This work provides a renewed space-time muitiphase model known as “insviscid model”, according to terminology of the multiphase flows theory, where the gas-solid modeling presents some special characteristics such as: unsteady and 3D flow for two fluid on an Eulerian-Eulerian appoach; dissipation of turbulent kinetic energy only on the gas as real fluid; and with assumption of solid phase behaves like some kind of hypothetical fluid without shear stress from molecular causes. By using Computational Fluid Dynamics Techniques (CFD), it was carried out the development of the model with studies of Verification and Validation in Computational Fluid Dynamics (V&V in CFD), in order to predict the main fluid dynamic features of down flow reactors of petroleum industry. Despite the simplified modeling, the renewed gas-solid model has shown a good representation of the main phenomenological characteristics of the turbulent gas-solid flow. Numerically, the model does not present difficulties for convergence with traditional finite volume methods with collocated grids and body fitted arrangement of the control volumes. The model considers, as initial condition for space-time integration, the flow of the single phase (gas) to guarantee stability and to achieve the steady state condition. Experimental data obtained in the literature, Cheng et al. [1], were used for model validation, and three others cases for verification of the fluid dynamics effects from different gas-solid inlet condition. By comparison between the model predictions with experimental data, it is possible to conclude there is a good agreement. CFD techniques proved to be also a powerful tool to predict the fluid dynamic of inlet changing of the down flow reactors, and it can be used with success in chemical process optimization.