Salman, Yasin, and Hussein Mohammed. “Free Convective Heat Transfer With Different Sections Lengths Placed at the Exit of a Vertical Circular Tube Subjected to a Constant Heat Flux”. Al-Khwarizmi Engineering Journal 3, no. 3 (September 1, 2007): 31-52. Accessed November 21, 2019. http://alkej.uobaghdad.edu.iq/index.php/alkej/article/view/631.