Examine Iterative Convergence
● 3 to 4 orders of magnitude
● conservation of mass/energy
X Examine Spatial (Grid) Convergence
● ordered discretization error
X Examine Temporal Convergence
● N/A → Steady State Simulation
Compare CFD Results to Data
● “Average” Pressure Drop
● “Average” Mass Flowrate
Examine Model Uncertainties
● Turbulence Models/Solvers
X Not Performed
Reference: NPARC Alliance CFD Verification and Validation Web Site
Validation – Iterative Convergence
Energy Equation Residual Response
1. Activating heat transfer (q” ~ 1 MW/m2 )
2. Sdr and Tke “noise
85 Million Element Model (3.02.003)
Understand Capabilities – “File Size”
27 GB File Size
– Parallel I/O
– Optimal Topology
– Save Times
– File transfer
– File sharing
• M&S “Large Problems” is Challenging
• parallel mesher needed
• Validation is Challenging
– experimental data availability
• Understand Capabilities and Limitations
– HPC machines
– network infrastructure
– human infrastructure
• Key Success Factor → “SYNERGY”
1. K.D. Hamman and R.A. Berry, “A CFD M&S Process for Fast Reactor Fuel
Assemblies,” Experiments and CFD Code Applications to Nuclear Reactor
Safety (XCFD4NRS 2008), Grenoble, France, accepted, 2008.
2. CD-adapco, “Star-CCM+ (2.08.004) User Guide”, 2007.
3. N. E. Todreas and M. S. Kazimi, “Nuclear Systems I, Thermal Hydraulic
Fundamentals,” Hemisphere Publishing Corporation, 1990.
4. N. E. Todreas and M. S. Kazimi, “Nuclear Systems II, Elements of Thermal
Hydraulic Design,” Taylor and Francis, 2001.
5. Y. I. Chang, P. J. Finck, and C. Grandy, “Advanced Burner Test Reactor
Preconceptual Design Report,” ANL-ABR-1, September 2006.
6. E. H. Novendstern, Turbulent Flow Pressure Drop Model for Fuel Rod
Assemblies Utilizing a Helical Wire-Wrap Spacer System, Nuclear
Engineering Design, Vol. 22, pp. 19-27, 1972.
7. K. Rehme, Pressure Drop Correlations for Fuel Element Spacers, Nuclear
Technology, Vol. 17, pp. 15-23, 1972.
8. R. Gajapathy, et al., CFD investigation of helical wire-wrapped 7-pin fuel
bundle and the challenges in modeling full scale 217 pin bundle, Nuclear
Engineering and Design (2007), doi:10.1016/j.nucengdes.2007.05.003.
9. NPARC Alliance CFD Verification and Validation Web Site
(www.grc.nasa.gov/WWW/wind/valid/validation.html), accessed 11/1/07.