3 papers
physics.geo-ph2026
Higher--order gradient modeling of velocity dispersion in tight sandstones with implications to agroseismology
Rafael Abreu, Ashay Motghare, Chahana Nagesh +2
Modeling frequency-dependent shear-wave propagation in fluid-saturated porous rocks remains a challenge today because existing poroelastic theories generally rely a large number of…
math.NA2026
From complex-step differentiation to a general reconstruction framework
Rafael Abreu, Chahana Nagesh
The complex-step method is traditionally derived from the Taylor expansion of an analytic function and is widely used as a numerical technique for derivative approximation. We pres…
physics.geo-ph2025
On the Fréchet interaction density of certain wave equations
Rafael Abreu, Chahana Nagesh
We extend the adjoint method to complex-valued PDEs and introduce the \emph{Fréchet interaction density}, as the most fundamental interaction from which Fréchet sensitivity kernels…