# Impact of Mesh Resolution and Temperature Effects in Jet Ejector CFD Calculations
## 4 Conclusions  
This paper studies the differences observed when using a coarse mesh and a refined mesh in CFD studies of jet ejectors. Traditionally, the studies found in the literature use rather coarse meshes, with a very limited number of cells. Today, the computational capacity available for these calculations has greatly increased and allows for the use of more precise meshes. In this paper, the use of one of these coarse meshes is compared with a refined mesh. This refined mesh is also adaptive and changes locally depending on the pressure gradients introduced by the shock waves, thus improving the accuracy of the calculation in those areas that require it. The results obtained from this comparison show significant differences in predicting the jet ejector behavior. These differences do not affect the jet ejector behavior under critical conditions, but they do affect the critical point, where the transition between critical and subcritical behavior occurs, and the behavior under subcritical conditions. This study shows that with the coarser mesh, the entrainment ratios obtained in the subcritical zone present a more constant behavior in the downward slope of the ejector work map. On the other hand, for the more precise refined mesh, the results show a more detailed and intricate behavior with slight variations in the subcritical slope. The presented approach is one of the possibilities of the meshing strategy. Two different refinements have been applied: block refinement in specific regions and adaptive refinement based on the pressure gradient field function. They were applied sequentially;  
Figure 12: Graphical representation of corrected default temperature and Tv primary inlet temperature case. however, it is possible that using intermediate block refinement in conjunction with pressure gradient refinement could achieve similar results with a lower cell count. Additionally, the further optimization of the block regions and gradient threshold values could enhance the efficiency of the meshing strategy. In order to evaluate the repeatability of the results with the refined mesh, a study has been carried out by proportionally varying the temperatures at the primary and secondary inlets. In this study, the reference case has been compared with a case where both temperatures have been increased by 10% and another case where they have been increased by 20%. By increasing the two temperatures in the same proportion, the energy of the two flows increases proportionally and, as expected, the results obtained in the three cases are similar, showing the repeatability of the results obtained for the reference case. The distributions of the Mach number inside the ejector have also been compared, observing the differences introduced by the ejector's behavior under critical, subcritical, and backflow conditions. Finally, the differences in ejector behavior have been studied when only the temperature of the primary is changed, increasing its value by 20% and leaving the temperature of the secondary constant. In this case, differences are observed since the primary flow increases its energy without changing the energy supplied to the secondary inlet. These differences translate into changes in the jet ejector behavior in the critical zone. However, these differences are smaller in the subcritical zone. Correcting the ejector map when working with different temperatures can be relevant and must be considered when working with these maps. The publication of these maps while clearly defining all the boundary conditions used to obtain them is essential to be able to perform their proper correction when they are used. Overall, this study has achieved its intended objectives. The key contribution lies in the sensitivity of the simulations, particularly in the meshing strategy, which has successfully captured effects that remain undetected at the mesh resolutions commonly used in the literature.