Seminars

Abstract: Chemistry models can be assessed by sensitivity studies. Sensitivity studies provide a measure of how responsive target quantities of interest (QoIs) are to changes in model parameters. The adjoint equations have been derived for laminar, incompressible, variable density reacting flow and applied to hydrogen flame simulations. From the adjoint solution for each QoI, the sensitivity of the QoI to the chemistry model parameters has been calculated. The results indicate the most sensitive parameters for flame tip temperature and NOx emission. Such information can be used in the improvement of chemistry models by pointing out which are the critical parameters for relevant simulation results.

Additionally, a broader goal for chemistry model development is set through the adjoint methodology. A new quantity, termed field sensitivity, is introduced to guide chemistry model development. Field sensitivity describes how information of perturbations in the flowfield propagates to specified QoIs. The field sensitivity, mathematically shown as equivalent to finding the adjoint of the primal governing equations, is obtained for laminar hydrogen flame simulations using three different chemistry models. Results show that even when the primal solution is sufficiently close for the three models, the field sensitivity can vary. This result indicates that the different models propagate information differently.