Mechanical Engineering
Graduate Seminar
NOTICE OF SEMINAR PRESENTATION
CANDIDATE: Nicolas Kelly
DEGREE SOUGHT: MASc
DATE: 5/22/2026
TIME: 11:30am
PLACE: Room 1101 CEI
TITLE: Effect of Hemi-Spherical Protrusions on Rectangular Channel Flow and Cooling Characteristics
Abstract
Using spanwise hemi-spherical protrusions aligned concentrically with Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) chips, turbulent fluid flow can help enhance the heat transfer between the chips and the given fluid. Within a non-circular duct, the Reynolds stresses within the fluid induce secondary currents at the intersection of the inner walls. These secondary currents create additional turbulence that propagates downstream. Understanding the effect between hemi-spherical protrusions and secondary currents is beneficial for cooling MOSFET chips and other electrical components alike. Initial work was completed on a flat plate in an open channel for visualization and understanding of the underlying structures surrounding the hemisphere. An unsteady, three-dimensional, incompressible Large Eddy Simulation (LES) was employed to capture secondary currents. Experimental results were completed in a large recirculating water channel to validate numerical results. The Reynolds number based on the bulk mean velocity and the diameter of the hemisphere ( ) is 8160. Preliminary results suggest that the increase in turbulent mixing provided by the protrusions and secondary currents increases the heat transfer between electronics and the fluid. The protrusion creates a horseshoe vortex which, dependent on the aspect ratio of the duct and the diameter of the protrusion, interacts with the secondary currents in the duct and enhances turbulent mixing. Further work will study the rectangular duct and its effects on the hemi-spherical protrusion’s structures, as well as the heat transfer characteristics with a MOSFET chip