Two-way fluid-structure interaction

You can perform seamless fully-coupled thermal-flow-structural analyses with two-way fluid-structure interaction (FSI). The fluid mesh moves based on displacements computed by Simcenter Nastran. You can display the structural, thermal, and flow results together.

Fluid velocities around a displaced wing with engineering stress displayed

Data exchange between the solvers

When you perform an FSI analysis, the flow solver passes pressures and shear stresses exerted by the fluid domain on the flow surfaces to Simcenter Nastran, which passes the nodal displacements on these surfaces to the flow solver. On these flow surfaces, you must define Flow Surface simulation objects and indicate that data exchange occurs at each coupling time.

The flow solver identifies a flow surface with no fluid-structure coupling as a fixed wall. It is not free to move like the rest of the fluid domain.

Fluid mesh moving method

When you perform an FSI analysis, the fluid mesh in the FEM is not modified. Instead, the flow solver derives the nodal displacements in the fluid mesh from the nodal displacements on the flow surfaces.

Fluid velocity animation around a baffle with engineering stress displayed

This method requires that the structural displacements are small so that the fluid mesh topology is preserved throughout the simulation.

Where do I find it?

Application	Pre/Post
Prerequisite	An active Simulation file with Simcenter 3D Multiphysics as the specified solverCoupled Flow-Structural or Coupled Thermal-Flow-Structural as the specified Analysis Type

Defining exchanged data for FSI

Command Finder	Modeling Objects
Location in dialog box	Type list→Flow-Structural Coupled Solution Parameters or Thermal-Flow-Structural Coupled Solution Parameters→Additional Parameters group→Pass Flow Boundary Condition Pressures and Shear Stresses to Structural Solver and Pass Structural Displacements to Flow Solver

Defining flow surfaces for FSI data exchange

Command Finder	Flow Surface
Simulation Navigator	Right-click the Simulation Objects node→New Simulation Object→Flow Surface
Location in dialog box	Fluid-Structure Interactions group→Fluid-Structure Coupling list→Coupled

How do I

Define coupled solution parameters

Learn more

Simcenter 3D Multiphysics overview

Mapping results data to another model in Simcenter 3D Multiphysics

Defining multiphysics solution steps

Controlling time steps in a coupled solution

Requesting structural output for Simcenter 3D Multiphysics

Requesting thermal, flow, and thermal-flow output for Simcenter 3D Multiphysics

Adding time points to a structural solution to match a reference solution

Previewing Multiphysics solver syntax

Analyzing multiphysics results

Controlling the export of nodes connected to flow elements

Flow Surface

Look up more details

Simcenter 3D Multiphysics boundary conditions

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

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Related Topics

SOL 401 nonlinear capabilities

Two-way fluid-structure interaction, Simcenter 3D 2021.1 Series

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