## Solver: driftFluxFoam Description

driftFluxFoam is a solver designed for the transient simulation of two incompressible fluids. It utilizes a mixture methodology and incorporates the drift-flux approximation to depict the relative motion between the phases.

It is particularly suited for simulations involving the settling of the dispersed phase and addressing various other separation-related challenges. This solver is designed to simulate multiphase flow, particularly for scenarios where there are two immiscible and incompressible fluid phases, with one phase dispersed in the other, like bubbles in the liquid. Originally it was designed for sediment flows, where liquid was the continuous phase, and solid particles the dispersed phase. However, the implementation does not limit the solver only to solid particles. Gas, liquids, and solids can be modeled as a dispersed phase.

The **PIMPLE** (merged **PISO-SIMPLE**) algorithm is used 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. Additionally, the solver can include porosity, buoyancy, and MRF (Multiple Reference Frame) features in the flow simulation.

Due to its specialized features, the solver can be used in water management problems for simulating the water purifiers, or sedimentation process in rivers or tanks. In the HVAC (Heating, Ventilation, and Air Conditioning) industry, it can be used for simulating dust particles in air (filtration systems).

## Solver: driftFluxFoam Features

**Transient****Incompressible****Multiphase - Dispersed Phase (Drift Flux)**

- 1 Fluid and Slurry or Plastic Dispersed Phase
- Drift Flux Approximation

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

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

## Solver: driftFluxFoam Application

**Water Management**

- Water Purifiers
- River Sediment
- Sedimentation Tank (Water Treatment Plant)

**HVAC**

- Dust Particles in Air (Filtration Systems)

**Chemical**

- Bubble Column Reactor

## Solver: driftFluxFoam Multiphase - Dispersed Solvers Comparison

Dispersed Solvers In this group, we have included solvers implementing the **Eulerian** or **Lagrangian** approach to handle multiple fluids and particle clouds considering **Dispersed Phases** or **Fluid-Particle interactions**.

**Dispersed - Euler**

- multiphaseEulerFoam multiple miscible fluids, Euler-Euler approach

**Dispersed - Lagrangian**

- DPMDyMFoam extension of DPMFoam with DyM
- MPPICDyMFoam extension of MPPICFoam with DyM

**Dispersed - Drift-Flux**

- driftFluxFoam 1 fluid and slurry or plastic dispersed phase, drift flux approximation for relative phase motion

- DPM - Discrete Phase Model
- MP-PIC - multiphase particle-in-cell method
- DyM - Dynamic Mesh

## Solver: driftFluxFoam Alternative Solvers

In this section, we propose alternative solvers from different categories, distinct from the current solver. While they may fulfill similar purposes, they diverge significantly in approach and certain features.

- interFoam base version of
`driftFluxFoam`

, 2 immiscible fluids, VoF approach

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