The majority of the applications of fluid dynamics refer to fluids that during the flow the particles areconserved. It is natural to have in mind such physical applications when examining the 4th ClayMillennium Problem. The assumptions of the standard formulation of the above problem, althoughreflecting the finiteness and conservation of the momentum and energy, as well as the smoothness ofincompressible physical flows, do not reflect the conservation of particles of the fluid as local structure.By formulating the later conservation law and adding it to the hypotheses, it becomes possible to provethe regularity both for the Euler and Navier-Stokes equations. From the physical point of view this maymean that: if a) the particles like neutrons, electrons and protons remain such particle during the flowor if atoms exist in the fluid that if b) the atoms remain atoms of the same atomic number during theflow or if there are molecules in the fluid, if c) the molecules remain molecules of the same chemicaltype during the flow, then the regularity (smoothness of flow at all times) for the 4th Clay Millenniumproblem is provable and holds. The methodology for such a proof is based on proving that if a Blow-upwould exist then at least for a particle range, the total energy would also converge to infinite (seePropositions 5.1, 5.2) which is a contradiction to the hypothesis of finite initial energy of the standardformulation of the 4th Clay Millennium problem.