Then, when the mesh refines are much smaller, fewer iterations are needed to finish the solution. By using adaptive meshing, it’s possible to run the first few travels quickly while the flow develops.
Not much mesh is needed if the flow hasn’t “developed” yet. The advantage of adaptive meshing is efficiency. Situation #2: To calculate all iterations with a fine mesh can be a significant waste of time.
You still should run a few meshes, but the software will do a lot of mesh heavy lifting for you with adaptive meshing. Allowing the software to choose the areas in need of refinement based on gradient values is an advantage because it skips the need to run many, many analyses iterating meshes along the way. Predicting the size of the mesh necessary over small local regions of interest only becomes possible once the solution starts progressing. In some cases, intuition can predict where those areas may be but, in complex cases, it’s impossible to know in advance. In areas of high pressure, temperature, or velocity gradients, it’s necessary to refine the mesh for higher accuracy. Situation #1 : The form of the solution is unknown prior to solving.