Simplifying 3D Geometry

SANJIB KUMAR DAS SHARMA

I am trying to model a 3D cylindrical fluidized bed. However, due to the dimensions of the bed, 1.5 m x 0.152 m , and the small grid cells to be used (0.008 m), the number of cells is becoming very large, more than 1 lakh. My computer is an old IBM Intellistation, so that the simulations are running very slow. How to make the simulations run faster without compromising the physics...i.e. maintaining the 3D features (no axi-symmetric case). Please suggest .