In this study, the numerical analysis for laminar and turbulent flows around a circular cylinder is carried out from Reynolds number $10^4;to;10^6$, where the dramatic change of drag coefficients exists around Reynolds number $4{ imes}10^5$. The numerical results are compared with those of the experiments and they show reasonable agreements. The good results can be obtained without turbulent model by minimizing mesh size in the body normal direction and increasing mesh numbers in the body tangential direction. The future study for 2-dimensional flat plates with no pressure gradients and 3-dimensional bodies must be made to verify whether the same conclusions can be drawn.