## Solver: interPhaseChangeFoam Description

interPhaseChangeFoam is a solver designed for transient simulations of two incompressible, isothermal, and immiscible fluids undergoing phase change processes, such as cavitation. It handles laminar and turbulent, accommodating both Newtonian and non-Newtonian fluids. It utilizes the Volume of Fluid (VoF) approach for capturing the interface between the fluids accurately. This solver extends the capabilities of interFoam by incorporating phase-change models, which are primarily designed to simulate cavitation but are versatile enough to support other phase-change mechanisms.

The solver uses the **PIMPLE** (merged **PISO-SIMPLE**) algorithm for pressure-momentum coupling. This algorithm leverages the strengths of both PISO and SIMPLE methods for pressure-velocity coupling, ensuring robustness in handling transient flows with large time steps. This approach is supplemented by under-relaxation techniques to secure convergence stability. It supports Multiple Reference Frame (MRF) and porosity modeling and allows easy integration of passive scalar transport equations and source terms.

The ability to capture phase changes makes the solver useful in such scenarios as cavitation around hydrofoils, propellers, and hydraulic pumps. In the piping industry, the solver can be used to predict cavitation in pipe systems and valves.

## Solver: interPhaseChangeFoam Features

**Transient****Incompressible****Multiphase - Volume of Fluid (VoF)**

- 2 Immiscible Fluids (Liquid & Vapor)
- Cavitation
- Phase Change Models:
**Schnerr-Sauer**Merkle **Kunz

- Laminar and Turbulent (RANS, LES, DES)
- Newtonian and Non-Newtonian Fluid
- Pressure-Based Solver
- Rotating Objects:
- Multiple Reference Frames (MRF)

- Passive Scalar
- Porosity Modeling
- Buoyancy
- Source Term (explicit/implicit)
- PIMPLE Algorithm
- MULES Algorithm
- Solution Limiters:
- Velocity Damping

## Solver: interPhaseChangeFoam Application

**Marine**

- Cavitation around Hydrofoils or Propellers

**Rotating Machines**

- Cavitation in Hydraulic Pump

**Piping**

- Cavitation in Pipe Systems or Valves
- Boiling in a Pipe

**Heat Exchangers**

- Boiling Heat Transfer and Phase Interaction in Heat Exchanger, Nuclear Reactors
- Evaporation in Heat and Mass Exchangers

## Solver: interPhaseChangeFoam Multiphase - Phase Change Solvers Comparison

Phase Change Solvers In this group, we have included solvers implementing **Phase Change** models to handle cavitation, and surface evaporation/condensation (liquid and its vapor phases).

**Phase Change - Cavitation**

- cavitatingFoam 2 immiscible fluids, dedicated to cavitation, Homogeneous Equilibrium Model (HEM)
- interPhaseChangeFoam 2 immiscible fluids, dedicated to cavitation, VoF, Phase Change Models: Schnerr-Sauer, Merkle, Kunz

- cavitatingDyMFoam extension of cavitatingFoam with DyM
- interPhaseChangeDyMFoam extension of interPhaseChangeFoam with DyM
- overInterPhaseChangeDyMFoam extension of interPhaseChangeFoam with Overset, DyM

**Phase Change - Condensation / Evaporation**

- interCondensatingEvaporatingFoam 2 immiscible fluids, phase changes (evaporation and condensation) between a fluid and its vapor phase

- VoF - Volume of Fluid
- DyM - Dynamic Mesh
- Overset - also known as Chimera Grid (Method)

## Solver: interPhaseChangeFoam Results Fields

This solver provides the following results fields:

**Primary Results Fields**- quantities produced by the solver as default outputs**Derivative Results**- quantities that can be computed based on primary results and supplementary models. They are not initially produced by the solver as default outputs.

**Primary Results Fields**

Velocity | \(U\) [\(\frac{m}{s}\)] |

Phase Volume Fraction | \(\alpha\) [\(-\)] |

Hydrostatic Perturbation Pressure | \(p - \rho gh\) [\(Pa\)] |

**Hydrostatic Perturbation Pressure** This value represents the pressure without the hydrostatic component (minus gravitational potential). Read More: Hydrostatic Pressure Effects

**Derivative Results**

Pressure | \(P\) [\(Pa\)] |

Density | \(\rho\) [\(\frac{kg}{m^{3}}\)] |

Vorticity | \(\omega\) [\(\frac{1}{s}\)] |

Courant Number | \(Co\) [\(-\)] |

Peclet Number | \(Pe\) [\(-\)] |

Stream Function | \(\psi\) [\(\frac{m^2}{s}\)] |

Q Criterion | \(Q\) [\(-\)] |

Wall Functions (for RANS/LES turbulence) | \(y^+\) [\(-\)] |

Wall Shear Stress | \(WSS\) [\(Pa\)] |

Turbulent Fields (for RANS/LES turbulence) | \(k\) \(\epsilon\) \(\omega\) \(R\) \(L\) \(I\) \(\nu_t\) \(\alpha_t\) |

Volumetric Stream | \(\phi\) [\(\frac{m^{3}}{s}\)] |

Passive Scalar | \(scalar_i\) [\(-\)] |

Forces and Torque acting on the Boundary | \(F\) [\(N\)] \(M\) [\(-\)] |

Force Coefficients | \(C_l\) [\(-\)] \(C_d\) [\(-\)] \(C_m\) [\(-\)] |

Average, Minimum or Maximum in Volume from any Result Field | \(Avg\) \(Min\) \(Max\) |