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 December 5, 2005, 06:43 Hello CFD-Friends. Does anyon #1 New Member   Hilgert Marco Join Date: Mar 2009 Posts: 5 Rep Power: 9 Hello CFD-Friends. Does anyone know if there´s a possibility to start a transient simulation from a converged steady-state solution. Up to now, I managed it by copying the U,p,k,epsilon files to the time-directory of a turb foam case with the same mesh. Although I have very low final residuals in both, the transient and the steady-state case, the values of the pressure loss ,this is what I´m looking for, differ a lot.

 December 5, 2005, 07:03 Yes, easy: just set your start #2 Senior Member   Hrvoje Jasak Join Date: Mar 2009 Location: London, England Posts: 1,783 Rep Power: 22 Yes, easy: just set your startTime and startFrom parameters in system/controlDict to start from the steady-state result. Enjoy, Hrv __________________ Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk

 December 5, 2005, 10:50 Thank you for your quick respo #3 New Member   Hilgert Marco Join Date: Mar 2009 Posts: 5 Rep Power: 9 Thank you for your quick response but I´m having a little trouble understanding your message. Problem 1: I use simpleFoam for the steady state solution and turbFoam for the transient simulation, so I have to create a new case, either by cloning the steadystate case, or by building a new case with turbFoam and copying the field data piece by piece. Problem 2: Analysing the solution brought out big differences between the 2 simulations. Have you ever experienced huge differences (pressure loss nearly twice as high) between steady-state and transient simulation although the final residuals are of order 1e-7. The flow is obviously unsteady. A short problem description: flow through a baffle, simple geometry like an elbow divided in several channels, Newtonian, incompressible,2D,inlet-velocity = 24.9 m/s, pressure outlet, fine and good mesh,structured in near wall regions, discretisation scheme: only first-order accurate, nu = 2,8e-5.

 May 26, 2006, 18:03 Hello, Suppose I wanted to #4 New Member   Jeff Allen Join Date: Mar 2009 Posts: 11 Rep Power: 9 Hello, Suppose I wanted to compose an unsteady case, in which the acceleration due to gravity was changing with respect to time (ie: changing each time step). Would it be possible to simply create say a /0/"g" file, in which a separate data file is called? What would be a good way to accomplish this? Resp. Jeff

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