Flow + Structural
Flow + Structural solution must be selected to perform a fully-coupled Fluid Structure Interaction (FSI) simulation. This technology is also referred to as Direct Coupled Fluid Structure Interaction (DC-FSI) in Altair AcuSolve.
FSI problems occur in physics whenever the flow over a structure causes deformation which in turn may influence the behavior of the flow. In order to accurately capture this complex physics, the flow and structural solvers must be fully coupled by running both simulations in tandem and exchanging data at each time step or multiple time within each step. This technology can be used for large structural deformations along with geometric and material non-linearities.
- Setup the flow solution.
- Setup the structural solution.
- Couple the flow and structural using the Coupled solution.
In the flow solution, the flow boundary conditions, material properties, solution parameters need to be provided. In the structural solution, the loads and constraints on the model to be provided. Please note that both simulations need to be run as transient with the same time step size and total simulation time as they are run in tandem, and data is exchanged for every time step. The flow solver (Altair AcuSolve) computes the forces and moments and passes them to structural solver (Altair OptiStruct) and structural solver computes the displacement and sends it back to flow solver and this happens multiple times for each time step. This is all done in the background with zero or minimum user intervention.
Direct-Coupled Fluid-Structure Interaction (DC-FSI) Cycle:
In the “Coupled Solution” panel, the Flow and Structural Solutions can be selected from the drop-down list next to Solution 1 and Solution 2. The interface surfaces between the fluid and solid needs to be selected. The coupling type can be set to Bidirectional or Unidirectional. There are two types of Unidirectional depending on data is transferred from Flow to Structural or Structural to Flow. The fluid forces, moments can be scaled before they are sent to the structural solver. This will help obtain robust solution, especially at start up.
The coupling settings for both solvers to be provided in the Solution Parameters panel.
Right click on “Results” and select “Update” to launch both AcuSolve and OptiStruct in the background. Once the simulation is completed, the results will be automatically displayed in SimLab for postprocessing.