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Queries regarding the settings of transient two-way FSI simulation

    • be21b028
      Subscriber

      I am currently working on a two-way fluid-structure interaction (FSI) simulation in ANSYS, specifically focusing on analyzing the forces exerted by shockwaves on a tube and a pod in a hyperloop. I have encountered a few queries during the simulation setup, and I would appreciate guidance on the following matters:

      Wall Slip Conditions:
      In our simulation, we are keeping the pod and tube static while allowing the surrounding air to move. For the simulation, we need the pod wall to exhibit a no-slip condition and the tube wall to have a free-slip condition. However, it seems that achieving a free-slip condition on a specific wall is challenging without assigning the flow as inviscid. Specifying shear stress conditions and equating components to zero didn't ensure free slip. Is there a setting or approach that allows us to assume no slip on the pod wall and free slip on the tube wall without assigning the flow as inviscid?

      Transient Structural and Vortex-Induced Vibrations:
      We are coupling Fluent with Transient Structural to study vortex-induced vibrations of the pod. As the pod needs to be free to vibrate, assigning static support is not suitable. Elastic support, however, can only be applied on a planar surface, which doesn't align with our pod's geometry. Could you suggest an alternative method to allow the pod body to vibrate under the influence of fluid forces?

      Thermal Loads and Structural Response:
      Given the dynamic hyperloop environment, we must also account for temperature changes in the fluids leading to rapid expansions and contractions. Could you kindly explain the process of transferring thermal loads to the structures and capturing the resulting displacement? This is crucial for our study of the effects of temperature changes on structural integrity.

    • Rahul
      Ansys Employee

      A slip wall can be modeled by specifying zero shear under 'Specified Shear' condition.
      The Wall Dialog Box for Specified Shear
      7.4. Boundary Conditions (ansys.com)


      Thermal and structural loads:
      You can perform coupled-field analyses using a System Coupling component system in Workbench. Specifically, you can set up a one-way or two-way fluid-structure interaction (FSI) analysis or thermal-structural analysis by connecting a System Coupling component system to Mechanical, Fluent, and External Data systems.
      1.1. Types of Coupled-Field Analysis (ansys.com)

    • be21b028
      Subscriber

      What about the second query? What support should we assign to observe vortex induced vibrations?

    • Ashish Khemka
      Forum Moderator

      Hi Prateek,

      For the second query - you want the pod to be free and maybe using springs with very low stiffness might be useful.

      Regards,

      Ashish Khemka

    • be21b028
      Subscriber

      Could you please elaborate on the method of using springs on a desired surface in transient structural and measuring their deflection?

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