The ADH Model (ADH) is a software package that can describe both saturated and unsaturated groundwater, overland flow, 3D Navier-Stokes, and 3D Shallow Water problems in addition to 2D shallow water equations. A key capability is that ADH can refine and coarsen its mesh automatically.
NSM is a water quality library designed for seamless integration into a variety of hydrodynamic computer codes, and is intended to provide a fast and reliable first look indicator of primary water quality indicators such as dissolved oxygen (DO), carbonaceous biochemical oxygen demand (CBOD), nitrogen (N) etc.
Water quality simulation software codes in the past have overwhelmingly relied on static mesh methods. The difficulty with this method is that the fine mesh resolution, needed to properly define hydrodynamics and water quality, is required throughout the domain. This resolution requires more effort in generating the finite element mesh and significantly increases the computational time.
Integration of NSM as a sub-module with ADH provides users with the ability to take advantage of the mesh/grid adaption abilities of ADH. ADH relies on a calculated residual to determine the degree of grid adaption required for proper hydrodynamic convergence. In addition a 4th order Runge-Kutta time step splitting scheme is implemented to provide for greater accuracy in calculation of water quality parameters.
Figure 1 shows a static pool utilized to simulate the mutual interaction (Figure 2) of dissolved oxygen (DO) and carbonaceous BOD (CBOD). Both DO and CBOD were initialized at a concentration of 5mg/l and the test for run through 1400000 seconds. Notice from the figure that DO as well as CBOD are asymptotically approaching the horizontal axis near the end of simulation, this behavior is expected and the concentrations of DO and CBOD were verified through the use of the standard reaeration equations.
Figure 3 shows the results of a wetting and drying (WD) test conducted to establish the efficacy of the WD equations placed in the second stage of the operator split scheme. The test consisted of a sloshing pool of water with a uniform concentration of dissolved oxygen (DO) at 5.0 mg/l (Figure 4).
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