In the present study, commonly used weakly compressible lattice Boltzmann method and Guo incompressible lattice Boltzmann method have been used to simulate fluid flow in a stirred tank. For this purpose a 3D Parallel code has been developed in the framework of the lattice Boltzmann method. This program has been used for simulation of flow at different geometries such as 2D channel fluid flow and 3D stirred tank fluid flow. It has been shown that in addition to elimination of compressibility error, the Guo incompressible method eliminates mass leakage error from the fluid flow simulations although its implementation is as easy as the weakly compressible Lattice Boltzmann method. By the way, comparison between results of the two methods shows that differences in local flow quantities are negligible in both methods; however, for overall flow quantities, the results of Guo incompressible method are more accurate than those of weakly compressible method. تفاصيل المقالة