Numerical simulations have been undertaken for the benchmark problem in a Square cavity by using computational fluid dynamics software. This work aims at discussing the fundamental numerical and computational fluid dynamic aspects which can lead to the definition of the following meshing methods and turbulence models. The meshes used for the simulation are hexahedral, hexahedral cell with near wall refinement, tetrahedral grid, polyhedral, tetrahedral with near wall refinement and polyhedral mesh with prism layer cells based the near wall thickness of Y+ less than one. The turbulence models used for the simulation work are AKN K-Epsilon Low-Re, Realizable K-Epsilon, Realizable K-Epsilon Two-Layer, standard K-Epsilon, standard K-Epsilon Low-Re, Standard K-Epsilon Two-Layer, V2F K-Epsilon, SST(Menter) K-Omega, and Standard(Wilcox) K-Omega. From these meshes and turbulence models, we will conclude the suitable mesh and turbulence for the recirculation flow by the grid independent test. These analytical values of results are compared with reference data which gives an optimization of experimental work. Unsteady simulation was ran for all the Grid Independent mesh with the SST k omega model with the time step of 0.01 sec for 40 seconds. The flow nature is studied with and without the temperature for Reynolds number, 1000 and 10000.