Forced convection heat transfer from an unconfined permeable/porous semi-circular cylinder has been studied in the current work for the various governing parameters as Darcy number (Da), Reynolds number (Re) and porosity (ε): The range of these governing parameters has been taken as 10⁻⁶ ≤ Da ≤ 10⁻¹; 1 ≤ Re ≤ 30 and porosity ε = 0:5 because the considered ranges of these parameters have many implementations in flow through blood clots, geophysics and marine related applications etc. The flow within the permeable cylinder is administrated by the Darcy-Brinkman-Forchheimer (D-B-F) model. The thermal field has been analyzed by isotherm contours, local Nusselt number (Nu_L) and average Nusselt number (Nu_avg): The local Nusselt number is observed to increase with Da at the front curved surface of the permeable cylinder but it diminishes with Da at the rear straight surface of the cylinder. The average Nusselt number (Nu_avg) is magnified with the enhancement in Re and Da. Overall, the combined influences of all the governing parameters have been examined in the current study.