We develope an optimised Direct Numerical Simulation (DNS) solver for laminar, transition, and turbulent flow. It utilises the Crank Nicholson scheme for time advancement, and it is spatially accurate up to fourth-order on uniform grids. The solver’s salient features are multi-dimensional parallelisation and modular-based code, which is written in object-oriented C++ language. The DNS solver is developed in the MPI parallel platform using a cubic decomposition technique. The open-source library used for optimisation is MPI, blitz++, YAML, and HDF5 library. The parallel performance analysis of the optimised DNS solver on the multiprocessor computing system (supercomputer) shows 80 (Formula presented.) efficiency. The solver is verified and benchmarked for wall-bounded flows by simulation of laminar, transition, and turbulent flow in a square duct.