The Fluid–Solid Interaction Interface
Using the Fluid–Solid Interaction () interface, you can model phenomena where a fluid and a deformable solid affect each other. The interface includes a predefined condition for the interaction at the fluid–solid boundaries. Arbitrary Lagrangian–Eulerian Formulation (ALE) is used for incorporating the geometrical changes of the fluid domain.
Using a stationary or a time-dependent study, the Fluid–Solid Interaction interface models bidirectional coupling between solids and fluids.
You add a predefined Fluid–Solid Interaction interface from the Fluid–Structure Interaction () group in either the Structural Mechanics branch () or the Fluid Flow branch () of the Model Wizard or Add Physics windows. Laminar Flow and Solid Mechanics interfaces are then added to the Model Builder.
In addition, the Multiphysics node is added, containing the multiphysics coupling Fluid–Structure Interaction.
At the same time, a Moving Mesh node with a Deforming Domain subnode is created under Definitions. For more information, see Deforming Fluid Domains.
On the Constituent Physics Interfaces
•
The Laminar Flow interface is described in The Single-Phase Flow, Laminar Flow Interface. When the CFD Module is available, turbulent flow is supported through the inclusion of a number of turbulence models.
•
The Solid Mechanics interface is described in The Solid Mechanics Interface.
•
The Deforming Domain feature is described in Moving Mesh Features.
In 2D, plane stress or plane strain assumptions can be selected in the Solid Mechanics interface. Only the plane strain (default) should be used together with the FSI coupling.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined couplings, all specific settings are included with the physics interfaces and the coupling features.
However, if physics interfaces are added one at a time, followed by the coupling features, these modified settings are not automatically included.
For example, if a Moving Mesh, a Laminar Flow, and a Solid Mechanics interfaces are added, COMSOL Multiphysics adds an empty Multiphysics node. You can choose from the available coupling features, but the modified settings are not included.
Table 15-6: Modified Settings for The Fluid–Solid Interaction Interface.
Physics Interface or Coupling Feature
Modified Settings
Moving Mesh
A Deforming Domain is added, where the Selection is set to Manual in the Domain Selection section.
Solid Mechanics
For the Solid Mechanics interface, under Discretization, the Displacement field is set to Quadratic Lagrange.
Laminar Flow
No changes.
Fluid–Structure Interaction
The Selection is set to All boundaries in the Boundary Selection section.
The corresponding Solid Mechanics and Laminar Flow interfaces are preselected in the Coupled Interfaces section.
The Fixed geometry coupling type is set to Fully coupled in the Fixed Geometry section.