The prediction of aerodynamic properties of thick airfoils is a tricky business for the blade manufactures. Computational fluid dynamics (CFD) offers a number of significant advantages to investigate the flow properties around airfoils, however, most turbulence models are working properly except having some problems in case of turbulent separation. The spectral/hp elements method offers fast convergence due to the better resolution in a short time. Therefore, we perform direct numerical simulation (DNS) at the Reynolds number (Re) = 3900 , polynomial orders (P)=9 and an angle of attack of = 120 round an airfoil (Fx77-W500) using spectral/hp elements method to solve the unsteady, viscous and two dimensional (2D) incompressible Navier- Stocks equations. A frequent fluctuation of the lift and drag forces has been found over the entire time. The contour plots of pressure and velocity magnitude around the airfoil are investigated for certain cases, which show more vortices at the upper portion of the airfoil and around the trailing edge The presented results show that some interesting and peculiar behaviors due to unsymmetrical airfoil shape, which remind more of a bluff body, that the lift forces show negative value very frequently.