Partial filling of porous medium insert in a channel alleviates the tremendous pressure drop associated with a porous medium saturated channel, and enhances heat transfer at an optimum fraction of porous medium filling. This study pioneered an investigation into the viscous dissipative forced convective heat transfer in a parallel-plate channel, partially occupied with a porous medium at the core, under local thermal non-equilibrium condition. Solving the thermal energy equation along the Darcy-Brinkman equation, new exact temperature fields and Nusselt number are presented under symmetrical isoflux thermal boundary condition. Noteworthy is the heat flux bifurcation at the interface between the clear fluid and porous medium driven by viscous dissipation, in cases where the combined hydrodynamic resistance to fluid flow and thermal resistance to fluid conduction is considerable in low Darcy number porous medium insert. However, viscous dissipation does not affect the qualitative variation of the Nusselt number with the fraction of porous medium filling. By using Al2O3-Water nanofluid as the working fluid in a uniformly heated microchannel, partially filled with an optimum volume fraction of porous medium, the heat transfer coefficient improves as compared to utilizing water. The accompanied viscous dissipation however has a more adverse impact on the heat transfer coefficient of nanofluids with an increasing Reynolds number.
Welding is a crucial process in joining metals, especially in the fabrication industry. Thisresearch aimed to investigate the effects of using two different filler materials, ER70S-6 and ER308LSi, with nine combinations of wire feeder speed (WFS) and shielding gas flow rate (GFR), on weld joints. The study focused on the weld quality and material properties of Gas Metal Arc Welded (GMAW) butt joints of ASTM A516 G70 plates, characterized through visual inspection, liquid penetrant testing, tensile testing, hardness testing, and optical microscopy. Results indicated that the highest ultimate tensile strength and hardness were achieved at 4 m/min WFS and 15 L/min GFR with ER70S-6, and 5 m/min WFS and 20 L/min GFR with ER308LSi. The specimens welded with ER308LSi demonstrated superior mechanical properties compared to those welded with ER70S-6. Additionally, the study revealed the influence of microstructural changes from the base metal (BM) to the heat-affected zone (HAZ) and fusion zone (FZ), with finer and more compact grain structures contributing to higher hardness values. These findings underscore the importance of selecting appropriate filler materials, WFS, and GFR to achieve the desired weld quality and material properties for A516 G70 low-carbon steel welded joints.