PhD Thesis - staffweb - University of Greenwich

PhD Thesis by John Ewer.1.3.2.5 Validate the correctness of the interactive prototypeThe prototype interactive CFD system was validated for computational consistency with theresults from the legacy CFD code, with results from other commercial CFD codes and, whereavailable, with experimental data. The new interactive system had to perform a selected rangeof simulations to an acceptable solution tolerance when compared with existing comparisoncodes, experimental data or analytical solutions. A suitably diverse coverage of validation caseswas devised to exercise all of the coupled numerical modules within the system. Expert CFDpractitioners were asked to check that the prototype CFD system produced acceptablyconsistent results.1.3.2.6 Construct suitable test cases to test for the benefits of interactive controlTest cases were chosen to evaluate the benefits and disadvantages of the interactive nature ofthe prototype system.An investigation of the time benefits or overheads due to the use of user interaction could notbe performed easily in different CFD systems. This was because of differences already inherentfrom the development languages, internal architectures and solution algorithms. Such differencesalready produce large variations in run times between the various CFD systems. This effect isobserved without even considering the influence of the User Interface. Test cases wereconstructed and used to investigate the benefits of user interaction when optimising the solutionstrategy as the run proceeds when compared to a "batch mode" run of the same software. Thesetimings were then compared with the non-optimised simulations to give a reasonable indicationof relative performance. Other, less quantifiable, benefits (e.g. error detection and preventionor stability enhancement) could really only be investigated by allowing real users to experimentwith their own simulations to see if either stability or timing enhancements could be made inpractice, but such investigation was outside of the scope of this study. The qualitative benefits,observed during this research, are discussed as appropriate but no extensive investigation wasconducted into these benefits.Group solver control techniques were also investigated to determine if dynamic or static1-8