specularity coefficient shear boundary in Fluent
 

There are two coefficients in johnoson and jackson boundary condition for the simulation of particle velocity at wall: restitution for particle-wall collisions and specularity factor. but only the specularity factor could be found in Fluent, why?

This is because you only defined the particle-wall coefficient of restitution in fluent when the full partial differential equation for the granular temperature (GT) is applied. No boundary conditions are needed for the algebraic GT equations is used. However, the specularity coefficient is needed for the momentum boundary condition so it will always be asked for.

thanks a lot~