Estimating Uncertainty in Computations of Two-Dimensional Separated Flows
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
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The present paper investigates sources of uncertainties in two- dimensional flow computations and presents methods for estimating them. Two sample problems are used for illustration. The following categories are explored in detail 1 Uncertainty due to truncation error in numerical schemes 2 Uncertainty due to discretization error 3 Uncertainty due to outflow boundary conditions 4 Uncertainty due to incomplete iterative convergence 5 Uncertainty due to computational grid aspect ratio. The error estimates are based on requirements for internal consistencies in computed results. Therefore, they provide better judgement of the numerical solution integrity than comparisons to experimental data or benchmark solutions whose reliability may sometimes be questionable. Ideally, both approaches should be employed. New results are presented on the optimum grid-cell aspect ratio for computational accuracy and efficiency.
- Numerical Mathematics
- Fluid Mechanics