Initial Guess steady vs unsteady simulations

MissCFD · July 1, 2016, 18:43

Hello,

Does the initial guess has an influence on solution only in the case of unsteady simulations ?

Thank you for your answer.

ghorrocks · July 2, 2016, 07:49

Some fluid flows can bifurcate - this means different initial conditions can lead to different final steady state conditions. So the initial condition can flip from one final condition to another.

An example is a 2D planar venturi which is slightly too big an angle to keep the flow attached, so you get a separation. The flow will stick to either the top or bottom wall due to the Coanda effect. But which one it sticks to depends on the initial condition.

July 1, 2016, 18:43	Initial Guess steady vs unsteady simulations	#1
MissCFD Senior Member Join Date: Aug 2014 Posts: 160 Rep Power: 12	Hello, Does the initial guess has an influence on solution only in the case of unsteady simulations ? Thank you for your answer.

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July 2, 2016, 07:49		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,868 Rep Power: 144	Some fluid flows can bifurcate - this means different initial conditions can lead to different final steady state conditions. So the initial condition can flip from one final condition to another. An example is a 2D planar venturi which is slightly too big an angle to keep the flow attached, so you get a separation. The flow will stick to either the top or bottom wall due to the Coanda effect. But which one it sticks to depends on the initial condition.