TY - JOUR AU - Kamiyo, Ola PY - 2022/04/02 Y2 - 2024/03/29 TI - ANA LYSIS OF THE FLOW AND THERMAL FIELDS IN BOBTAIL ROOFS HEATED FROM THE BASE WALL JF - THE IRAQI JOURNAL FOR MECHANICAL AND MATERIALS ENGINEERING JA - IQJMME VL - 22 IS - 1 SE - Articles DO - 10.32852/iqjfmme.v22i1.581 UR - https://www.iqjfmme.com/index.php/jmme/article/view/581 SP - 1-15 AB - <p>Analysis of airflow and thermal characteristics of attics of bobtail-shaped pitched roofs heated <br>through a horizontally suspended ceiling is numerically carried out in this study. Pitch angles <br>of 14o, 18o, 30o, and 45o within the standard pitch roof range are selected. The configuration <br>falls within Rayleigh number 3.19 x 105  Ra  2.04 x 107. A finite-volume CFD code was <br>used to solve the mass, momentum, and energy conservation equations governing the <br>problem. The results obtained indicate a strong influence on the shape and angle of the roof. <br>At lower roof pitches, the flow field is characterized by multiple counter-rotating vortices <br>asymmetrically arranged within the enclosures. Eight cells in the 14o enclosure were reduced <br>to five in the 45o roof pitch. The size and rotating strength of a vortex increase from the left <br>corner to the middle of the enclosures. At higher pitch angles, the vertical wall obstructed the <br>flow leading to a number of distorted cells. The maximum velocity within the aerodynamic <br>boundary layer along the base wall occurs at Y=0.02 with the values U=0.013 and U=0.028 <br>in the 14o and 45o enclosures respectively. The thermal field portrays a convection system of <br>rising hot plumes from the base wall and descending cold jets from the inclined walls; all <br>enclosed by thin boundary layers along the walls. Graphical plots of velocity and temperature <br>variations along some cross-sections within the enclosures enable the prediction of some <br>important heat and flow parameters.</p><p>&nbsp;</p> ER -