Many geophysical fluids, such as dry snow avalanches, can be effectively represented as granular flows. The dynamics of granular flows exhibit distinct characteristics when compared to more classical flows. In this presentation, we will explore the modeling of certain aspects of the complex behavior exhibited by granular flows. Initially, we will introduce a variational approach that facilitates the derivation of constitutive laws. Subsequently, we will employ this approach to develop an Euler-Korteweg type model adapted to granular flows. Finally, we will establish the mathematical well-posedness of the derived model.