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This keyword data block is used to run reaction simulations for a specified set of cells. For a specified cell number, n, all reactants numbered n are reacted together and the resulting reactant compositions are saved to the same cell number. If multiple steps have been defined in KINETICS n, REACTION n, REACTION_PRESSURE n, or REACTION_TEMPERATURE n data blocks, multiple calculations will be done for each cell. It is possible to specify the starting time and the time step for cells that have kinetic reactants; these time values defined in RUN_CELLS supersede the definitions in the KINETICS data block.
unit --Optional time unit may be second , minute , hour , day , year , or an abbreviation of one of these units. The time is converted to seconds after reading the data block; all internal calculations, Basic functions, and output times are in seconds. Default is second.
unit --Optional time unit may be second , minute , hour , day , year , or an abbreviation of one of these units. The time_step is converted to seconds after reading the data block; all internal calculations, Basic functions, and output times are in seconds. Default is second.
The RUN_CELLS data block is a streamlined method for running a simulation that uses all reactants that have been defined with the same identification number (cell number). The calculation for a cell defined in the -cells data block is equivalent to a series of USE and SAVE data blocks for all of the reactants with a specified cell number. If both a solution and a mix definition exist for a cell number, the mix definition is used in preference to the solution. If multiple steps have been defined in KINETICS, REACTION, REACTION_PRESSURE, or REACTION_TEMPERATURE data blocks, then multiple calculations will be done for that cell.
It is possible to specify an initial time for a kinetic integration by using the -start_time identifier and to override the time step from the KINETICS data block by using the -time_step identifier. If -time_step is not defined or a KINETICS data block is not defined for the cell, then the calculations occur exactly as they would by a series of USE and SAVE data blocks. If -time_step is defined, then the kinetic reaction will be integrated over an interval of time_step. If nmax is the maximum number of steps defined for the cell with KINETICS, REACTION, REACTION_PRESSURE, or REACTION_TEMPERATURE data blocks, then the kinetic reaction will be divided into nmax equal increments; the results are equivalent to defining “ -step time_step in nmax steps” in the KINETICS data block. The time_step will be used for all subsequent RUN_CELLS calculations or until it is changed with another -time_step definition in a RUN_CELLS data block.
The RUN_CELLS data block simplifies the definition of repetitive reactions in batch calculations. It also is intended to be used when an IPhreeqc module implements geochemical reactions in a reactive-transport model. For example, if a transport model has a set of cells numbered 1 through n , and the chemical reactants for those cells are saved as identification numbers 1 through n in an IPhreeqc module, then a simple sequential calculation can be implemented. The transport code is used to transport elemental concentrations conservatively, and the concentrations for solutions in the IPhreeqc module are updated with a series of SOLUTION_MODIFY data blocks. Geochemical reactions are calculated by the data block: RUN_CELLS ; -cells 1- n . The new compositions of solutions and reactants are automatically stored in the IPhreeqc module and new solution concentrations are retrieved by extracting data defined by SELECTED_OUTPUT or by the output from a DUMP data block. The new solution concentrations then are used to begin a new conservative transport step.
The keyword RUN_CELLS is used in example problem 20.
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