MOCDENSE

MOCDENSE is a modified version of the ground-water flow and solute-transport model of Konikow and Bredehoeft, which was designed to simulate the transport and dispersion of a single solute that does not affect the fluid density. This modified version simulates the flow in a cross-sectional plane rather than in an areal plane. Because the problem of interest involves variable density, the modified model solves for fluid pressure rather than hydraulic head in the flow equation; the solution to the flow equation is still obtained using a finite-difference method. Solute transport is simulated with the method of characteristics as in the original model. Density is considered to be a function of the concentration of one of the constituents. Use of this model depends on assumptions that:

• Flow is two-dimensional, with one of the principal axes being parallel to gravity,
• Constituents are conservative (nonreactive), and
• Density and viscosity are a function of concentration and not of other factors such as pressure and temperature.

These assumptions are often valid approximations where an aquifer system contains both freshwater and saltwater. This model is applicable in such situations where, ln addition to that of the density-controlling species, the movement and concentration of another chemical species, such as a dissolved pollutant, needs to be predicted. MOCDENSE is also applicable to a two-constituent system with no density-dependence, given that the other assumptions are valid, and to a single-constituent system with variable density.

The maximum dimensions of the flow and transport grids have been increased to 150x150. The limit on the number of particles has been increased from 3,200 to 80,000. The number of observation points which may be specified has been increased from 5 to 25. Observation point data (Density controlling and trace concentrations) may now be saved in a file for plotting with MOCDTIME (not included).

MOCDENSE utilizes extended memory.

This package contains two versions of MOCDENSE: MOCDSIP and MOCDD4. These two versions of MOCDENSE are identical except for the matrix solver. MOCDSIP uses a Strongly Implicit Procedure (SIP) to numerically solve the flow equations while MOCDD4 uses a direct solver with D4 ordering. Also included in the package are the following programs: MOCDINP, MOCDOUT, MOCREC and TECVIEW.

TECVIEW is a program which uses Virtual Memory and page swapping to view and print portions of very large ASCII files. An amount of disk space slightly larger than the size of the file being viewed must be available.

MOCDINP is the input processor for the MOCDENSE model. MOCDINP. MOCDINP is used to Create or Modify the Data File required by MOCDENSE (MOCDD4 or MOCDSIP).

The USGS MOCDENSE report and associated MOCDENSE Computer Update Notes describe all inputs. MOCDINP provides a convenient means of producing the Input Data Files required by MOCDENSE. See below for a description of changes to the structure of the Input Data Files required by MOCDENSE.

The number of nodes in the X and Z directions, NX and NZ, are restricted to 150 and 150, respectively. These values of 100 and 100 for the maximum number of nodes compare to 24 and 20 in the original MOCDENSE source code.

Two new flags, NHYDRO and NOUTPR, have been added to Card 2 of the MOCDENSE data files by TECSOFT. If NHYDRO is non-zero and NUMOBS is non-zero, the Density Controlling and Trace Concentrations for all defined observation points will be saved in an ASCII file. The TECSOFT program, MOCDTIME, may then be used to obtain plots of data automatically. NOUTPR is a flag used to reduce the size of the hardcopy output file. The flag may have the following values:

0: Normal hardcopy output file

1: Eliminates printing of observation point data from the hardcopy output file

2: Eliminates printing of particle tracking data from the hardcopy output file

3: Eliminates both

MOCDOUT is the Output Processor for the MOCDENSE model. MOCDOUT takes, as input, the concentration/velocity vector unformatted file from MOCDENSE (MOCDSIP or MOCDD4) and permits the user to save selected sets of data in an ASCII file. The ASCII file may be later processed by MOCDGRAF to produce graphics.

The hardcopy output file from a MOCDENSE (MOCDSIP or MOCDD4) run contains FORTRAN Carriage Control characters. The FORTRAN Carriage Control characters are ignored by most dot matrix printers. The hardcopy output, therefore, may be difficult to read. The MOCREC (Remove or Execute Control Characters) program removes the FORTRAN Carriage Control characters and substitutes ASCII control codes.

MOCDGRAF (not included) can automatically process any or all concentration (trace and density controlling solutes) or velocity-vector grids contained in the file produced by MOCDOUT and stack the contour/velocity vector plots in a metacode graphics file for subsequent processing with TRANSLATE. The graphics file produced by MOCDGRAF could contain up to 500 plots.

Help is available for most functions within the shell by pressing the <F1> function key while highlighting that function. Exit help by pressing the <ESC> key.

The following sequence applies to a MOCDENSE simulation:

1. Create the MOCDENSE Data File.

2. Run MOCDENSE. Create or Modify a Batch File. Select a Batch File. Choose MOCDSIP or MOCDD4. For most problems MOCDD4 should be used. However, for steady-state cases when grid nodes have zero transmissivity and for cases in which the transmissivity is highly anisotropic, MOCDSIP should be used. The output files are: a Hardcopy Output File and an Unformatted File (if NPNCHV in the data file is non-zero). During Batch File Creation or Modification, if NPNCHV is non-zero, the program prompts for the files (Data File, Hardcopy Output and Unformatted) and the types of data (concentration, velocity vector) which will be saved in the Unformatted File. Any or all may be saved.

3. Process the hardcopy output file with MOCREC, if desired, to remove carriage control characters and replace with appropriate ASCII control characters.

4. Run MOCDOUT if desired. MOCDOUT takes as input the unformatted file from MOCDSIP (or MOCDD4) and outputs an ASCII file. Unformatted data may have been saved for all simulation time steps (NPNCHV=1). Rather than process all of this data with MOCDGRAF, when only a subset is required, MOCDOUT gives the user an opportunity to thin out the data while converting to ASCII.

5. Run MOCDGRAF to contour data and draw velocity vectors. MOCDGRAF is used to contour concentrations (both the trace and density-controlling solutes) and to generate velocity vectors which may be superimposed on the contours. MOCDGRAF reads and processes the ASCII file from MOCDOUT.

6. Run MOCDTIME to plot time vs. Density Controlling concentration or Trace Concentration at specified observation points. MOCDTIME reads an ASCII file produced by MOCDENSE.

MOCDGRAF and MOCDTIME are separate programs specifically developed for use with MOCDENSE. These programs are not included with the MOCDENSE package.

MOCDGRAF utilizes the Extended Memory version. TRANSLATE (included) is used to produce high quality graphics on a variety of devices.

Context sensitive help is available for most functions within the shell by pressing the <F1> function key while highlighting that function. Exit Help by pressing the <ESC> key.

The data associated with the creation of concentration contours and, optionally, the superposition of velocity vectors is entered through a series menus. The program scans the input Data File and sequentially displays the appropriate set of menus for each set of data. Page Up/Down is used to select the various menus.

• Pen Number Selections - Various colors may be selected for the contour plots. Pen selections (colors) apply to all MOCDENSE data sets which are contoured. Separate pen selections may be made for the border, title & labels, contour lines and velocity vectors.
• Graphics Options - The ordinal number of the current data set is displayed and the presence of head, concentration and velocity vector data are indicated. Also displayed are the time step, pumping period, and total elapsed time. The times are displayed in years. The user may select this set of data for contouring. If concentration data is not to be contoured, the program skips to read the next set. If the concentration data is selected for contouring and if velocity vector data is present, the user is prompted to specify whether velocity vectors will be superimposed on the contours.
• Aspect Ratio - The aspect ratio is defined as: the length of the Y-Axis/the length of the X-Axis. The program scans the current set of data, computes the aspect ratio and displays the computed value. The user is prompted to enter the aspect ratio and, thus, may override the computed value.
• Contour Selection Types - Contour levels may be selected in one of three ways: (1) Computer Selects Contour Levels (Default) - The data set is scanned and a set of pleasing, evenly spaced levels is chosen. (2) User Selects Maximum, Minimum and Increment. (3) User Selects Specific Contour Levels.
• Contour Increment and Bounds - Applicable only if the user selects the minimum and maximum contour levels and increment. The program scans the data set and computes the minimum and maximum values of the data to be contoured and computes an interval based on ten contour levels. The data is then displayed. The user may override these computed values with his own selections.
• Selected Contour Levels - Applicable only if the user selects specific contour levels. The program scans the data and computes the minimum and maximum values of the data to be contoured. The data is displayed. The user specifies the number of contour levels which will be selected. The maximum allowable number is 50.
• Selected Contour Levels - This menu is displayed only if the user selects specific contour levels. The desired contour levels are entered through this menu.
• Title/Label Options - Title, X-Axis and Y-Axis labels for heads and/or concentration data may be entered through this menu. Each may consist of a string of up to 40 alphanumeric characters.

MOCDTIME utilizes extended memory. TRANSLATE is used to produce high quality graphics on a variety of devices.

The data associated with the creation of time-concentration plots is entered through a series of menus. The program scans the input Data File and sequentially displays the appropriate set of menus for each set of data.

• Observation Point Data - The number of data sets (number of observation points) which exist in the ASCII data file is displayed. Time plots may be generated for either density controlling concentration or trace concentration data. This choice applies to all data sets in the ASCII file.
• Graph Types - Enter the Graph Type used for time plots. This Graph Type will be used for each set of data processed by MOCDTIME: Linear, Semi-Log, and Vertical Profiles.
• Pen Number Selections - Various colors may be selected for the plots. These pen selections (colors) apply to all data sets plotted using MOCDTIME. Separate pen selections may be made for the border, title & labels, background grid and symbols.
• Number of Curves, Background - If the selected Graph Type is linear or semi-log, the number of curves per plot and the number of plots per page are selected and the choice of whether to draw background grids on the plots is made. The maximum number of curves per plot is five. From one to 4 plots may be drawn per page. If the selected Graph Type is vertical profile, the number of profiles per group, the number of groups per page and the choice of whether to draw background grids on the plots is made. The minimum number of profiles per group is 6. The maximum number of profiles per group is 12. The minimum number of groups per page is one. The maximum number of groups per page is three.
• Pen Number Selections - Curves - If vertical profile plots are to be generated, a single pen (color) may be selected for all curves. Otherwise, pen colors may be selected for up to 5 curves per plot.
• Symbol Selection - ('Y' or 'N'). Applicable for linear and semi-log plots only. Symbols are not drawn on vertical profile plots.
• Symbol Selections - Applicable only for linear and semi-log plots. Separate symbols may be selected for up to five curves per plot. Symbols may be selected from a list of 10 possibilities shown below. Symbol size (Small, Medium or Large) may be selected. In addition, every Nth point may be represented by a symbol.
• Curve Selection - Applicable only for linear and semi-log plots. Curves may be drawn on the plots or may be omitted. If symbols are to be drawn, curves will always be drawn by default. The curves may consist of linear line segments ('L') between data points or splines through the points ('S').
• Vertical Profile Label - Applicable only for vertical profile plots. If 'Y' is selected, a label will be drawn on the time axis. If 'N' is selected, the label will be omitted.
• Title/Label Options - Applicable only for vertical profile plots. A label for the time axis may be entered through this menu. The label may consist of a string of up to 40 alphanumeric characters.
• Default Title/Labels - Applicable only for linear and semi-log plots. If 'Y' is selected, the title and labels entered through Menu 12 will be placed on all plots.
• Default Title/Labels - Applicable only for linear and semi-log plots. A Title, X-axis label and Y-axis labels are entered. These will be drawn on every plot. Each may consist of a string of up to 40 alphanumeric characters.
• Specific Title/Labels - Applicable only for linear and semi-log plots. A Title, X-axis label and Y-axis labels are entered for each plot to be generated. Each may consist of a string of up to 40 alphanumeric characters.