A number of important processes depend on the permanence of particle attachment to surfaces by Van der Waal forces in the presence of flowing fluids. These include enzyme fixation, particle filtration, oil production, nuclear reaction excursions, migration of surface contaminants, etc. For the purpose of this study, particles are classified as Brownian or non-Brownian, where Brownian particles are defined as those for which the diameter is les than five microns and on-Brownian are those with diameter greater than five microns. The major focus of this work is on the second category. The particle release process has been studied both theoretically and experimentally, and it is found that for non-Brownian particles the surface and the electrolyte composition of the flowing phase are less significant factors than the hydrodynamic effects. However, Van de Waals forces are found to be important and the distortion of particles by these factors is shown to be crucial. In this investigation, they experimentally determine the factors controlling the release of non-Brownian particles. Also, they discover the initial particle release mechanism (i.e., rolling-vs-sliding).