This proposal concerns high performance computing of fluid mechanics and heat transfer related to energy conversion. This means addressing several fundamental modelling issues such as multi-phase flow, combustion, thermal radiation and fluid-structure interaction. One or more of these issues come into the energy conversion related applications addressed in this proposal: Heat exchangers, aero engines and wind turbines. Some issues are also important for other industrial sectors such as food industry. High fidelity fluid dynamics simulations require that turbulence is modelled and treated in a proper way, meaning that either large eddy simulation or direct numerical simulation would be required. In turn this means that proper resolution of the flow scales is of the essence, which lead to large computational meshes and long computational times.