about the steady solution

zwdi

Hi guys, Does somebody know some criteria about the existance for steady solution and unsteady solution? In my case, I used the steady solver and got the residual to 1e-10, but the residual still has the potential to go down(the residual has no chances to stop decreasing even though I continue the iterations), does that means in my case, I couldn't get the steady solution, or in this case unsteady solver is more reasonable than from steady slover? Does someone tell me what the reason? I coarsed the mesh size, but it does not work. Thanks.