Since the permittivity of any material is usually complex function of temperature, frequency, density, etc. I was wondering if it is possible to use a dynamic permittivity which changes as a function of time using the fdtd method. This would also enable to simulate moving objects. Any hints, keywords, etc.?
FDTD can be applied for modeling of objects with time-varying coefficients. Depending on the type of variation, different techniques can be applied. Commonly, in computational EM the following situations are usually considered:
- linear dispersion: dielectric permittivity ($\epsilon$) and magnetic permeability ($\mu$) of the material vary with frequency $\omega$: $\epsilon(\omega)$, $\mu(\omega)$
- nonlinearity dispersion: $\epsilon(\omega,E,H)$, $\mu(\omega,E,H)$, dependence on the field intensity
In addition, your question implies some multiphysics component (temperature), which, depending on the model can be considered as a simple contribution to material properties nonlinearity, as well as a whole additional physics to solve.
My go-to reference for FTDT in computational EM is
- Taflove, "Computational Electromagnetics", Artech House, 2005.
Chapter 9 "Dispersive and Nonlinear Materials" is talking about the relevant techniques that should be of interest to you.