Fast computation of multi-scale combustion systems

In the present work, we illustrate the process of constructing a simplified model for complex multi-scale combustion systems. To this end, reduced models of homogeneous ideal gas mixtures of methane and air are first obtained by the novel Relaxation Redistribution Method (RRM) and thereafter used for the extraction of all the missing variables in a reactive flow simulation with a global reaction mode

The notion of energy through multiple scales: From a molecular level to fluid flows and beyond

In the present paper, we review the consistent definition of macroscopic total energy in classical fluid mechanics, as a function of the microscopic canonical Hamiltonian field, based on a Lennard-Jones model with some spatially varying external field. The macroscopic total energy (sum of mechanical and internal energy) is proved to be equal to the equilibrium ensemble-averaged Hamiltonian. In particular, the conditions for including the effects of the external field both in the macroscopic potential energy and in the internal energy are discussed. {We present the notion of energy as defined in different scientific communities, starting from the standard macroscopic systems all the way down to small ones, which are gaining an increasing popularity

Multi-scale modeling to boost fuel cell performance: From pore-scale simulations to better efficiency and durability

According to the European Commission, Europe has set itself a goal to reduce CO2 emission levels by 2050 to 80% of what they were in 1990. Fuel cells and hydrogen have potential to contribute to overcoming the energy challenges that accompany this change. In particular, fuel cells based on proton-exchange membranes (PEM) and fuelled by hydrogen and air have many attractive features, including high power density, rapid start-up and high efficiency. However, among the major technology issues that must be addressed for their commercialization and widespread use, the degradation phenomena of the membrane electrode assembly (MEA) plays a key role. In this talk, we present multi-scale morphological models and simulation tools for detailed understanding of degradation phenomena. This kind of modeling techniques can take strong advantage by recent progresses in dual-beam focused ion beam scanning electron microscopy (FIB-SEM). As an example, we investigate the effects of the catalyst distribution in the electrodes on the local fluid flow and on the loss of phosphoric acid from the membrane

Multi-scale modeling to boost fuel cell performance: From pore-scale simulations to better efficiency and durability

According to the European Commission, Europe has set itself a goal to reduce CO2 emission levels by 2050 to 80% of what they were in 1990. Fuel cells and hydrogen have potential to contribute to overcoming the energy challenges that accompany this change. In particular, fuel cells based on proton-exchange membranes (PEM) and fuelled by hydrogen and air have many attractive features, including high power density, rapid start-up and high efficiency. However, among the major technology issues that must be addressed for their commercialization and widespread use, the degradation phenomena of the membrane electrode assembly (MEA) plays a key role. In this talk, we present multi-scale morphological models and simulation tools for detailed understanding of degradation phenomena. This kind of modeling techniques can take strong advantage by recent progresses in dual-beam focused ion beam scanning electron microscopy (FIB-SEM). As an example, we investigate the effects of the catalyst distribution in the electrodes on the local fluid flow and on the loss of phosphoric acid from the membran