Conference Agenda

Thermal fatigue caused by fluid mixing and thermal stratification is a common degradation mechanism in industrial piping systems, including chemical, process, and energy-generation applications such as nuclear power plants. Stagnant or low-flow branch lines are particularly susceptible due to the interaction between the flowing fluid in the main pipe and the stagnant fluid in the branch, creating fluctuating thermal interfaces and cyclic thermal stresses that may ultimately lead to structural degradation and failure. This presentation reviews the current understanding of flow and thermal-hydraulic phenomena occurring in dead-ended branch lines based on recent high-resolution experimental investigations, large-scale CFD benchmark activities, and complementary in-house studies. Particular attention is given to the evolution of cavity flow, the development of secondary flow structures and swirl, thermal penetration into the branch line, and the formation of stratified thermal layers. Insights obtained from dedicated separate-effect experiments and integral test facilities are discussed to improve understanding of the governing physical mechanisms. The capabilities of modern CFD approaches for predicting these complex flow and thermal phenomena are evaluated using results from recent international benchmark studies. The presentation summarizes the key mechanisms governing thermal fatigue loading, assesses the current state of predictive tools, and identifies remaining challenges for the reliable analysis and management of thermally stratified branch-line systems.