Introduction

CVLGrid is 2-D grid generation software developed by Dynamic Solutions International, LLC for use with curvilinear orthogonal models, and in particular for use with EFDC_DSI, EFDC_SGZ, EFDC_EPA, and EFDC_Hydro models. As all EFDC models require 2D curvilinear orthogonal grids this tool has been developed to meet this need for DSI and our clients and customers. This tool has been further optimized for us with the EFDC_DSI/EFDC_Explorer Modeling System.

Grids are a key component when generating models using Navier-Stokes equations with the numerical method. This software uses Laplace equations to generate curvilinear grids that allow for more accurate modeling calculations than a standard rectangular grid. In order to achieve optimal accuracy of a model, the grid should be shaped to the model domain and maintain orthogonality. The average orthogonal deviation for grid computation should be less than 3^o to maintain the accuracy of the numerical model.

This program uses the method of Successive Over-Relaxations (SOR) to solve the Laplace equations. To maximize calculation efficiency and reduce the number of iterations required, an optimum relaxation factor must be determined and used in the SOR equations. CVLGrid automatically calculates and implements this optimum relaxation factor for the current grid.