Three-dimensional thermal and fluid mixing analysis using the mass-flow-weighted skew-upwind differencing scheme. Final report. [PWR]
The upwind finite difference scheme used in the COMMIX-1A code to approximate the convective transport term was shown to contribute more artificial diffusivity to the computed temperature field than the total physical diffusivity that could be inferred from experimental observations of the thermal mixing processes. With aim to reduce such numerical error, a new finite difference scheme called the mass-flow-weighted skew-upwind approach was developed, incorporated in COMMIX-1A, and evaluated by comparison with known analytical solutions and experimental data. This report describes the follow-on activities pursued to demonstrate the applicability of the new finite difference scheme to simulations of pressurized thermal shock events. These activities include benchmarking the code against the Creare one-fifth-scale test 51 and simulating mixing in the full-scale cold leg and downcomer of a Babcock and Wilcox plant using both the upwind and the mass-flow-weighted skew-upwind finite difference scehmes. The new scheme is shown to considerably reduce the amount of artifical diffusivity contributed to the computed temperature field by the convective term approximation.
- Research Organization:
- Babcock and Wilcox Co., Lynchburg, VA (USA). Utility Power Generation Div.
- OSTI ID:
- 5817944
- Report Number(s):
- EPRI-NP-3870; ON: TI85920539
- Country of Publication:
- United States
- Language:
- English
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