Scientific Assessment Procedure (UU. The scientific assessment procedure will be based on the information contained in the completed questionnaire, which is returned by the model developer or the expert user. An example of a suitable questionnaire is provided in Section 9.1 of this document. The approach taken is to clearly specify the purpose of the model, produce a consensus of what ‘science’ is required for the model to meet its application(s) and to determine whether the ‘science’ is present in an adequate form in the model. To carry out a scientific assessment of a given model, detailed information is required regarding the physical, mathematical and numerical basis of the model under consideration. At the most fundamental level, the results produced by the model must (broadly) adhere to theoretical expectations and be reproducible. For example, if two different groups investigate an identical scenario using two different methods of analysis (different models or a different application of the same model) and obtain significantly different results, then the details of both models must be available for scrutiny. This is essential in order to scientifically resolve the reason(s) for the differences. The model must be based on sound physical principles which build on or use modelling techniques that have been accepted, and are therefore well understood, through publication in high quality peer reviewed journals or appropriate industrial reports or reports to clients. It may in fact be more appropriate for an innovative model, which has not been through extensive peer review and testing, to be published in an industrial context as it may not contain the new or innovative developments or ideas suitable for publication in a peer reviewed journal. Any innovative modelling aspects included in the model should be appropriately highlighted and their use justified through appropriate scientific argument, verification and validation. A source term in a model is one which is not normally accommodated in the unsteady, convective or diffusive terms. They are meant primarily for internal generation processes such as heat generation in a fluid, production of a chemical species in a reaction, the generation of turbulent kinetic energy, etc. However when the corresponding physical quantity is destroyed rather than produced, the source term becomes negative and may be known as a sink term. As CFD models for the safety analysis of FCH technologies are associated with numerous physical phenomena, different m...
