GWaterRun  Java Application download (tar file) What: GWaterRun is a Java Application designed to simulate the activity of a physical small-scale aquifer model as pictured below. These simulators are commercially available from enVision Environmental Education (directly corresponds to current version) or Crystal Scientific LLC (similar product with different boundary conditions - original code was based on this product).  How: The link above will download the application as a tape archive (tar) file, which can be unarchived using most unzip software. Apple OSX system users can start the application by double-clicking on the GWaterRun application icon. Windows users will need to execute the GWaterWinRun.bat file. Aquifer canvas: The main portion of the interface consists of a 25x15 grid of white boxes, marked with a set of black ‘flags’ corresponding to the physical tubes (‘wells’) for the injection of pollutant dye on the physical simulator. Clicking and/or dragging across the grid interface will ‘paint’ corresponding grid boxes with the color highlighted on the palette to the right. Different colors, (including ‘blank’ white), can be selected by clicking on the corresponding palette buttons, which will be highlighted in black, along with the matching colors on the canvas. Each color can be selected to represent a particular soil type in the model profile. Well flags: Clicking the black taps a top the dark vertical lines will change the color of the flag to red, then blue, then green then back to black. The non-black colors represent filling the well with a particular color pollutant dye. Permeability palette: Each paintable grid color matches with a slider bar and a value from 0.00 to 1.00, representing impermeable (0.00) to vacant/completely permeable (1.00). These numbers can be adjusted in increments of 1/100. Buoyancy factor: This slider bar ranges from -.01 to +.01 and represents a tendency of a given pollutant to float (positive values) or sink (negative values). Dissipation factor: This slider bar ranges from 0 to 1, representing the likelihood that a pollutant veers from the flow path, with a value of 0 confining the pollutant directly to the flow path and 1 allowing for motion in any direction, unaffected by the flow. File menu - Load, Save, Save As... : The model geometry (and associated numbers)can be named and saved as a text file with the suffix ‘.dat’ through the appropriate selection. Saved profiles can also be loaded - a file ‘gridA.dat’ is included with the download. Edit menu - Paint: The default paint functionality is to fill a single grid point (1x1). The canvas can be colored more quickly by selecting a larger fill space, which will create a 3x3 or 5x5 square centered on the cursor. Edit menu - Wipe Palette: This selection will fill the entire grid with white ‘blank’ blocks. Edit menu - Regrid: The canvas can be gridded with either a finer or courser grid by selecting one of the submenu choices. The graph profile will be approximately retained. Note processing the finer grids may take some time, and will increase the time necessary for other program calculations. Show menu - Boundary Conditions: When selected (indicated by a check mark), this choice will highlight the nodes on the grid where the hydraulic head is set equal to the height of the entire tank (in blue), where the head is set equal to the actual height of the node (in green), and the boundary lines over which a flow gradient is not allowed (black lines in the allowed direction, perpendicular to the prevented flow). Show menu - Flow Field: When selected (indicated by a check mark), this choice will execute a computation that determines the value of the hydraulic head at every grid point and then plots a vector (red arrow) at each point representing the direction of fluid flow. A computational determination of the water level is represented with a blue line. The colors of the grid are faded with white so that the flow field is visible. This is the most computationally intensive part of the program, and may take some time for the finer grids. Show menu - Wells: When selected, this choice will show or hide the vertical black well ‘flags’. Simulate - Run: Choosing this function simulates motion of a pollutant through the aquifer. Each well flag that is selected with a particular dye color will generate a unit of dye, represented by a colored dot. Each dot moves based on the condition of the flow field and the buoyancy and dissipation factors. The simulation required the same calculation as showing the flow field, so may take some time before starting. Simulate - Stop: This function stops the calculations and simulated dye movement, which can be resumed with the ‘Run’ function. Simulate - Restart: This function clears all dye markers and runs the simulation from the start. Simulate - Time Step: This function presumes the program is not running, and executes a single computation that moves each dye marker once. Why: This applet was created as a pilot example for a groundwater education collaboration between the Shodor Education Foundation, National Science Teachers of America, the Department of Defense Education Action and the Environmental Protection Agency. The main project proceeded with explorations of unsaturated groundwater flow. This example, featuring pollutant transport in the saturated zone, has been used to demonstrate aspects of computational science education as part of the National Computational Science Institute, and has been used in demonstrations at the middle, secondary and undergraduate level. The applet uses a finite element computation to determine the flow field and then uses the velocities in the flow field to calculate the trajectories of the dye markers.http://www.shodor.org/~grl/Jcodes/GWaterRun.tarhttp://www.envisionenviroed.net/shapeimage_2_link_0shapeimage_2_link_1