67% of the projects performed modelling at different scales and the linking of the models represents a considerable challenge.
The overview of FP7 NMP projects shows that linking different models (PDF version, 2.58MB) is a crucial aspect of multi-scale and multi-physics modelling.
Materials, such as solids, liquids and gases, are composed of molecules separated by empty space. Some physical and chemical processes take place at the smallest scale while certain physical phenomena can be modeled assuming the materials exist as a continuum. But most material phenomena are multi-scale in nature and methods exist that link electronic, atomistic, mesoscale and continuum simulations and transfer data from one model to another.
Different physics and chemistry may also need to be coupled at the same scale, like solid and fluid mechanics with thermodynamics or reaction kinetics. This is called here multi-physics modelling as the models are applied to the same length- and time- scales and the word multi-scaling does not really apply.