Solute Data Object dialog

Item	Description
Enable Basic (checkbox)	If checked, enables single substance water quality simulations.	Note: Basic water quality and MSQ can be simulated at the same time.
Enable MSQ (checkbox)	If checked: enables MSQ water quality simulations shows the MSQ tabs
Test MSQ (button)	This will report any errors in the setup of the MSQ model. Note that when MSQ is applied to a network, there is additional validation.
Save (button)	Saves any changes made to the dialog.

Basic Water Quality tab

This is for specifying single species water quality simulations.

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Parameter

Default

Description

Conservative Substance

Unchecked

Check this box to model a conservative substance: bulk and wall coefficients are assumed to be zero.

Leave this box unchecked to model a non-conservative substance: bulk and wall coefficients defined for pipes are used when calculating decay values.

Initial Concentration for Unset Nodes

0.00 mg/l

The initial concentration of the substance being tested at the start of the simulation.

This value is used for nodes at which the initial concentration has not been set (editable on the Water Quality Profile page of the Node property sheet).

Basic nodes, hydrant nodes and reservoirs	The figure is an initial concentration. This will be washed away over time.
Fixed head, transfer nodes and wells	These nodes are inputs to the system. The initial concentration represents a continuous input concentration over the period of the simulation.

Concentration Limit

0.00 mg/l

Limiting concentration used in the calculation of the bulk and reservoir reaction equations.

Michaelis-Menton Kinetics

Unchecked

Check this box to use the Michaelis-Menton rate equation when calculating reaction rates. The equation produces first-order behaviour at low concentrations and zero-order behaviour at higher concentrations. This setting overrides the Bulk Equation Order (applies a value of -1). This setting does not affect the Reservoir Bulk Equation Order.

Bulk Equation Order

1

Reaction order used in the calculation of bulk flow reaction rate. Use 0 for zero-order reactions, 1 for first-order reactions, 2 for second-order reactions, and so on. Use any negative number for Michaelis-Menton Kinetics. Values between 0 and 1 default to 0.

Wall Equation Order

1

Reaction order used in the calculation of pipe wall reaction rate. Choices are 1 for first-order reactions or 0 for constant rate reactions. Any non-zero value defaults to 1.

Reservoir Bulk Equation Order

1

Reaction order used in the calculation of reaction rate of a substance with material in a reservoir. Calculated independently to the Pipe bulk equation order, but the same limitations apply to the choice of values.

Molecular Diffusivity

1.21x10-9 m2/s

Molecular diffusivity of substance being transported, used in the calculation of pipe wall reaction rate.

MSQ Solutes tab

For defining any number of solutes.

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Item	Description
WQ Solute ID	The solute IDs are used in property sheets and in the results. All IDs must be unique within this grid.
WQ Solute Description	The description of the water quality solute ID.
Solute Type	Specifies whether the solute is present in the bulk liquid or on the pipe walls.
Initial Concentration for Unset Links	Concentrations are defined as follows: Pipes have concentration in the water body and on the wall. Reservoirs and nodes in general have concentration in the water body, and they can provide incoming sources. Initial concentrations can be set for: Reservoirs and nodes types in general, initial values in the bulk of water. Link types; defines initial concentrations for adsorbed solutes. Note: these initial concentrations are for “unset nodes” or “unset links”. They are global default values that can be overridden for individual model objects.
Initial Concentration for Unset Nodes

MSQ Constants tab

Constants are used to make equations clearer to read and are optional.

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Any number of constant IDs can be defined with associated numerical values. The constant IDs are replaced by the numerical values when the engine acts upon the equations.

MSQ Variables tab

Variables are used to make equations clearer to read and are optional.

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Variable IDs are defined, one per line in the text editor. Variables define an expression by combining constants, numerical values, algebraic operators, and reserved keywords.

MSQ Reservoir Equations tab

The way that solutes change through time within reservoirs is defined in this tab.

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One solute is defined per line in this text box. Only dissolved (bulk) solutes are considered in this section.

For each solute, provide an equation that defines change through time. This can be defined in either of two ways:

a rate of change, designated “DDT (A5) = ….”
reversible reactions (that is, equilibria) are designated “A5 = …”. This is designed for rapid reactions.

The equation for each solute is composed of numbers, arithmetic operators, constants, variables, and solute IDs.

MSQ Pipe Equations tab

The way that solutes change through time in pipes is defined in this tab. This deals with changes to adsorbed solutes as well as those dissolved in the bulk of the water.

The construction of equations for Pipes follows the same rules as for reservoirs. The exception is that pipe equations can also include adsorbed solutes.

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Keywords and operators for the MSQ variables and equations tabs

Keywords

DIAM	pipe diameter
SAV	pipe surface area per unit volume
FLOW	pipe flow
VEL	pipe velocity
RE	Reynolds number
VSH	shear velocity
DWF	Darcy-Weisbach friction factor
CWK	Colebrook-White roughness
HWC	Hazen-Williams coefficient

Operators

'('

')'

'**' and '^' are alternative forms of exponent operator

'*'

'/'

'+'

'-'

'='

Right side functions

SIN( )	COS( )	TAN( )	COT( )
ABS( )	SGN( )	SQRT( )	LOG( )	EXP( )
ASIN( )	ACOS( )	ATAN( )	ACOT( )
SINH( )	COSH( )	TANH( )	COTH( )
LOG10( )	STEP( )

Left side function

DDT()

rate of change of solute