Using steady state for Transient Initialization

soumitra2102 · September 13, 2019, 22:44

How will the convergence of steady state simulation of a problem will affect its transient simulation if used for initialization?

sbaffini · September 14, 2019, 04:59

Too vague.

In general, if you plan to use the same turbulence modeling approach in both steady and unsteady (laminar/DNS or RANS/URANS) then, if the steady solution makes any sense, you don't need the unsteady one.

If using RANS to initialize LES/DNS, you probably want almost converged mass fluxes and a good enough distribution of the turbulent quantities used to initialize the fluctuations

FMDenaro · September 14, 2019, 05:02

Paolo addressed the main issues.

Just to add that if you have a steady flow problem and you run a transient formulation starting from the initial steady numerical solution, you should find the code stops immediately as it reached the correct solution.

September 13, 2019, 22:44	Using steady state for Transient Initialization	#1
soumitra2102 Member Soumitra Vadnerkar Join Date: Aug 2018 Posts: 70 Rep Power: 8	How will the convergence of steady state simulation of a problem will affect its transient simulation if used for initialization?

September 14, 2019, 04:59		#2
sbaffini Senior Member Paolo Lampitella Join Date: Mar 2009 Location: Italy Posts: 2,195 Blog Entries: 29 Rep Power: 39	Too vague. In general, if you plan to use the same turbulence modeling approach in both steady and unsteady (laminar/DNS or RANS/URANS) then, if the steady solution makes any sense, you don't need the unsteady one. If using RANS to initialize LES/DNS, you probably want almost converged mass fluxes and a good enough distribution of the turbulent quantities used to initialize the fluctuations FMDenaro and soumitra2102 like this. Last edited by sbaffini; September 14, 2019 at 07:09.

September 14, 2019, 05:02		#3
FMDenaro Senior Member Filippo Maria Denaro Join Date: Jul 2010 Posts: 6,896 Rep Power: 73	Paolo addressed the main issues. Just to add that if you have a steady flow problem and you run a transient formulation starting from the initial steady numerical solution, you should find the code stops immediately as it reached the correct solution. soumitra2102 likes this.

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