技術論文とプレゼンテーション

Efficient thermal management in compact high-heat-flux systems requires cooling methods that enhance convective heat transfer while limiting additional flow resistance. This study uses COMSOL Multiphysics to investigate transient forced convection in a long straight channel containing an oscillating adiabatic blade. The main objective is to quantify how the initial blade orientation, horizontal or vertical, affects vortex formation, heat-transfer performance, and pressure drop under laminar flow conditions. The model considers a two-dimensional incompressible flow in a channel of length 31D and height 3D, with constant heat flux applied at the upper and lower walls, a cold inlet, and an open outlet. The blade is placed near the inlet region and prescribed with sinusoidal oscillatory motion. Simulations are performed at Reynolds number Re = 50 and Prandtl number Pr = 1, while varying nondimensional maximum blade velocity, Vm = 0.5, 1.0, and 2.0, and oscillation frequency, Fc = 0.2, 0.5, and 0.8. The moving-boundary problem is solved using the Arbitrary Lagrangian-Eulerian finite element formulation in COMSOL Multiphysics. This approach enables the computational mesh to deform with the blade motion while the coupled Navier-Stokes and energy equations are solved over the time-dependent domain. A grid independence study is performed, and the final meshes contain 126,400 elements for the horizontal-blade case and 127,890 elements for the vertical-blade case. The model is also validated against previously published oscillating-blade heat-transfer results, showing close agreement in both average Nusselt number and pressure-drop predictions. The results show that the vertical blade creates stronger flow disturbance, larger recirculation regions, and improved thermal mixing compared with the horizontal blade. The highest heat-transfer performance occurs for the vertically oriented blade at Vm = 1.0 and Fc = 0.8, giving approximately 12.35% higher thermal performance than the weakest case, which occurs for the horizontally oriented blade at Vm = 0.5 and Fc = 0.8. However, this enhancement comes with a clear hydraulic penalty. The maximum average pressure drop also occurs for the vertical blade at Vm = 1.0 and Fc = 0.8, approximately 73.80% higher than the minimum pressure-drop condition. Overall, the COMSOL-based ALE simulation demonstrates that blade orientation is a key design parameter in oscillatory flow modulation. This work is based on a peer-reviewed article published in Heat Transfer.