DNS 1-3 Computational Details
Computational Details
Computational approach
Provide an overview of the numerical method/setup used for the computation of the DNS or LES database. This includes a description of the spatial and temporal discretisation, order of accuracy; if applicable implicit iterative strategy and associated convergence criteria. If available, also provide the spectral analysis curves (von Neumann analysis). In case LES is used, provide a brief description of the SubGrid Scale (SGS) model. Avoid unnecessary detail if good references are available.
Spatial and temporal resolution, grids
A mesh resulting in approximately 250 million degrees of freedom (DoF). With a stretched grid, the maximum grid resolution in the duct centre is reported at Δz + = 11.6, Δy + = 13.2 and Δx += 19.5. Correspondingly, the wall resolution (in terms of the first grid point) is reported as z += 0.074, y + = 0.37 in the spanwise and normal directions, respectively, is used. This resolution was deemed sufficient to compute the flow in the diffuser and is based on the previous work of Ohlsson et al. For the temporal resolution a third order explicit Runge Kutta method using a dynamic time stepping with CFL below 0.9 has been used.
Computation of statistical quantities
Describe how the averages and correlations are obtained from the instantaneous results and how
terms in the budget equations are computed, in particular if there are differences to the proposed
approach in Introduction.
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