As discussed in chapter 1, incompressible ows represent a broad range of uid ows with relatively low speeds, typically for Mach number M < 0.3. Due to the very high computational costs associated with DNS, state-of-the-art DNS is mainly restricted to low Reynolds number ows in simple geometries. ere has been a substantial amount of DNS of incompressible ows in simple geometries due to the relatively low speeds of incompressible ows, and hence relatively lower computational costs compared with high-speed ows when all the scales need to be resolved. One example is DNS of channel ows, which are of great importance to many practical applications and fundamental uid dynamics research. is chapter presents a few applications of DNS to incompressible ows with some sample results of DNS of channel ows. Discussions on the numerical features of the simulations are also presented.