Μ(I) rheology
In granular mechanics, the μ ( I ) {\displaystyle {\boldsymbol {\mu (I)}}} rheology is a rheological model for granular flows, describing the evolution of the macroscopic friction coefficient μ {\displaystyle \mu } as a function of the dimensionless quantity I {\displaystyle I} called the Inertial number. == Details == The complete μ ( I ) {\displaystyle \mu (I)} rheology model proscribes constitutive equations for the evolution of macroscopic friction coefficient μ {\displaystyle \mu } as well as the granular (or particle) volume fraction ϕ {\displaystyle \phi } , as a functions of I {\displaystyle I} .