...
The finer the mesh, the more accurate the results may be. This trades off with computing power, and free plans on SimScale only have limited computing power. Additionally, often, there is a mesh fineness level after which drastically diminishing returns in precision occurs. To find out if you have attained this level, it is useful to run a mesh independence study.
Automatic Boundary Layers:
This setting allows SimScale to automatically generate cells to accurately model the boundary layers near solid surfaces. We will leave this on, as for surfaces of concern, we will use a boundary layer refinement For this specific simulation case, a global fineness of 3.0 is sufficient, as the important features of the simulation are refined with a much finer region refinement. Any level of global fineness for this specific simulation case should be permissible, as long as it is balanced out with the correct combination of a decreased global gradation rate and does not cause mesh-dependency in results, i.e. seeing sharp shifts in the velocity gradients across mesh boundaries.
Automatic Boundary Layers:
This setting allows SimScale to automatically generate cells to accurately model the boundary layers near solid surfaces. We will leave this on, as for surfaces of concern, we will use a boundary layer refinement to manually set the boundary layers.
...
Global gradation rate: 1.22
Ratio Maximum ratio of sizes between neighboring cells. Can be any value between 1 and 3, depending on the opinion on the simulationistof the simulationist.
The smaller this value is, the smoother the gradient between fine and coarse cells. If using especially coarse meshes, the global gradation rate should be decreased to prevent mesh dependency.
Refinements
Refinements are adjustments made to mesh characteristics to improve the performance of the simulation.
...