Due to the importance of the issue of dust on the air and its dangers, this thesis attempts to use the numerical simulation based on Computational Fluid Dynamics (CFD) to examine the concentration distribution of this parameter (coal dust) produced by a working face located in the crosscut of longwall face. Therefore, models of the combination of various auxiliary ventilation systems are proposed and simulated, and the impact of each model has been assessed on: a) the distribution of fresh air flow into the desired geometry and how to ventilate these areas; b) the distribution of released and distributed dust particles within the range c) Distribution of methane gas concentration that is released into the environment with dust particles through the working face. These models are simulated from the combination of auxiliary ventilation systems (Brattice, Duct and Fan) and accurate information on the flow path, air velocity, methane gas concentration and coal dust concentration which are the key parameters in this study is achieved. In these models, changes are made to the important parameters of the duct and the fan system (the diameter and the distance of duct inlet from the working face), the brattice parameters (brattice distance from the tunnel wall and brattice length), and the air velocity, and the impact of each is studied. This information contributes to increase the efficiency of the ventilation system in hazardous areas, including dead-end and polluted areas of gas and coal dust where the risk of explosion is high. The simulation based on computational fluid dynamics includes some basis, and it is possible to be solved by various differential equations and implementing approximations to a linear equation system. Since the thesis describes a two-phase solid-gas environment (methane gas- coal dust) and there is an exhaust fan technology as an auxiliary ventilation, therefore, in addition to solving the flow equations and determining and solving the turbulence models, the corresponding equations to the gas phase with the species model, the solid phase equations with the Discrete Phase Model (DPM) and the equations of the fan are also solved. The simulatio
