# Incompressible Solvers - Comparison

Source: https://help.sim-flow.com/solvers/incompressible-solvers-comparison
Last updated: 2024-02-21

## Incompressible Solvers

Incompressible Solvers In this group, we have included single-phase, pressure-based solvers for **low-speed flows** with negligible variations in density, applicable for **external** and **internal aerodynamics** (**Ma < 0.3**) and **hydrodynamics**. These solvers use incompressibility features for stability and robustness.

**Incompressible, Steady-State - Main Solvers**

- [simpleFoam](https://help.sim-flow.com/solvers/simple-foam) steady-state, SIMPLE algorithm
- [overSimpleFoam](https://help.sim-flow.com/solvers/over-simple-foam) extension of simpleFoam with Overset
- [SRFSimpleFoam](https://help.sim-flow.com/solvers/srf-simple-foam) variant of simpleFoam resolved in SRF

**Incompressible, Transient - Main Solvers**

- [pimpleFoam](https://help.sim-flow.com/solvers/pimple-foam) transient, PIMPLE algorithm, DyM
- [overPimpleDyMFoam](https://help.sim-flow.com/solvers/over-pimple-dym-foam) extension of pimpleFoam with Overset, DyM
- [SRFPimpleFoam](https://help.sim-flow.com/solvers/srf-pimple-foam) variant of pimpleFoam resolved in SRF

**Incompressible, Transient - Simplified Solvers***

- [pisoFoam](https://help.sim-flow.com/solvers/piso-foam) transient, PISO** algorithm
- [icoFoam](https://help.sim-flow.com/solvers/ico-foam) transient, PISO** algorithm, laminar flows only (no turbulence), Newtonian fluids only

- * Dedicated solvers for simplified scenarios, improve stability and computational efficiency
- ** The PISO algorithm is used for cases with a small Courant number Co < 1

- DyM - Dynamic Mesh
- MRF - Multiple Reference Frame
- SRF - Single Reference Frame
- Overset - also known as Chimera Grid (Method)
- SIMPLE - Semi-Implicit Method for Pressure-Linked Equations
- PIMPLE - merged PISO and SIMPLE
- PISO - Pressure-Implicit Split-Operator

Additionally, these solvers (except icoFoam) support:

- Newtonian and non-Newtonian fluid models
- RANS/LES turbulence models
- Porosity models
- MRF, or SRF (depending on the solver variant)
- Passive scalar
- Custom source term