Transient electromagnetic three-dimensional FDTD forward modeling multi-resolution mesh division method

Abstract

The invention discloses a transient electromagnetic three-dimensional FDTD forward modeling multi-resolution mesh division method, which comprises the steps of: using coarse meshes for division; establishing an FDTD three-dimensional forward model; carrying out local-refinement division on parts requiring attention of the model, so as to form fine meshes, thus a calculation region of the entire model at least comprises two sets of meshes used for describing a target with dimensional difference exceeding a preset value; determining electric field and magnetic field components in the fine meshesbased on a Maxwell equation set; determining and updating boundary conditions of the coarse and fine meshes based on a diffusion and propagation time sequence of the electromagnetic fields; and unifying the coarse and fine meshes in time and space domains. The transient electromagnetic three-dimensional FDTD forward modeling multi-resolution mesh division method reduces the number of coarse meshes, greatly shortens the time of a single iteration naturally, and further shortens the overall calculation time.

Description

technical field [0001] The invention relates to a transient electromagnetic three-dimensional FDTD forward modeling multi-resolution grid division method. Background technique [0002] Transient Electromagnetic (TEM) or Time Domain Electromagnetic (TDEM) methods are based on the difference in resistivity of the detection target and rely on Electromagnetic Induction (EMI) signals to achieve detection, which is a low-cost, high-efficiency, The geophysical detection method with simple construction and high precision has been used in metal mineral resource exploration, marine gas hydrate detection, environmental and hydrogeological investigation, groundwater assessment and monitoring, mining goaf and disaster water source detection, underground unexploded ordnance ( Unexploded Ordnance (UXO) exploration, geological mapping and other application fields have played an important role. With the rapid development of economy and society, more and more exploration needs to be carried ...

AI Technical Summary

Problems solved by technology

The main contradiction of transient electromagnetic 3D FDTD forward modeling grid generation is the minimum grid size. If the target is small, a small grid must be used to build the abnormal body, and the minimum grid size is related to the time sampling step Closely related, when the minimum grid size setting is small, in order to ensure sufficient model calculation area, a larger number of grids must be used for subdivision modeling, and the time grid will also be affected by the minimum grid size; When the minimum grid size is larger, fewer grid numbers and larger time steps can be used, but the detailed description of abnormal targets will be greatly reduced.

Images