Steady-state simulation to start a transient simulation

smagmon · May 17, 2009, 06:31

Hi all,

I am trying to observe the wave propagation inside an air-filled geometry. The idea is to observe the reflection and dissipation of the waves through time and along the geometry. In my approach the excitation was given as step displacement of one wall in my geometry. There is no output, all the other walls have the boundary conditions as stationary wall defined.
My doubt is which kind of steady-state simulation should I run to use the result in the transient one?

Can anybody help me? I will be also grate if I receive some tip!

Thanks

Jules · May 17, 2009, 14:22

smagmon,

it is very unclear to me what kind of hint you want.
I am guessing that you have a volume filled with air and that it is completely enclosed by solid walls, no inlet or outlet or opening. One wall is moving / making a step displacement, causing the waves that you want to analyze.
In that case, there would not be any fluid motion without the step displacement. You therefore would not need a starting solution, you can simply initialize the domain with zero-velocity in all directions.

Regards,

Jules

smagmon · May 18, 2009, 03:59

Hi Jules,
Sorry for my poor explanation. But you got the configuration. As you advised, I simply initialize the domain with zero-velocity in all directions. I simply initialize the domain with zero-velocity in all directions. But the step displacement was given after 5 steps, and between the initialization of the domain and the wall starting to move, a non-uniform behavior appears. There are many regions of different pressure levels that propagates as waves through the domain.

Thank you for your answer,

Smagmon

May 17, 2009, 06:31	Steady-state simulation to start a transient simulation	#1
smagmon New Member Join Date: Mar 2009 Posts: 13 Rep Power: 17	Hi all, I am trying to observe the wave propagation inside an air-filled geometry. The idea is to observe the reflection and dissipation of the waves through time and along the geometry. In my approach the excitation was given as step displacement of one wall in my geometry. There is no output, all the other walls have the boundary conditions as stationary wall defined. My doubt is which kind of steady-state simulation should I run to use the result in the transient one? Can anybody help me? I will be also grate if I receive some tip! Thanks

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May 17, 2009, 14:22		#2
Jules Member Jules Bell Join Date: May 2009 Posts: 32 Rep Power: 16	smagmon, it is very unclear to me what kind of hint you want. I am guessing that you have a volume filled with air and that it is completely enclosed by solid walls, no inlet or outlet or opening. One wall is moving / making a step displacement, causing the waves that you want to analyze. In that case, there would not be any fluid motion without the step displacement. You therefore would not need a starting solution, you can simply initialize the domain with zero-velocity in all directions. Regards, Jules

May 18, 2009, 03:59		#3
smagmon New Member Join Date: Mar 2009 Posts: 13 Rep Power: 17	Hi Jules, Sorry for my poor explanation. But you got the configuration. As you advised, I simply initialize the domain with zero-velocity in all directions. I simply initialize the domain with zero-velocity in all directions. But the step displacement was given after 5 steps, and between the initialization of the domain and the wall starting to move, a non-uniform behavior appears. There are many regions of different pressure levels that propagates as waves through the domain. Thank you for your answer, Smagmon