A simulation of filter cake formation as a random process has been conducted. The random packing occurs after spherical particles are generated at a randomly selected coordinate above the cake. The force balance of the particles considers the driving force of filtration, skeleton forces due to virtually overlying particle layers, and adhesive forces. The factors for determining when a particle stops are defined as follows: a. Adhesion to the contacting particles based on the force balance. b. Finding a steady position if contacting three or more particles of the cake. The calculations deliver local porosities, mean porosities and size distributions of the pores dependent on the filtration parameters. The results confirm observations made in filtration experiments. (C) 2009 Elsevier B.V. All rights reserved.