What we can help you with
Injecting fluid into or withdrawing it from a porous material changes the pressure and can cause deformation. This deformation can, in turn, affect pore volume, permeability and subsequent flow. Poromechanical models describe these interactions.
We can help you:
- Develop models that couple fluid flow and mechanical deformation.
- Implement poromechanics in existing simulation tools.
- Select and adapt discretisations for complex geometries and heterogeneous materials.
- Develop stable and efficient coupling strategies and numerical solvers.
- Investigate how model assumptions and numerical choices affect the results.
Do you need to couple flow and mechanics in a model or simulator? Contact our Applied Computational Science research group.
The interaction between pore pressure and deformation
Poromechanics combines a description of the solid material's mechanical response with a description of the fluids in its pores. Pore pressure enters the relationship between loading and deformation, while changes in pore volume enter the fluid mass balance. Depending on the material model, flow properties may also change as the material deforms.
Linear poroelasticity provides an important starting point when deformations are small and the material response can be described as elastic. The validity of the model must be assessed against the loading conditions and processes of interest. Multiphase flow, temperature changes or more complex constitutive behaviour may require an extended formulation.
Quasi-static models neglect mechanical inertia, while pressure and flow still evolve over time. Dynamic models include inertia and are relevant when processes such as wave propagation need to be represented.
Coupled computations and solution strategies
Flow and mechanics can be solved together as a single coupled equation system or sequentially, with separate solvers exchanging information. The choice affects stability, computational cost and the scope for reusing existing software.
We work on how these interactions should be represented and solved numerically. Sequential approaches require control of the coupling error and the iterations between subproblems. For a monolithic approach, the structure of the coupled equation system must be exploited to achieve efficient and robust computations.
We consider coupling strategies, time stepping and solver tolerances together, particularly when pressure changes and the mechanical response are strongly coupled.
Discretisation on complex grids
Flow and mechanics place different demands on the discretisation. An effective coupling must respect both fluid mass balance and mechanical equilibrium. Strong material contrasts, anisotropy and irregular cells can make this challenging.
We develop methods for unstructured and general polyhedral grids, emphasising consistency, stability and practical implementation. When the submodels use different representations, transferring pressure, deformation and other coupling quantities must also be treated as part of the numerical method.
From method development to applications
Our work draws on experience in both simulator development and numerical methods for flow and mechanics. We can contribute individual computational components or develop an integrated poromechanical model.
Subsurface applications include pressure changes during injection and production, compaction, and deformation associated with storage and energy recovery. Read more about our broader expertise in geomechanical modelling and flow in porous media.
The methods are also relevant to other porous materials. Model selection and constitutive descriptions must then be adapted to the application in collaboration with specialists who understand the material and the processes involved.