Grid Adaptive LES/DNS

Combustion is currently the most widely used method of energy conversion that powers modern industry and society. This energy is provided from the combustion of fossil fuels that are a global finite resource which is diminishing on a daily basis. Emissions from the combustion of fossil fuels can also lead to environmental problems such as global warming. In order to convert energy more efficiently and less harmfully to the environment, it is desirable to gain a thorough understanding of the combustion process. The development of real combustion applications generally requires a series of experiments to test a design or theory. With the rapid growth in computing resources and numerical techniques, computer simulation testing can also be used in the design process at a fraction of the cost compared with an equivalent experiment. In addition, computer simulations can provide a wider range of information on a proposed design in a shorter time frame by sweeping through different configurations simultaneously. Current methods such as Reynolds Averaged Navier Stokes (RANS), where the time fluctuating flow equations are solved in an average form, and Large Eddy Simulations (LES), where only the smaller scales of motion are modelled are being used to simulate industrial problems. However, both of these methods require models to provide additional information that is lost due to there limitations. The proposed work will take these computational simulations to the next level by developing a hybrid method that combines LES and Direct Numerical Simulation (DNS), where all scales of motion are computed explicitly without recourse to any modelling. To the investigators knowledge, this will be the first attempt to combine LES and DNS to simulate combustion, and then compare to a much more costly full DNS. The results from this work are expected to give a better understanding of large scale turbulent combustion problems without a loss in accuracy. Finally, this method could form the basis for a robust and accurate simulation method that combustion designers can use to explore new configurations with confidence to provide the next generation of energy cheaper, safer and more environmentally friendly.