Eman Elsheikh, Nurah Alkhteeb, Aisha Alamer, Maryam O Alarfaj, Ghaida AlQarni, Jumana Alsultan
Medical Students' Competency and Confidence in Interpreting Electrocardiograms at King Faisal University, Al-Ahsa
Cureus
study investigates gasliquid twophase countercurrent flow vertical annulus phenomenon prevalent across numerous industrial fields presence inner pipe varying degrees eccentricity inner outer pipes often blur clear demarcation flow regime boundaries address designed vertical annulus adjustable eccentricity outer inner diameters 125 mm 75 mm respectively conducted gasliquid countercurrent flow experiments specific conditions gas superficial velocity ranging 006 504 ms liquid superficial velocity 001 025 ms five levels eccentricity e 0 025 05 075 1 collected differential pressure data two distinct height distances dp1 50 mm dp2 1000 mm used vectors composed probability density functions pdfs differential pressure signals power spectral density psd reduced via principal component analysis features using cfdp clustering algorithmbased local densitywe clustered flow regimes experimental data thereby achieving objective consistent identification flow regime gasliquid twophase countercurrent flow vertical annulus analysis reveals dp1 main differences psd various flow regimes occur within 051 hz range among three flow regimes involved slug flow exhibits highest power intensity followed bubbly flow churn flow least terms differential pressure distribution bubbly churn flows concentrated distribution slug flow dispersed dp2 psd differences primarily exist within 052 hz range churn flow highest power intensity followed slug flow bubbly flow weakest bubbly flows differential pressure distribution concentrated slug churn flows dispersed based results flow regime classification generated flow regime map analyzed influence annulus eccentricity flow regime found cases pipe eccentricity significantly affect flow regime however transition regionsuch bubbly slug flow transition zoneflows medium eccentricity values e 05 075 likely transition slug flow compared visual recognition results flow regimes clustering results 404 total samples showed different results visual recognition clustering primarily located flow regime transition area since visually distinguishing flow regimes areas typically challenging methodology offers objective classification approach gasliquid twophase countercurrent flow vertical annulus