## Solver: rhoReactingBuoyantFoam Description

rhoReactingBuoyantFoam is a solver designed for the transient simulations of compressible, reacting flows with an enhanced treatment of buoyancy forces. This solver is specifically tailored for simulating combustion processes and chemical reactions within compressible flow regimes. It can handle both laminar and turbulent, multicomponent (mixture) flows, accounting for variations in temperature and density by solving the energy equation. The solver is particularly well-suited for the simulation of combustion processes and chemical reactions in fluids, accommodating various reaction kinetics and species transport mechanisms.

This solver is analogous to rhoReactingFoam, with the addition of a buoyancy force term in the equations of motion. Both solvers base their calculations of thermophysical properties on density. The thermodynamic models within the solver describe how to manage the relationship between pressure, density, and temperature in the context of reacting flows.

'rhoReactingBuoyantFoam' uses density for its calculations, making it suitable for situations where density changes are primarily due to temperature variations. However, it is also capable of handling compressible flows, including those in transonic conditions.

The solver employs the **PIMPLE** algorithm, a merged **PISO-SIMPLE** approach, for pressure-momentum coupling. This method combines the strengths of both the PISO and SIMPLE methods for pressure-velocity coupling, ensuring robustness in handling transient flows with large time steps. It features adaptive time step size adjustment within different regions through **Local Time Stepping (LTS)** functionality. Moreover, it supports **Multiple Reference Frames (MRF)**, porosity modeling, and allows for the easy integration of passive scalar transport equations and source terms.

The enhanced buoyancy treatment makes the solver particularly suitable for analyzing combustion processes and reacting flows where buoyancy plays a crucial role. It is applicable for the analysis of burners or engines, furnaces, and enclosed spaces, where buoyancy effects due to temperature gradients significantly influence flow and reaction patterns.

## Solver: rhoReactingBuoyantFoam Features

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

- Species Transport
- Chemical Reactions
- Combustion Modeling
- Buoyancy

- 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: rhoReactingBuoyantFoam Application

**Energy:**

- Burners
- Combustion Chambers
- Pollution Modelling

**Automotive Industry:**

- Engines

**Chemical Industry**

- Reactors where Exothermic or Endothermic Reactions Are Coupled with Fluid Flow
- Chemical Process Engineering: In Reactors Where Exothermic or Endothermic Reactions Are Coupled with Fluid Flow, Affecting the Density and Thereby the Flow Patterns due to Buoyancy.

## Solver: rhoReactingBuoyantFoam 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: rhoReactingBuoyantFoam 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 | \(p\) [\(Pa\)] |

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**

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