What is the fine-grained topic of the following text: These real applications, used by academia and industry, running daily in production in existing European (PRACE Tier-0 systems) or national HPC facilities, have been selected by the different partners in order to cover a wide range of scientific and engineering domains (geophysics, fusion, materials, particle physics, life sciences, combustion, aerodynamics, weather forecast…), as well as a wide range of hardware and software requirements. Only return the topic.
Real applications used in various scientific and engineering domains in European or national HPC facilities.