# SimPEG.electromagnetics.natural_source.Simulation3DPrimarySecondary#

class SimPEG.electromagnetics.natural_source.Simulation3DPrimarySecondary(mesh, survey=None, sigmaPrimary=None, **kwargs)[source]#

A NSEM problem solving a e formulation and a primary/secondary fields decompostion.

By eliminating the magnetic flux density using

$\mathbf{b} = \frac{1}{i \omega}\left(-\mathbf{C} \mathbf{e} \right)$

we can write Maxwell’s equations as a second order system in $$\mathbf{e}$$ only:

$\left[\mathbf{C}^{\top} \mathbf{M_{\mu^{-1}}^f} \mathbf{C} + i \omega \mathbf{M_{\sigma}^e} \right] \mathbf{e}_{s} = i \omega \mathbf{M_{\sigma_{p}}^e} \mathbf{e}_{p}$

which we solve for $$\mathbf{e_s}$$. The total field $$\mathbf{e} = \mathbf{e_p} + \mathbf{e_s}$$.

The primary field is estimated from a background model (commonly as a 1D model).

Attributes

 sigmaPrimary A background model, use for the calculation of the primary fields.

MT: 3D: Forward

MT: 3D: Forward