CODE-TO-CODE BENCHMARKING OF THE PORFLOW AND GOLDSIM CONTAMINANT TRANSPORT MODELS USING A SIMPLE 1-D DOMAIN - 11191
An investigation was conducted to compare and evaluate contaminant transport results of two model codes, GoldSim and Porflow, using a simple 1-D string of elements in each code. Model domains were constructed to be identical with respect to cell numbers and dimensions, matrix material, flow boundary and saturation conditions. One of the codes, GoldSim, does not simulate advective movement of water; therefore the water flux term was specified as a boundary condition. In the other code, Porflow, a steady-state flow field was computed and contaminant transport was simulated within that flow-field. The comparisons were made solely in terms of the ability of each code to perform contaminant transport. The purpose of the investigation was to establish a basis for, and to validate follow-on work that was conducted in which a 1-D GoldSim model developed by abstracting information from Porflow 2-D and 3-D unsaturated and saturated zone models and then benchmarked to produce equivalent contaminant transport results. A handful of contaminants were selected for the code-to-code comparison simulations, including a non-sorbing tracer and several long- and short-lived radionuclides exhibiting both non-sorbing to strongly-sorbing characteristics with respect to the matrix material, including several requiring the simulation of in-growth of daughter radionuclides. The same diffusion and partitioning coefficients associated with each contaminant and the half-lives associated with each radionuclide were incorporated into each model. A string of 10-elements, having identical spatial dimensions and properties, were constructed within each code. GoldSim's basic contaminant transport elements, Mixing cells, were utilized in this construction. Sand was established as the matrix material and was assigned identical properties (e.g. bulk density, porosity, saturated hydraulic conductivity) in both codes. Boundary conditions applied included an influx of water at the rate of 40 cm/yr at one end of the string and no-flow lateral flow boundaries. A unit quantity of each contaminant was introduced at the influx boundaries and the rate of outflux at the opposite end of the 10-element string was recorded to make the comparisons. Saturated conditions were assumed in this evaluation. Under these carefully controlled conditions the two codes produced essentially identical results, demonstrating that both codes appear to be accurately implementing the contaminant transport mechanisms. The conclusion is that a satisfactory basis was established to justify the exercise in which 1-D GoldSim model was benchmarked against the 2-D unsaturated zone and 3-D saturated zone Porflow models used at the Savannah River Site (SRS).
- Research Organization:
- Savannah River Site (SRS), Aiken, SC (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC09-08SR22470
- OSTI ID:
- 993474
- Report Number(s):
- SRNL-STI-2010-00739; TRN: US1008025
- Resource Relation:
- Conference: WM2011 Conference
- Country of Publication:
- United States
- Language:
- English
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