# Changes between Version 2 and Version 3 of MiscellaneousQuestions

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Oct 24, 2008, 10:04:02 AM (15 years ago)
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• ## MiscellaneousQuestions

 v2 part blank. Or perhaps you can discuss the question in more detail. == Why does ANUGA get so slow when meshes are refined == Two reasons: * With smaller triangles timesteps tend to become smaller due to the CFL condition * The computation time per timestep grows more than linearly with the number of triangles. Here is why {{{ Let h be the grid size. The number of cells (triangles) N will normally be proportional to h^{-2} The size of the timesteps will be proportional to the grid size, and so the number of timesteps is proportional to h^{-1} = N^{1/2} So the computational cost (solution time) will be proportional to (number of cells) x (no of timesteps) = N x N^{1/2} = N^{3/2} log (Time) = 3/2 log( N). So increasing the grid size from 100 cells to 1000 cells grows the computational time by 10^{3/2} (about 30). }}} ----- = [FrequentlyAskedQuestions ANUGA FAQ] =