Author(s): Nils Reidar B. Olsen
Linked Author(s): Nils Reidar B. Olsen
Keywords: No Keywords
Abstract: Today there are several computer programs that can calculate changes in river bed elevations by solving the water flow and sediment transport equations. The current paper focuses on two topics: How can a user of the programs assess the accuracy of the program, and how should the programs be designed to help this user in this task. Common uncertainties in computational fluid dynamics (CFD) results include numerical errors, modeling errors, program bugs and inaccuracies in input parameters and boundary conditions. The errors can be assessed using detailed results from the CFD program together with its documentation. Each uncertainty can be assessed by evaluating the variables against each other, parameter sensitivity tests and testing for simplified cases. The task is made easier if the program is as transparent as possible. This means that the user can see the values of all the relevant variables and intermediate results for the whole computational domain. Together with a comprehensive documentation of the computer program that includes all the formulas used, the user can be able to find the causes of suspicious results, including an assessment of possible bugs. An important tool in the testing of a CFD program is using simplified cases, usually channels with uniform one-dimensional flow where the user can compare the results with well-known one-dimensional formulas.
Year: 2010