Implementation and Validation of 1D-3D CFD Co-simulation for Complete Cooling System

Abstract: The internal combustion engines, the electric motors and the batteries generate signicant amount of heatduring operation that need to be extracted by cooling systems. A cooling system is designed and installedto extract the generated heat and maintain the system temperature in an optimal range. Overheating hasseveral unfavorable outcomes such as less durability and lower energy eciency. The cooling system consistsof several components such as hoses, ow splitters, valves, heat exchangers, coolant, pump etc. The coolant,as the working uid, is pumped to dierent heat generator component to enable the cooling down process.Computational Fluid Dynamics (CFD) is a powerful and cost ecient tool to simulate the cooling pro-cesses, design and evaluate the performance of a cooling system. Generally, one dimensional CFD is acommon approach to interpret and explain the cooling processes in the automotive industry due to highexibility and computational cost eciency. Also, three dimensional CFD is employed whenever it is re-quired to study complex physical phenomena and provide detailed information. Additionally, it is possibleto couple one dimensional and three dimensional CFD approaches to simulate cooling processes. Not onlyis the coupled 1D-3D CFD approach able to capture complicated physical processes but also is exible andcost ecient.The objective of this master thesis is to implement 1D-3D CFD coupled simulation on internal combustionengines' cooling system and evaluate the advantages and disadvantages of this method. The performanceof this method is examined in dierent case studies with dierent ow and geometrical characteristics. Theeect of various turbulence models and numerical settings are investigated on the quality of the coupledsimulations' results. The coupled simulations are carried out using GT-SUITE and STAR-CCM+ software.The performed simulations show that the coupling method is a convenient approach which is able tocapture detailed physics with high precision requiring reasonable computational costs. The results of thecoupled simulations depict agreement with the uncoupled 1D CFD simulations, although some discrepanciesare observed in complex case studies. Also, it is shown that the coupled simulations are sensitive to numericalsettings and physical models, consequently, the case setup should be optimized carefully