## Solver: overInterPhaseChangeDyMFoam Description

overInterPhaseChangeDyMFoam 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 interPhaseChangeFoam and enhances its predecessor’s capabilities by incorporating overset (Chimera) meshes. This advancement makes the solver particularly suitable for scenarios involving significant object motion, where traditional dynamic meshes prove inadequate. The overset framework offers a universal approach to implementing overset meshes for both stationary and dynamic scenarios. It utilizes mappings from cell to cell across various, separate mesh regions to create a unified domain. This approach facilitates intricate mesh movements and interactions without the drawbacks typical of mesh deformation, accommodating both single-phase and multiphase flows.

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 together with overset meshes, makes the solver useful in such scenarios as cavitation around rotating propellers.

## Solver: overInterPhaseChangeDyMFoam Features

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

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

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

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

## Solver: overInterPhaseChangeDyMFoam Application

**Marine**

- Cavitation around Rotating Propellers

**Rotating Machines**

- Cavitation in Hydraulic Pump

## Solver: overInterPhaseChangeDyMFoam 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: overInterPhaseChangeDyMFoam 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 | \(Avg\) \(Min\) \(Max\) |