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Scaling and similarity provide valuable tools for planning of gas mixing experiments and for extrapolating the experimental findings. With some experience the analyst is able to differ important and negligible influences. To this end he has to identify the relevant parameters, processes or mathematical models in one initial step. However, without experience this initial choice might be wrong or incomplete and lead to wrong conclusions. Under these conditions even the methods importing a certain knowledge, like the equations approach, will not improve the situation considerably.

In complex settings the requirement for scaling can be so strong, such that similarity becomes identity and therefore obsolete. In these cases spatial or temporal decomposition of the problem can relax the requirements as demonstrated for the garage example. A general conclusion for the material scaling in gas mixing experiments is, that the replacement of hydrogen by the model fluid helium violates the similarity conditions only minor. With a slight geometrical scaling (slightly larger experiment with helium) the similarity will be even improved. The application to the evaporation of a LH2 pool is recommended for an exercise.

In a future extension of this report the scaling found in the literature for reactive flows, including fires and gas explosions, will be summarised. The methodology will be applied to some standard benchmark cases where hydrogen fire or explosions have been modeled.

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Page last modified on September 15, 2008, at 11:47 PM