What is it about?

I've developed a new technique that consists of the finite-difference (FD) and finite-elements (FE) numerical technique to obtain the forward modeling response of a 3D Magnetotelluric problem. The newly developed approach is almost as fast as the pure FD and it can also represent the topographic features as easily as the FE method.

Featured Image

Why is it important?

While it is easier to employ the finite-difference (FD) technique to a given problem, it is an overburden to represent a topographic feature with this numerical technique. While it is easier to represent the topographic features with the finite-elements (FE) technique, it is slower to solve the linear system arising from FE discretization. That is why, in this study, a structured mesh is picked and the some parts of the mesh are distorted to represent the topographic features. After that, the FD method is used on the non-distorted part of the mesh while the distorted parts of it are handled with the FE numerical technique. This study is the first hybrid FE-FD technique for the 3D Magnetotelluric forward modeling in frequency domain.

Perspectives

This study is mainly performed for the acceleration of the 3D inversion of Magnetotelluric data. A fast forward modeling routine is essential for an inversion algorithm. It is known that the finite-difference algorithm is easily deployable and fast to solve, while the finite-elements method is great for distorted meshes and thus for the models with topography. In the new algorithm, a distorted but structured mesh is used for the forward modeling. On the non-distorted parts of it, the FD method is deployed and oppositely, on the distorted regions, the FE technique is considered. This simple technique resulted in twice speed-up for the models used in this study. It is also found out that, the hybrid technique consumes significantly less computer memory than the FE method which can be important when a limited memory system (i.e, GPU) is considered for the solution of the linear systems.

Deniz Varilsuha
Istanbul Teknik Universitesi

Read the Original

This page is a summary of: A Hybrid Finite Difference Finite Element Approach for 3D Magnetotelluric Forward Modeling, June 2018, EAGE Publications,
DOI: 10.3997/2214-4609.201801208.
You can read the full text:

Read

Resources

Contributors

The following have contributed to this page