recirculation regions, in which the consequences of these regions lead to the high wall shear stress. The calculation of reattachment length and the distribution of wall shear stress, for Re ranging from 1e+2 to 2e+5 are carried out by increasing the distance between the upstream and downstream elbows. It is observed that the reattachment length is initially constant (laminar flow), then increased (transitional flow) and again became constant (turbulent flow) as Re was increased. The reattachment length decreased as the distance between the elbows was increased. The maximum value of wall shear stress occurred in the vicinity of elbows and on the opposite walls of the downstream recirculating regions of elbows. *Copyright © 2013 Praise Worthy Prize - All rights reserved.*

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