VERIFICATION OF MODELS OF UNSATURATED FLOW AND TRANSPORT IN UNSATURATED ZONE BY EXAMPLE OF CODE GeRa
I. V. Kapyrin, V. V. Suskin, A. V. Rastorguev, K. D. Nikitin
VANT. Ser.: Mat. Mod. Fiz. Proc 2017. Вып.1. С. 60-75.
The main objective of the present work is the verification of a possibility to use the GeRa code to simulate the unsaturated flow and transport processes in unsaturated zone, i.,e. the verification of the corresponding models implemented in the code. Such problems are of most importance for the safety assessment of near-surface disposals of radioactive wastes and the other nuclear- and radiation-dangerous objects. The paper presents the analytical and numerical models implemented in the GeRa code and describing the unsaturated flow and transport processes in unsaturated zone. A set of four verification tests is presented, which are the well-known problems described in literature: the problem of a 1D unsaturated flow into dry soil (Selia test); the Oldenburg and Pruss problem of a capillary barrier; the problem of a 2D saturated-unsaturated flow and transport in heterogeneous unsaturation zone (a training problem for the VS2DT code); and the full-scale experiment on the unsaturated flow and mass transport in a region with drain. For each of the four problems a good qualitative agreement with analytical solutions and experimental data has been achieved and the comparison with results of the well-known codes FEFLOW, HYDRUS-1D, TOUGH2, VS2DT is presented. For the first time, the authors proposed and tested the numerical model of moisture transport using the piecewise-linear replenishment of the height of inflow in cells of computational grid. Keywords: unsaturated flow, transport in unsaturated zone, verification, cross-verification.
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