  In this paper, we present the derivation of a multicontinuum model for the
coupled flow and transport equations by applying multicontinuum homogenization.
We perform the multicontinuum expansion for both flow and transport solutions
and formulate novel coupled constraint cell problems to capture the multiscale
property, where oversampled regions are utilized to avoid boundary effects.
Assuming the smoothness of macroscopic variables, we obtain a multicontinuum
system composed of macroscopic elliptic equations and
convection-diffusion-reaction equations with homogenized effective properties.
Finally, we present numerical results for various coefficient fields and
boundary conditions to validate our proposed algorithm.
