Deliverable D4.1 presents a breakthrough in the HEATWISE project, the development and validation of open-source Computational Fluid Dynamics (CFD) models for simulating and optimizing how heat moves through data centres.

Why is this important? Data centres are energy-intensive, and their cooling systems can account for up to 40% of that energy use. Efficient thermal management is crucial, both to prevent overheating and to unlock waste heat recovery as a renewable energy source.

The core tool: dataCenterDST Developed using OpenFOAM, this flexible modelling framework:

• Simulates airflow and heat patterns through server racks.
• Allows detailed analysis using both full 3D geometry and simplified porous models.
• Can incorporate real-world layouts and fan configurations.

The model was validated at the Empa pilot site in Switzerland, with tests showing its accuracy in predicting airflow, pressure drop, and outlet temperatures, with less than 8% error compared to measurements.

Advanced features: Two-Phase Cooling and Boiling Simulation The deliverable also includes a two-phase CFD model, capable of simulating boiling, a key process in next-generation liquid cooling systems. Using a custom-developed box model, the simulation captured bubble formation, heat flux, and vapor flow in direct-on-chip systems like ZutaCore.

Innovation highlight: Micro-Baffle Design To improve boiling efficiency, the team designed and optimized a micro-baffle structure that boosted heat transfer by over 57% and increased the critical heat flux by 66%, meaning better, safer, and more efficient cooling.

Bottom line: This open-source toolset is a major step forward in sustainable IT operations. It enables smart retrofitting, predictive heat modelling, and efficient cooling strategies that can maximize waste heat reuse, especially in high-performance computing environments.