Velocity field calculation for nonorthogonal numerical grids
Computational grids containing cell faces that do not align with an orthogonal (e.g. Cartesian, cylindrical) coordinate system are routinely encountered in porousmedium numerical simulations. Such grids are referred to in this study as nonorthogonal grids because some cell faces are not orthogonal to a coordinate system plane (e.g. xy, yz or xz plane in Cartesian coordinates). Nonorthogonal grids are routinely encountered at the Savannah River Site in porousmedium flow simulations for Performance Assessments and groundwater flow modeling. Examples include grid lines that conform to the sloping roof of a waste tank or disposal unit in a 2D Performance Assessment simulation, and grid surfaces that conform to undulating stratigraphic surfaces in a 3D groundwater flow model. Particle tracking is routinely performed after a porousmedium numerical flow simulation to better understand the dynamics of the flow field and/or as an approximate indication of the trajectory and timing of advective solute transport. Particle tracks are computed by integrating the velocity field from cell to cell starting from designated seed (starting) positions. An accurate velocity field is required to attain accurate particle tracks. However, many numerical simulation codes report only the volumetric flowrate (e.g. PORFLOW) and/or flux (flowrate divided by area) crossing cell faces.more »
 Authors:

^{[1]}
 Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)
 Publication Date:
 OSTI Identifier:
 1172684
 Report Number(s):
 SRNLSTI201500115
 DOE Contract Number:
 AC0908SR22470
 Resource Type:
 Technical Report
 Research Org:
 Savannah River Site (SRS), Aiken, SC (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 97 MATHEMATICS AND COMPUTING
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