4 Replies Latest reply on Aug 16, 2018 12:25 PM by Christopher Schaefer

    How does FSI ( fluid structure interaction) work?

    Yull Hsbrg

      I am currently trying to run a wind analyse and to import the data into simulation environment. What goals shall I predefine? In general, how critical is it to define correct goal in CFD and does it impact  the simulation results enormously?



        • Re: How does FSI ( fluid structure interaction) work?
          Christopher Schaefer

          Can you give us more detail as to the nature of the flow and the structure involved?

          Is your flow study steady-state? Are you transferring pressure/forces or temperatures (or both?)

          If purely structural, how are you expecting the structure to behave? (small or large displacements)

            • Re: How does FSI ( fluid structure interaction) work?
              Marius Moselle


              I am working with Solidworks 2017 and I am tryng to do the same thing with the blood with fixed flow and pressure.

              I need to simulate the blood interaction with a flexible structure.

              Where to begin please ?

              Best Regards,


              Moselle Marius

                • Re: How does FSI ( fluid structure interaction) work?
                  Siavash Khajehhasani

                  In a nutshell, you need to perform a flow simulation for blood using non-newtonian fluid properties which represents the blood. Then, export flow sim results to structural analysis (tools>flow sim>tools>results>export results to simulation (if I remember correctly)). Flow results with be extracted in terms of pressure and shear stresses to the structure and with be your input loads in sim. For the flexible structure, you may need nonlinear module for stress analysis. Hope it helps.

                  • Re: How does FSI ( fluid structure interaction) work?
                    Christopher Schaefer

                    There's not a straight-forward approach to this. Since the structure is flexible, it's response is highly non-linear to the transient pressure waves the fluid will induce.  Therefore your structure's stiffness will vary greatly with the applied pressure.  Re-define the scope of your project and simplify the problem, if possible.

                    Are you interested in a final deformed shape?  Is there a comparable solution to another existing piece of geometry you can compare to? Or are internal structural stresses the final product you wish to gain? Is the flow assumed to pass through or by the structure such that pressures behind it will influence the stiffness response?  Or is this more like a fixed flow (laminar or turbulent?) against a "plate?"  If you assume flow conditions, simply, as generating a defined pressure shape then you need only craft the final pressure profile as a boundary condition on to the structure itself and forgo CFD.

                    Or, you may need to use a simplified CFD analysis to generate the fluid pressure on to a "dummy" structure in order to gain insight as to the pressure distribution.

                    If, however, (returning to the first paragraph) the structure's shape will change significantly then the fluid regime will change and, hence, the fluid pressure will change.  This is considered two-way fluid-structure interaction and is presently not supported by these tools.