09:15 〜 09:30
[SEM33-02] メッシュレス粒子法を用いたMT法3次元フォワード計算
キーワード：粒子法, MT法, フォワード計算, 数値計算, メッシュレス
Accurate forward calculation of electromagnetic induction in the earth is essential for quantitative modeling of subsurface resistivity structure. The expression of complicated topography and bathymetry in the three-dimensional (3D) model should be carefully handled for accurate numerical calculations, but frequently ignored, unfortunately. For example, a widely-used 3D inversion code of magnetotelluric (MT) data is based on the finite difference method (FDM), in which the 3D model consists of assembly of rectangular blocks. Therefore, a smooth relief on the ground can be expressed as stair-like hills and valleys. Previous studies indicated that such step-wise approximation of topography yields large calculation error of MT responses. The finite element method (FEM) can include the smooth topographic relief in the 3D model, while the selection of proper mesh configuration for FEM is a hard task for users.
In this research, I developed an new 3D MT forward calculation method with
with MPS(Moving Particle Semi-implicit) method, one of the mesh-free calculation methos. The main purpose is the proper expression of topography / bathymetry in the 3D resistivity model. The MPS method is a particle method and is developed for the simulation of incompressible flow by Koshizuka and Oka (1996), and has been tried to apply for the one-dimensinal and two-dimensional MT problems. I use the MPS method for the 3D simulation of electromagnetic induction in this study. In the forward calculation, electric field and magnetic field are defined at each particle in a calculation model. MT responses are then calculated on an arbitrary point (on the surface, on the seafloor, and even in the earth). The results of MT forward calculation indicate enough accuracy and capability to calculate MT responses with complicated topography.
In this research, I developed an new 3D MT forward calculation method with
with MPS(Moving Particle Semi-implicit) method, one of the mesh-free calculation methos. The main purpose is the proper expression of topography / bathymetry in the 3D resistivity model. The MPS method is a particle method and is developed for the simulation of incompressible flow by Koshizuka and Oka (1996), and has been tried to apply for the one-dimensinal and two-dimensional MT problems. I use the MPS method for the 3D simulation of electromagnetic induction in this study. In the forward calculation, electric field and magnetic field are defined at each particle in a calculation model. MT responses are then calculated on an arbitrary point (on the surface, on the seafloor, and even in the earth). The results of MT forward calculation indicate enough accuracy and capability to calculate MT responses with complicated topography.