This Technical Opinion Paper (TOP) studies the emerging use of computational fluid dynamics (CFD) as an additional tool for the evaluation of safety cases implying thermal hydraulics. CFD allows a finer description of the phenomena compared to the present system-scale tools. This appears promising but also raises new questions in the assessment of safety studies and its use is currently still limited to a relatively small number of applications. The development of CFD is a fast-evolving and relatively recent activity in the context of nuclear safety. The Computational Fluid Dynamics Task Group (CFDTG), which is part of the Nuclear Energy Agency (NEA) Committee for the Safety of Nuclear Installations (CSNI) Working Group on the Analysis and Management of Accidents (WGAMA), has been continuously conducting collaborative work in this field since an explanatory meeting in 2002.