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[Jirong]

Hi All,

I'm simulating the water flows though a compliant tube, by using fluent and transient structural. I used constant velocity inlet (0.1m/s) as the boundary condition. And outlet used pressure boundary condition and set it to be zero. But I found the result looks very wired at beginning. The pressure drops rapidly and then stabilized. I chose two points to plot pressure vs. time to show the pressure drop, the first one is the point on the inlet another is the center point at the middle of the domain. The straight tube even had deformation because of this. I cannot understand it from the fluid mechanics I learned, I guess it is due to complaint tube, if anyone could give me a hint about how this happened, I would really appreciated it .

Thanks,

Jirong

[YasserSelima]

How did you initialise the flow?n

[Keyur Kanade]

What are operating conditions? Which models you are using? nPlease check some Fluent tutorials. You may find many posts on forum regarding tutorials. nRegards,nKeyurnHow to access Ansys Online Help DocumentnHow to show full resolution imagenGuidelines on the Student CommunitynHow to use Google to search within Ansys Student Communityn

[Jirong]

Hi YasserSelima , nI'm using standard initialization from inlet for this case.Hi Keyur,nThe operating pressure set to be 13332 Pa and I'm using Laminar flow. n

[YasserSelima]

I think the reason for this sharp pressure change at the beginning is that you have transient solution at the beginning .. i.e, the velocities and pressure did not reach its steady-state value (close to steady state) ... If you want to avoid, run the case is steady without coupling , then start unsteady FSI simulation. And anyway, I don't think this is affecting the result of your simulation except for the first few timesteps ... n