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- Liquid film dynamic on the spray impingement modelingPublication . Rodrigues, Christian; Barata, Jorge M M; Silva, AndréThe present paper addresses a liquid film submodel included into a computational model that aims at reproducing the spray impingement phenomena. This numerical extension incorporates the spread of the liquid film over the neighboring nodes due to the dynamic motion induced by the film inertia and also the exchange of mass between the liquid layer and the incident and splashing particles. Moreover, a dimensionless film thickness parameter is embedded in the submodel by mean of an experimentally deduced correlation that can be fitted and updated to specified conditions. In order to realize how the model behaves with different influencing parameters, a thorough investigation is performed: the results that are obtained with and without the inclusion of the liquid film submodel are compared against the experimental data for two crossflow velocities. The integration of the computational extension with the spread/splash transition criterion is also evaluated by considering two types of expressions: one that includes the effect of the film thickness and one that does not. The results show that the latter option combined with the submodel does not distinctly enhance the simulation results, contrary to what happens with the transition criterion that considers the film thickness as an influencing parameter. In this case, the model with the computational extension reveals better prediction results, which indicates the necessity of considering it for spray impingement simulations along with a splash threshold that depends on the liquid layer.
- Spray impingement modelling: Evaluation of the dissipative energy loss and influence of an enhanced near-wall treatmentPublication . Rodrigues, Christian; Barata, Jorge M M; Silva, AndréThe goal of the present research is to contribute to improve the knowledge about the spray impingement topic through a numerical study that is aimed at investigating the impact of using the dissipative energy terms that are available in the literature when they are embedded into a specific dispersion model. Comparing all the numerical approaches, a non-negligible disagreement is observed between the relationship proposed in the original model and the other ones drawn from the literature. This fact evidences the influence of the energy dissipated term on the secondary atomization outcome. The present work also provides a comprehensive study on the estimation of the energy dissipated during the splash event. This is a major contribution to the permanent literature since the few works found only addressed the spread regime. In addition, this paper gives an in-depth analysis on the influence that an enhanced treatment of the boundary layer in the region close to the wall may have in the simulation of such flows. The work revealed that this near-wall droplets tracking method provides an alternative way to increase the accuracy of the dispersed phase and achieve more consistent results without the necessity of a direct mesh refinement.
- Influence of the Spread/Splash Transition Criteria in the Spray Impingement ModelingPublication . Rodrigues, Christian; Barata, Jorge M M; Silva, AndréThe present paper reports a numerical study of a spray impinging on a surface through a crossflow. This work is intended to study the influence of the spread/splash transition criteria in the modeling of the spray impingement phenomenon. Several experimental correlations available in the literature are inserted in the same base model and the results are tested against experimental data. It can be concluded that the employment of an accurate transition criteria can improve the quality of the results.