# interFoam

Source: https://help.sim-flow.com/solvers/inter-foam
Last updated: 2026-10-14

## Description

interFoam is a solver designed for transient simulations of two incompressible, isothermal, and immiscible fluids. It handles laminar and turbulent flows, accommodating both Newtonian and non-Newtonian fluids. It utilizes the Volume of Fluid (VoF) approach for capturing the interface between the fluids accurately. The solver is suited to cases where the particular interest is in the behavior of the interface between two fluids (e.g. water and air).

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 Frames (MRF) and porosity modeling and allows easy integration of passive scalar transport equations and source terms. The solver handles dynamic meshes.

The ability to capture complex fluid interactions together with dynamic mesh capabilities makes it very versatile and useful in the marine industry, where complex ship-wave interactions can be studied. For the transportation industry, mixing in stirring tanks can be analyzed and tank sloshing phenomena. Wave loading or offshore structure loads can be predicted.

## Features

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

- 2 Immiscible Fluids
- Dynamic Mesh Motion

- 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

## Application

**Marine Industry**

- Planing Ship Hulls & Ship Motion (e.g. [Ship hull](https://help.sim-flow.com/tutorials/ship-hull))
- Propeller Performance
- Sloshing in Tanks (e.g. [Sloshing Tank](https://help.sim-flow.com/tutorials/sloshing-tank))
- Ship Motion under Different Conditions with Dynamic Mesh Feature
- Offshore Structures Loads
- Calm-water Air Gap under Offshore Platform Decks
- Wave Loading on Profiles
- Floating Objects
  - Wave Energy Absorbers
  - Point Absorbers

**Dams & Spillways**

- Spillway Analysis
- Fishways Designing
- Weir Flows
- Dam Break Scenarios (e.g. [Dam break](https://help.sim-flow.com/tutorials/dam-break))
- Hydro Plants
- Hydraulic Energy Losses Predictions
- Pipe and Channel Flows

**Automotive industry**

- Sloshing Effects in Tanks (e.g. [Sloshing Tank](https://help.sim-flow.com/tutorials/sloshing-tank))
- Fuel Level Indication with Moving Objects 6 DoF (Six Degrees of Freedom) Model

**Aerospace Industry**

- Sloshing Effects in Fuel Tanks

**Chemistry and Biotechnology**

- Active Mixers with Mechanical Devices to Facilitate Mixing (e.g. [Mixing tank](https://help.sim-flow.com/tutorials/mixing-tank))
- Static Mixers

**Injection Molding**

- Simplified Injection Molding Process with non-Newtonian Fluids (e.g. [Injection Molding](https://help.sim-flow.com/tutorials/injection-molding))

**Rotating Machinery**

- Turbines, Industrial Mixers, Stirred Tank Reactors
- Pumps, Valves, Hydraulic Turbines
- Marine Propellers (e.g. [Propeller](https://help.sim-flow.com/tutorials/propeller))

## Multiphase - Free Surface (VoF) Solvers

Free Surface (VoF) Solvers In this group, we have included solvers implementing the **Volume of Fluid (VoF)** approach to handle multiple immiscible and miscible fluids and interactions between them.

**Free Surface (VoF) - Immiscible**

- [interFoam](https://help.sim-flow.com/solvers/inter-foam) 2 immiscible fluids, DyM
- [multiphaseInterFoam](https://help.sim-flow.com/solvers/multiphase-inter-foam) multiple immiscible fluids, DyM
- [interIsoFoam*](https://help.sim-flow.com/solvers/inter-iso-foam) 2 immiscible fluids, isoAdvector* method, DyM

- [overInterDyMFoam](https://help.sim-flow.com/solvers/over-inter-dym-foam) extension of interFoam with Overset, DyM
- [compressibleInterFoam](https://help.sim-flow.com/solvers/compressible-inter-foam) compressible version of interFoam with heat transfer
- [compressibleInterDyMFoam](https://help.sim-flow.com/solvers/compressible-inter-dym-foam) compressible version of interFoam with heat transfer and DyM

**Free Surface (VoF) - Miscible**

- [interMixingFoam](https://help.sim-flow.com/solvers/inter-mixing-foam) 3 fluids (2 miscible and 1 immiscible), DyM
- [twoLiquidMixingFoam**](https://help.sim-flow.com/solvers/two-liquid-mixing-foam) 2 miscible fluids

- * isoAdvector - an alternative approach for interface capturing, MULES method used in other VoF solvers
- ** Solver designed to handle mixtures consisting of multiple fluids within the same phase, such as two gases or two liquids

- VoF - Volume of Fluid
- DyM - Dynamic Mesh
- Overset - also known as Chimera Grid (Method)

## 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.

- [interMixingFoam](https://help.sim-flow.com/solvers/inter-mixing-foam) variant of `interFoam`, 3 fluids (2 miscible and 1 immiscible)
- [twoLiquidMixingFoam](https://help.sim-flow.com/solvers/two-liquid-mixing-foam) variant of `interFoam`, 2 miscible fluids
- [driftFluxFoam](https://help.sim-flow.com/solvers/drift-flux-foam) variant of `interFoam`, 1 fluid and slurry or plastic dispersed phase, drift flux approximation for relative phase motion

## Tutorial

**[Droplet](https://help.sim-flow.com/tutorials/droplet)**

- Introduction to SimFlow, covering multiphase and incompressible 2D flow. The simulation showcases a free-falling water droplet into a tank.

**[Ship Hull](https://help.sim-flow.com/tutorials/ship-hull)**

- Two-phase flow simulation with dynamic mesh motion, involving the 6DoF motion of a ship hull floating on a water surface, influenced by buoyancy forces.

**[Dam Break](https://help.sim-flow.com/tutorials/dam-break)**

- Free surface flow using a Volume of Fluid (VoF) approach, analyzing the water flow through a dam.

**[Sloshing Tank](https://help.sim-flow.com/tutorials/sloshing-tank)**

- Water sloshing inside a braking cistern analysis, driven by inertial forces. The tutorial simulates rigid body motion.

**[Mixing and Stirring Tank](https://help.sim-flow.com/tutorials/mixing-tank)**

- Analysis with Dynamic Mesh for modeling rotating components, simulating the rotation of an impeller in a partially filled cylindrical tank.

**[Injection Molding](https://help.sim-flow.com/tutorials/injection-molding)**

- Simulation of the injection molding process using the Power Law transport model, filling a housing with melted plastic.

## Validation Cases

**[Wave Impact in Rectangular Tank](https://help.sim-flow.com/validation/wave-impact)**

- Wave impact simulation in a narrow, rectangular tank, where assumed tank motion induces sloshing within.

## 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](https://doc.openfoam.com/2312/tools/processing/solvers/algorithm-p-rgh)

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