Accuracy degree for an airflow simulation

Paris Hdez

hi! I am trying to simulate the flow in a ship's hold. At one area of this hold some measurements of wind velocity where taken. When comparing the air speed at this same points in my simulation with those measured the differences are of the order of 30%. Should I content myself with these results? Which grade of accuracy it is possible to reach with CFD's? The dimensions of the model are really big (180x20x7m) this does not allow me to make cells so small as I would like to, though I think the actual dimensions of the cell (0.5³ the biggest ones and 0.125³ the smallest ones) should be enough to get decent results. Please help me, I've allready tried it all and I am really going mad. Thank you very much, Paris