Contributed by Alberto Passalacqua, Iowa State University

Foam::dragModels::Beetstra
    Drag model of Beetstra et al. for monodisperse gas-particle flows obtained
    with direct numerical simulations with the Lattice-Boltzmann method and
    accounting for the effect of particle ensembles.

    Reference:
    \verbatim
        Beetstra, R., van der Hoef, M. A., & Kuipers, J. a. M. (2007).
        Drag force of intermediate Reynolds number flow past mono- and
        bidisperse arrays of spheres.
        AIChE Journal, 53(2), 489–501.
    \endverbatim

Foam::dragModels::Tenneti
    Drag model of Tenneti et al. for monodisperse gas-particle flows obtained
    with particle-resolved direct numerical simulations and accounting for the
    effect of particle ensembles.

    Reference:
    \verbatim
        Tenneti, S., Garg, R., & Subramaniam, S. (2011).
        Drag law for monodisperse gas–solid systems using particle-resolved
        direct numerical simulation of flow past fixed assemblies of spheres.
        International Journal of Multiphase Flow, 37(9), 1072–1092.
    \verbatim