Improved flow modeling in transient reactor safety analysis computer codes

M. J. Holowach, L. E. Hochreiter, F. B. Cheung

Research output: Contribution to conferencePaperpeer-review


A method of accounting for fluid-to-fluid shear in between calculational cells over a wide range of flow conditions envisioned in reactor safety studies has been developed such that it may be easily implemented into a computer code such as COBRA-TF for more detailed subchannel analysis. At a given nodal height in the calculational model, equivalent hydraulic diameters are determined for each specific calculational cell using either laminar or turbulent velocity profiles. The velocity profile may be determined from a separate CFD (Computational Fluid Dynamics) analysis, experimental data, or existing semi-empirical relationships. The equivalent hydraulic diameter is then applied to the wall drag force calculation so as to determine the appropriate equivalent fluid-to-fluid shear caused by the wall for each cell based on the input velocity profile. This means of assigning the shear to a specific cell is independent of the actual wetted perimeter and flow area for the calculational cell. The use of this equivalent hydraulic diameter for each cell within a calculational subchannel results in a representative velocity profile which can further increase the accuracy and detail of heat transfer and fluid flow modeling within the subchannel when utilizing a thermal hydraulics systems analysis computer code such as COBRA-TF. Utilizing COBRA-TF with the flow modeling enhancement results in increased accuracy for a coarse-mesh model without the significantly greater computational and time requirements of a full-scale 3D (three-dimensional) transient CFD calculation.

Original languageEnglish (US)
Number of pages6
StatePublished - 2002
Event10th International Conference on Nuclear Engineering (ICONE 10) - Arlington, VA, United States
Duration: Apr 14 2002Apr 18 2002


Other10th International Conference on Nuclear Engineering (ICONE 10)
Country/TerritoryUnited States
CityArlington, VA

All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering


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