i am doing simulation on three phase,namely air,water and steel beads.i am getting problem in defining the materials in fluent.i define air and water as fluid phase and steel as solid phase.but when i open the panel for phases it shows only ais and water. plz help in this regard.

With define/phases you can just define the fluid phases. the solid phase is to define in the boundary conditions panel.

If you want to model the beads as granular phase, you have to define the steal as a fluid too. Under define phases, there is a option for granular media. You can find more about it in the fluent-ug chapter 18 (use of multiphase-models) and further on.