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The present work details a study of the heat flux through the walls ofan internal combustion engine. The determination of this heat flux isan important aspect in engine optimization, as it influences thepower, efficiency and the emissions of the engine. Therefore, a set ofsimulation tools in the OpenFOAM® software has been developed,that allows the calculation of the heat transfer through engine wallsfor ICEs. Normal practice in these types of engine simulations is toapply a wall function model to calculate the heat flux, rather thanresolving the complete thermo-viscous boundary layer, and performsimulations of the closed engine cycle. When dealing with a complexengine, this methodology will reduce the overall computational cost.It however increases the need to rely on assumptions on both theinitial flow field and the behavior in the near-wall region. As theengine studied in the present work, a Cooperative Fuel Research(CFR) engine, is a simple single cylinder pancake engine, it waspossible to implement more complex and numerically demandingmethodologies, while still maintaining an acceptable computationtime. Both closed and full cycle simulations were thereforeperformed, for which the heat flux was calculated by bothimplementing various wall function models and by resolving thecomplete thermo-viscous boundary layer. The results obtained fromthe different kind of simulations were then compared to experimentalheat flux data, which was measured using a thermopile type heat fluxsensor in different locations in the CFR engine. By comparing theresults from the different types of simulations, a performanceevaluation of the used methodology could be carried out. It wasfound that the heat flux obtained by resolving the thermo-viscouslayer was accurate compared to experiments, while the wall functionswere not able to correctly capture the heat flux. Full cycle simulationsresulted in a slightly improved result, especially when resolving theboundary layer, but due to the increased computational cost, thismethod does not seem beneficial

Evaluation of Wall Heat Flux Models for Full Cycle CFD Simulation of Internal Combustion Engines under Motoring Operation