Mesh quality Sample Clauses

Mesh quality. The mesh quality plays a significant role in the accuracy and stability of the numerical solution, hence the importance of checking the quality of the mesh before running the solver. To achieve a fair sensitivity analysis it is necessary to make the comparison between meshes within reasonable quality intervals. The quality indicators checked during this analysis are the following: • Orthogonal quality: the worst cells will have an orthogonal quality closer to 0, with the best cells closer to 1. The minimum orthogonal quality for all types of cells should be more than 0.01, with an average value that is significantly higher. • Aspect ratio: is a measure of the stretching of the cell. Generally, it is best to avoid sudden and large changes in cell aspect ratios in areas where the flow field exhibit large changes or strong gradients. The values provided by Fluent 15.0 are therefore the minim value for the orthogonal quality and the maximum for the aspect ratio. More information regarding the equations used to compute the value of the indicators can be found in the Fluent User’s Guide [14].Table 3 summarizes the important features for the different meshes that have been created and tested: the number of elements, the minim orthogonal quality and the maximum aspect ratios. The differences between the quality indicators for the different meshes are insignificant, being thus the solution only dependent on the level of refinement. M1 850741 0.3045 13.79 M2 1130452 0.3045 13.79 M3 1305806 0.3399 16.47 M4 1697303 0.3399 16.47 M5 2271395 0.2695 17.02 Meshes M1 and M2 have the same level of refinement for the blocks that compose the centerline of the domain (blocks number 1 to 4), differenced only by the element size of the surrounding blocks (blocks 5 and 6), and here lies the reason why they have the same quality indicators. This same characteristic is found in meshes M3 and M4, whose centerline is more refined compared to the previous meshes. Finally, mesh M5 is the one that presents the higher refinement on the centerline blocks and the surroundings. The models, boundary conditions and the approach employed in this analysis are presented in further sections of this Chapter 3, since they have been also used for the rest of the studied cases. In order to compare the results, the temperature profile for the z axis has been used, since it represents the centerline of the fluid domain and the zone where the flame lies.