[REACTIONS]

**Purpose:**

Defines parameters related to chemical reactions occurring in the network.

**Formats:**

** ORDER BULK / WALL / TANK ** *value*

** GLOBAL BULK / WALL ** *value*

** BULK / WALL ** *pipeID* *value*

** TANK ** *tankID* *value*

** LIMITING POTENTIAL ** *value*

** ROUGHNESS CORRELATION ** *value*

**Definitions:**

**ORDER** is used to set the order of reactions occurring in the bulk fluid, at the pipe wall, or in tanks, respectively. Values for wall reactions must be either 0 or 1. If not supplied the default reaction order is 1.0.

**GLOBAL** is used to set a global value for all bulk reaction coefficients (pipes and tanks) or for all pipe wall coefficients. The default value is zero.

**BULK, WALL,** and **TANK** are used to override the global reaction coefficients for specific pipes and tanks.

**LIMITING POTENTIAL** specifies that reaction rates are proportional to the difference between the current concentration and some limiting potential value.

**ROUGHNESS CORRELATION** will make all default pipe wall reaction coefficients be related to pipe roughness in the following manner:

Head Loss Equation | Roughness Correlation |
---|---|

Hazen-Williams | F / C |

Darcy-Weisbach | F / log(e/D) |

Chezy-Manning | F * n |

where **F** = roughness correlation, **C** = Hazen-Williams C-factor, **e** = Darcy-Weisbach roughness, **D** = pipe diameter, and **n** = Chezy-Manning roughness coefficient. The default value computed this way can be overridden for any pipe by using the **WALL** format to supply a specific value for the pipe.

**Remarks:**

- Remember to use positive numbers for growth reaction coefficients and negative numbers for decay coefficients.
- The time units for all reaction coefficients are 1/days.
- All entries in this section are optional. Items offset by slashes (/) indicate allowable choices.

**Example:**

[REACTIONS]

ORDER WALL 0 ;Wall reactions are zero-order

GLOBAL BULK -0.5 ;Global bulk decay coeff.

GLOBAL WALL -1.0 ;Global wall decay coeff.

WALL P220 -0.5 ;Pipe-specific wall coeffs.

WALL P244 -0.7