Model Verification, Calibration, and Validation

As the use of CFD models continues to raise to support the analysis of complex water infrastructure projects, they need to be adequately verified, calibrated, and validated; processes typically termed for simplicity as VV. Verification and validation are the primary means to assess accuracy and reliability in computational simulations. Such processes are key components of the best CFD modeling practices involving, among others, convergence and mesh independency tests, whereas they are antecedent to postprocessing visualization, documentation, and reporting steps. In CFD, the amount of uncertainty involved depends directly on the solution of the Navier-Stokes equations, which are technically parabolic nonlinear, nonhomogeneous, partial differential equations. Once model verification is carried out, the model needs to be calibrated. Calibration ensures that the matching between analytical or experimental values and model results is accurate within established standards via the iterative adjusting of model parameters.