Packed beds have been in use for a variety of applications for more than 100 years. Today, they have grown in importance with the emergence of new technologies like the need to generate better ways to store thermal energy in support of renewable sources such as wind, sun and other green energy types. The use of rigid particles has been, arguably, the most versatile packing materials across a broad spectrum of applications. However, to be thorough, one must consider all three categories of particle porosity which make up this broad field. These categories are, (1) nonporous particles (εp = 0), (2) partially porous particles (0 < εp <1) and (3) fully porous particles (εp = 1). Foremost amongst all applications, perhaps, has been the field of HPLC (High Pressure Liquid Chromatography) which, for the most part, utilizes category 2, i.e., partially porous particles, which morphed out of the original field of Gas chromatography. The use of smaller and smaller particle diameters to achieve ever increasing separation efficiencies, however, has generated the need for a comprehensive assessment of the hydrodynamics of packed beds. As particle diameter decreases, the operating pressure drops increase, necessitating higher packing pressures which can result in particle compression when the particles are not sufficiently rigid. In the case of partially porous particles, increased packing pressures can also lead to a reduction in internal particle pore volume. This new assessment requirement dictates the need to develop a unified framework which can seamlessly describe the fluid dynamics of packed beds containing all three categories of particle porosity. In this paper, the goal is to present such a unified methodology with particular emphasis on establishing the fit between the general model and published works, which includes all categories of particle porosity especially those involving the relatively recent development in HPLC columns known as UHPLC (Ultra High-Pressure Liquid Chromatography).