OpenFOAM Multiphase Flow Analysis

Analyzes free surface, dispersed systems, and reactive multiphase flows using solvers like interFoam (VOF Method), multiphaseInterFoam, reactingMultiphaseEulerFoam, etc. Interface capturing via the MULES algorithm.

Expressing this with equations, it looks like this.

CSF model for surface tension:

The numerical methods for OpenFOAM multiphase flow analysis are based on the Finite Volume Method (FVM) or the Finite Element Method (FEM). Being open source, its greatest advantage is the ability to verify and modify algorithm details at the source code level. Discretization schemes and convergence criteria logic, which are black boxes in commercial solvers, can be directly examined, making it particularly suitable for academic research and method development. Continuous improvement and bug fixes by the community ensure quality.

Explains the theoretical foundation of numerical methods implemented by open-source CAE tools.

The principle of minimum potential energy, fundamental to structural analysis:

The displacement field $\mathbf{u}$ that makes $\Pi$ stationary is the equilibrium solution. CalculiX and Code_Aster implement the Galerkin method based on this variational principle.

The FVM adopted by OpenFOAM is based on the integral conservation law for a control volume:

Discrete equations are obtained by applying this integral form to each control volume and numerically evaluating the fluxes on the faces.

Open-source CAE allows third-party verification of algorithms because the source code is public. On the other hand, there is no vendor support like with commercial tools, making information sharing within user communities and forums crucial.

• Results from OSS tools should always be validated against known benchmark problems.
• Be aware of version incompatibilities (especially differences between OpenFOAM forks).
• It is recommended to verify OSS accuracy by comparing results with commercial tools.
• When documentation is lacking, direct reference to the source code may be necessary.

Understanding the dimensionless parameters governing the physical phenomenon being analyzed is fundamental to appropriate model selection and parameter setting.

• Peclet Number Pe: Relative importance of convection vs. diffusion. Pe >> 1 indicates convection dominance (stabilization techniques required).
• Reynolds Number Re: Ratio of inertial to viscous forces. Fundamental parameter for fluid problems.
• Biot Number Bi: Ratio of internal conduction to surface convection. Bi < 0.1 allows application of the lumped capacitance method.
• Courant Number CFL: Indicator of numerical stability. Explicit methods require CFL ≤ 1.

Dimensional analysis based on Buckingham's Π theorem is effective for order-of-magnitude estimation of analysis results. Using characteristic length $L$, characteristic velocity $U$, and characteristic time $T = L/U$, estimate the order of each physical quantity beforehand to confirm the validity of the analysis results.

Choosing appropriate boundary conditions is directly linked to solution uniqueness and physical validity. Insufficient boundary conditions lead to an ill-posed problem, while excessive ones cause contradictions.

Yeah, you're doing great! Actually getting hands-on is the best way to learn. If you don't understand something, feel free to ask anytime.

Explains key points of numerical methods and implementation for OpenFOAM multiphase flow analysis.

Building from source code uses CMake or dedicated build systems (like OpenFOAM's wmake). Proper version management of dependency libraries (MPI, PETSc, BLAS/LAPACK, etc.) is crucial. Linux environments are recommended, but using WSL2 or Docker containers makes it possible on Windows as well.