Anaerobic Biogas Digester Modelling
Using OpenFOAM and Fluent
Andrew CoughtrieCivil Engineering
Biogas Digestion?
Problem Definition• Waste Treatment
• Mixing effectiveness
• Failure when scaled up
• Difficult to monitor experimentally
* Karim k. et al. [2007] Gas-lift Digester Configuration Effects on Mixing Effectiveness
Experimental bench scale internal airlift loop biogas digester.*
CFD• Structured square mesh• Ansys Meshing and
BlockMesh• Approximation for inlet
boundaryInlet
Slurry Surface
Outlet
Walls
Problem Setup• Inlet boundary condition based on approximation of flow
velocity• RNG k-epsilon turbulence model
• Zero shear wall at surface
OpenFOAM Control
Function to monitor velocity
Discretisation Schemes
Linear solver
Fluent Wall TreatmentStandard Wall
FunctionsScalable Wall
FunctionsEnhanced Wall
Treatment
Fluent vs. OpenFOAM
OpenFOAM Fluent
*Karim k. et al. [2004] Flow Pattern Visualization of a Simulated Digester
OpenFOAM Fluent Experimental*
Single-phase vs. Multiphase
DPM Single-Phase
Ongoing Work
• Non-Newtonian fluid modelling
• Comparison between single and multiphase for OpenFOAM and Fluent
• Multiphase 3D modelling
• Euler-Euler Multiphase using OpenFOAM
Three-Dimensional
• Full 3D geometry for DPM
• Import mesh to OpenFOAM for use with bubbleFoam
?Questions?