## 2 Study Goals and Experiment Setup  
The present design study focuses on the development of a suitable duct geometry for the active air cooler of a high-power inverter used in an experimental electric vehicle. One of the primary challenges in this design is achieving the highest possible cooling performance within a minimal volume, ensuring effective heat dissipation while maintaining a compact structure. The increasing power density of modern inverters necessitates innovative thermal management solutions, particularly in applications where space is highly constrained.  
To address this challenge, this study explores the potential of selective laser melting (SLM) technology for manufacturing a compact and highly efficient heatsink without the geometric limitations imposed by conventional fabrication methods. By leveraging the design freedom of additive manufacturing, the proposed approach allows for the creation of optimized cooling structures that maximize heat transfer efficiency while maintaining structural integrity. Additionally, SLM enables the fabrication of complex geometries without the need for extensive support structures, reducing material waste and post-processing efforts.  
The primary goal of this research is to design an optimal hole geometry with varying cross-sectional sizes to minimize shape deformation during 3D printing while eliminating the need for additional supports. A key aspect of this approach is the use of variable hole diameters to achieve an optimal heat transfer distribution across the cooling structure. By tailoring the size of the apertures, it is possible to manipulate local airflow velocity and enhance convective heat transfer between the heatsink and the cooling medium. This strategy ensures a more uniform temperature distribution and improves thermal performance. The design workflow is illustrated in Figure 3, which outlines the step-by-step methodology used to develop and evaluate different hole geometries.  
A critical aspect of the design process is ensuring that the printed structure supports itself during the manufacturing process without the need for external supports. Theoret  
Figure 3: Flowchart of the experiment setup.  
ical knowledge of material behavior during SLM processing is essential for preventing deformation and internal stress buildup. Key factors such as critical overhang angles, laser scanning strategies, and thermal expansion effects must be considered to optimize the printing process. The disadvantages of using supports include additional material consumption, increased energy demand, and post-processing work required for their removal after 3D printing [36]. By implementing geometry modifications that inherently support the structure during fabrication, this study aims to eliminate the reliance on post-processing operations, thereby improving efficiency and reducing production costs.  
The findings from this study will contribute to the development of advanced heatsink designs tailored for additive manufacturing applications, particularly in power electronics cooling systems where compact, lightweight, and high-performance solutions are required. The results of this research will serve as a reference for future investigations into topology-optimized cooling structures that leverage the full potential of AM technology.