Spherical particles 1 mm in diameter are to be fluidized with water at twice the minimum velocity. The particles have an internal porosity of 40 percent, an average pore diameter of 10 μm, and a particle density of 1.5 g/cm³. Prove that the flow through the internal pores is very small compared to the flow between the particles, and that the internal porosity can be neglected in predicting the fluidization behavior.