In this study, numerical investigation was carried out on combined free and forced convection for transition flow of water in a conduit that has a mechanical component, which is a three-sided-polygon-perforations-tranverse-axes tape, inserted in its interior. The purpose of the investigation is to find out the thermo-hydraulic characteristics of mixed convection of transition flow in the tube, and compare them with those of forced convection. Fluent software was used to perform the numerical investigation for the transition flow at Reynolds number (Re) in the range 2,150≤Re≤3,700 for the tube bent at sundry tilts (λ) in the range〖 15〗^o≤λ≤〖 90〗^o. The results indicated that the inside temperature and surface temperature of the tube whose fluid flow is forced convection are lower than the case of the tube whose fluid flow is mixed convection, and that the temperatures (tube’s inside temperature, dimensionless outlet temperature, and surface temperature) increase as the tube tilt increases. Not only that, as the tube tilt increases, the dimensionless outlet temperature increases, but the outlet velocity decreases. The Nusselt number in the tube whose fluid flow is forced convection is lower than the case of mixed convection. For the tube with flow tilts of 15^o,30^o,〖 60〗^o, and 90^o, the Nusselt number are 4.01 to 6.10%, 4.60 to 7.41%, 5.32 to 8.71%, and 6.31 to 10.12%, respectively, greater than the case of the tube whose fluid flow is forced convection, for the Reynolds number considered. The validation of the numerical work with an experimental work confirms the correctness of the numerical work.