If iwl2cb 0 then mnw cell by cell flow terms will not

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Unformatted text preview: et a variable value to zero. FOR EACH SIMULATION: 0. Data: [#Text] Text A character variable (up to 199 characters) that is printed when the file is read. The “#” character must be in column 1, and, accordingly, the variable starts in column 2. Any characters can be included in Text. Note 1: Item 0 can be repeated multiple times. Text will be printed to the MODFLOW listing (output) file. 1. Data: MNWMAX IWL2CB MNWPRNT {OPTION} MNWMAX is the maximum number of multi-node wells (MNW) to be simulated. IWL2CB MNWPRNT OPTION is a flag and a unit number: • if IWL2CB > 0, then it is the unit number to which MNW cell-by-cell flow terms will be recorded whenever cell-by-cell budget data are written to a file (as determined by the output control options of MODFLOW). • if IWL2CB = 0, then MNW cell-by-cell flow terms will not be printed or recorded. • if IWL2CB < 0, then well injection or withdrawal rates and water levels in the well and its multiple cells will be printed in the main MODFLOW listing (output) file whenever cell-by-cell budget data are written to a file (as determined by the output control options of MODFLOW). is a flag controlling the level of detail of information about multi-node wells to be written to the main MODFLOW listing (output) file. If MNWPRNT = 0, then only basic well information will be printed in the main MODFLOW output file; increasing the value of MNWPRNT yields more information, up to a maximum level of detail corresponding with MNWPRNT = 2. is an optional list of character values in the style of “AUXILIARY abc” or “AUX abc” where “abc” is the name of an auxiliary parameter to be read for each multi-node well as part 46 Revised Multi-Node Well (MNW2) Package for MODFLOW Ground-Water Flow Model of dataset 4a. Up to five parameters can be specified, each of which must be preceded by “AUXILIARY” or “AUX.” These parameters will not be used by the MNW2 Package, but they will be available for use by other packages. For each Multi-Node well (that is, repeat dataset 2 MNWMAX times): 2a. Data: WELLID NNODES WELLID is the name of the well. This is a unique alphanumeric identification label for each well. The text string is limited to 20 alphanumeric characters. If the name of the well includes spaces, then enclose the name in quotes. NNODES is the number of cells (nodes) associated with this well. NNODES normally is > 0, but for the case of a vertical borehole, setting NNODES < 0 will allow the user to specify the elevations of the tops and bottoms of well screens or open intervals (rather than grid layer numbers), and the absolute value of NNODES equals the number of open intervals (or well screens) to be specified in dataset 2d. If this option is used, then the model will compute the layers in which the open intervals occur, the lengths of the open intervals, and the relative vertical position of the open interval within a model layer (for example, see figure 14 and related discussion). Note 2: If NNODES < 0 and elevations indicate multiple well screens or open intervals within a single model layer, then the model will assign a single equivalent composite well screen (see additional discussion in text). 2b. Data: LOSSTYPE PUMPLOC Qlimit PPFLAG PUMPCAP LOSSTYPE is a character flag to determine the user-specified model for well loss (equation 2). Available options (that is, place one of the following approved words in this field) are: NONE there are no well corrections and the head in the well is assumed to equal the head in the cell. This option (hWELL = hn) is only valid for a single-node well (NNODES = 1). (This is equivalent to using the original WEL Package of MODFLOW, but specifying the single-node well within the MNW2 Package enables the use of constraints.) THIEM this option allows for only the cell-to-well correction at the well based on the Thiem (1906) equation; head in the well is determined from equation 2 as (hWELL = hn + AQn), and the model computes A on the basis of the user-specified well radius (Rw) and previously defined values of cell transmissivity and grid spacing. Coefficients B and C in equation 2 are automatically set = 0.0. User must define Rw in dataset 2c or 2d. SKIN this option allows for formation damage or skin corrections at the well: hWELL = hn + AQn + BQn (from equation 2), where A is determined by the model from the value of Rw, and B is determined by the model from Rskin and Kskin. User must define Rw, Rskin, and Kskin in dataset 2c or 2d. GENERAL head loss is defined with coefficients A, B, and C and power exponent P (hWELL = hn + AQn + BQn + CQnP). A is determined by the model from the value of Rw. User must define Rw, B, C, and P in dataset 2c or 2d. A value of P = 2.0 is suggested if no other data are available (the model allows 1.0 ≤ P ≤ 3.5). Entering a value of C = 0 will result in a “linear” model in which the value of B is entered directly (rather than entering properties of the skin, as with the SKIN option). SPECIFYcwc the user specifies an effective conductance value (equivalent to the combi...
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This document was uploaded on 01/20/2014.

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