Heat sink fins design based on the Constructal Law: a CFD approach for air-cooled electronic devices

Thermal management represents a critical challenge for the reliability and lifespan of modern power electronics, such as medium-power photovoltaic (PV) inverters. This work presents a self-organizing generative design methodology for air-cooled heat sinks embedded within a realistic PV inverter enclosure, driven deterministically by the Constructal Law. Numerical simulations of conjugate heat transfer and turbulent flow are conducted utilizing the chtMultiRegionFoam solver within the OpenFOAM framework, closed with the standard κ − ϵ turbulence model. Instead of tuning predefined geometries, a specialized construction algorithm progressively expands the heat exchanger surfaces based on a local thermodynamic opportunity function. The evolution of the fluid-solid interfaces is systematically investigated across a family of solution paths under four distinct fin thickness constraints. Results demonstrate a stark continuous drop in global thermal resistance for all configurations. This trend establishes a performance trade-off where the massive gain in wetted perimeter completely outweighs the local convective degradation caused by the decay of the channel's hydraulic diameter. Among the analyzed paths, the configurations with thinner fin thicknesses (1.5 mm and 2.5 mm) yield the superior physical designs, achieving a significant reduction in the peak operation temperature compared to the conventional commercial baseline and also a substantial reduction in total material volume. This work demonstrates that allowing the geometry to grow freely in pursuit of greater currents provides a natural path to minimize systemic thermal resistance, directly embodying the Constructal Law by adapting the flow architecture to maximize performance while ensuring a rational and reduced use of material.