Advances in the characterisation of reactive gas and solid mixtures under low pressure conditions

• Splitting methods are used to analyze reactive gas–solid mixtures.
• Closure laws used include interfacial friction, heat transfer and reactions kinetic.
• A new integration procedure is proposed for handle stiff source term conditions.
• It shows good results for shock and rarefaction waves, and dust combustion problems.
• It is used to simulate a 3D dust mobilisation accident sequence within ITER.

This work describes the use of splitting methods in the analysis of reactive two-phase mixtures of gases and particles under conditions that make the source terms very stiff. In our particular case, these are low pressure, small particles, high solid concentration, and very dense solids. The gas phase is considered a perfect gas and the solid one is assumed to be incompressible. The integration of the source terms proposed seems to help tackle without difficulty the type of dust mobilisation and combustion problems studied: This consists of an implicitisation of the source term performed after the evaluation of the advection problem. Some numerical results are included; they correspond to a mobilisation of the mixture by means of shock, a mobilisation problem provoked by a rarefaction wave, and the combustion of tungsten-dust in a reacting atmosphere. An example of a 3D dust mobilisation sequence inside the vacuum vessel (VV) of the ITER (International Thermonuclear Experimental Reactor) completes this work.