## Solver: rhoReactingFoam Description

rhoReactingFoam is a solver designed for transient simulations of compressible, reacting flows. This solver is particularly tailored for simulating combustion processes and chemical reactions within a compressible flow regime. It handles laminar and turbulent, multicomponent (mixture) flows with temperature and density variations (it solves the energy equation). The solver is well-suited for the simulation of combustion processes and chemical reactions within fluids, accommodating a variety of reaction kinetics and species transport mechanisms.

The solver is similar to reactingFoam with the difference in thermophysical model. reactingFoam is based on compressibility \(\psi\), while `rhoReactingFoam`

is based on density for calculations of thermophysical properties. The thermodynamic models represent, how to handle the relationship between pressure, density, and temperature in the context of reacting flows.

When using compressibility-based thermophysical models, density is derived from pressure and compressibility \(\rho = p \psi\), making it particularly useful for flows where compressibility effects are dominant. `rhoReactingFoam`

directly uses density for calculations, which makes it applicable for situations where density changes are mostly due to temperature variation. However, it’s also suitable for compressible flows, including transonic situations.

The solver uses the PIMPLE (merged PISO-SIMPLE) algorithm for pressure-momentum coupling, which leverages the strengths of both PISO and SIMPLE methods for pressure-velocity coupling, ensuring robustness in handling transient flows with large time steps. It enables adaptive adjustment of time step size within different regions by Local Time Stepping (LTS) functionality. It also supports Multiple Reference Frame (MRF), porosity modeling and allows easy integration of passive scalar transport equations and source terms.

The solver is mainly used for the analysis of burners in the energy industry and in environmental engineering for pollution modeling and control.

## Solver: rhoReactingFoam Features

**Transient****Compressible****Single-Phase**

- Species Transport
- Chemical Reactions
- Combustion Modeling

- Laminar and Turbulent (RANS, LES, DES)
- Multicomponent (mixture)
- Perfect Gas Model
- Pressure-Based Solver
- Rotating Objects:
- Multiple Reference Frames (MRF)

- Passive Scalar
- Porosity Modeling
- Heat Transfer
- Heat Source
- Source Term (explicit/implicit)
- Transonic Flow
- PIMPLE Algorithm
- Solution Limiters:
- Velocity Damping
- Pressure Limit
- Temperature Limit

## Solver: rhoReactingFoam Application

**Energy:**

- Burners
- Combustion Chambers
- Pollution Modelling

## Solver: rhoReactingFoam Species & Reactions Solvers Comparison

Species & Reactions Solvers In this group, we have included compressible (pressure-based) solvers that can be used to simulate: **Species Transport**, **Multicomponent Gas Mixtures**, **Chemical Reactions**, **Combustion**.

**Multicomponent**

- simpleReactingParcelFoam steady-state, multiphase particle clouds
- reactingParcelFoam transient, multiphase particle clouds

**Spray**

- sprayFoam transient, liquid particles only, dedicated to fuel spray combustion
- sprayDyMFoam extension of sprayFoam with DyM

**Coal**

- simpleCoalParcelFoam steady-state, coal particles only
- coalChemistryFoam transient, coal particles only

**Gas***

- reactingFoam fluids with minor density fluctuations (caused by pressure variance), no buoyancy
- rhoReactingFoam fluids with density variations due to reactions, no buoyancy
- rhoReactingBuoyantFoam extension of rhoReactingFoam with buoyancy forces

- * All solvers in this group are transient

- DyM - Dynamic Mesh

## Solver: rhoReactingFoam 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 | \(U\) [\(\frac{m}{s}\)] |

Temperature | \(T\) [\(K\)] |

Species Mass Fraction | \(Y_i\) [\(-\)] |

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

**Derivative Results**

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

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

Mach Number | \(Ma\) [\(-\)] |

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 | \(WSS\) [\(Pa\)] |

Wall Heat Flux | \(\phi_q\) [\(W/m^2\)] |

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 | \(Avg\) \(Min\) \(Max\) |