OpenFOAM Integration with Fortran Solid Solver using Immersed Boundary Method
Published:
Project Overview
This project focuses on the development of a custom solver for OpenFOAM that enables fluid-structure interaction (FSI) simulations by coupling it with an external, Fortran-based 3D solid mechanics solver. The integration is achieved through the Immersed Boundary Method (IBM), allowing for the simulation of deformable solids within a fluid flow. The project is a work in progress, with a functional implementation that can be further improved.
Key Features
- Fluid-Solid Coupling: Implements a continuous forcing Immersed Boundary Method to couple a Fortran solid solver with the OpenFOAM fluid solver.
- Custom OpenFOAM Solver: The standard
icoFoamsolver is modified to include the IBM source term, enabling the interaction between the fluid and the immersed solid. - Interoperability: Demonstrates the ability to link Fortran subroutines with C++ code in OpenFOAM, creating a shared library for the solid solver.
- 3D Simulation: The solver is designed for 3D simulations, handling the complexities of force and velocity interpolation in a 3D domain.
- Advanced Implementation: The implementation includes features like creating a list of neighboring cells to optimize the force spreading and interpolation steps.
Technical Details
- Fluid Solver: OpenFOAM (modified
icoFoam) - Solid Solver: Custom Fortran-based 3D solver
- Coupling Method: Immersed Boundary Method (Continuous Forcing)
- Core Components:
icoFoam.C: Modified main solver file.createFields.H: Modified to include the IBM force field.fem3d.f90: Fortran source code for the 3D solid solver.soft_particles.f90: Fortran source for the interface between OpenFOAM and the solid solver.
Implementation Highlights
The implementation involves modifying the momentum predictor step in the icoFoam solver to include a source term representing the force exerted by the immersed boundary. A shared library is created from the Fortran code, which is then linked with the OpenFOAM solver. The communication between the two solvers is handled by a set of Fortran subroutines that exchange position, force, and velocity data. The code is still under development, with opportunities for improvement in efficiency and accuracy.