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Fluid-Structure Interface Modeling Parameters dialog box (Acoustics Transient BEM)

Modeling Object
Name Sets the name of the modeling object.
Label Sets a unique numerical identifier for the modeling object.
Properties
Description Lets you specify a description for this modeling object. Enter a brief description or click to open a text editor, where you can enter a longer description.
Type of Coupling Specifies the type of coupling for the Transient Acoustic BEM solver.**Effect of Structure on Fluid Only (WEAK)**Transfers the effect of structural vibration to the fluid only, and ignores the effect of the fluid pressure on the structure.
Search Units Specifies the search unit to define which elements are to be coupled.AbsoluteUses a normal line in each integration point of the structural element; the closest acoustic element within a certain distance is searched for the outward and inward specified distances.RelativeUses relative model units based on the entire structural model, and uses a scaled distances (for example, 0.2 or 0.3 times) of the entire structural model to search for acoustic elements.The acoustic element center is considered to determine which fluid element is affected by the one-way coupling. To avoid software instabilities, use a search distance greater than one-half of the element size for both Relative and Absolute selections.
Outward Normal Search Distance****Inward Normal Search Distance Specifies the distance to search in the outward normal direction to detect the fluid-structure interface.Specifies the distance to search in the inward normal direction to detect the fluid-structure interface.Note: If no acoustic element is found within the search distance, the elements are not coupled. If a second acoustic element on the same side is found within that distance, only the closest one is coupled. If the structural mesh is to be coupled on both sides, the procedure is repeated for the other side of the structural mesh. The search distance should be large enough to couple all structural elements with the acoustic mesh, but small enough to avoid coupling structural elements that are not directly exposed to the fluid (for example, in the case of a double-walled structure where the outside wall is not acoustically coupled to a cavity inside).
Fluid Interface
Fluid Element Side Specifies the fluid elements to define the fluid part of the fluid-structural interface. You can specify the side of the acoustic mesh to which the vibration is transferred. Only Top and Bottom are available for Transient Acoustic IBEM.Top and Bottom — Transfers the vibration to the top and bottom side of the acoustic mesh.
Fluid Elements for the Interface Specifies the fluid elements to include in the interface.All — Includes all the fluid elements for the fluid interface.Specify Included Elements — Includes a group of fluid elements for the fluid interface that you select from the fluid mesh or that you select by group reference.
Structural Interface
Structural Elements/Faces for the Interface Specifies the structural elements or the structural entities to include in the interface.All Structural 2D Elements — Includes all the structural 2D shell elements for the structural interface.Specify Included 2D Elements or 3D Element Faces — Includes a group of structural 2D shell elements or a group of structural 3D element faces for the interface that you select from the structural mesh or that you select by group reference.
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Fluid-Structure Interface Modeling Parameters dialog box (Acoustics Transient BEM), Simcenter 3D 2021.1 Series

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Source: https://docs.sw.siemens.com/en-US/doc/289054037/PL20200601120302950.advanced/xid1930914 · retrieved 2026-07-17