Specifying the Dimensions, Initial Value and Rates of Change for a Reservoir

The primary output For an element with multiple outputs, the output that has the same name as the element. of a Reservoir A stock element that integrates and conserves flows of materials. is its Value. The Display Units The units (e.g., m, g, $/day) in which an output is displayed within GoldSim. determine the dimensions An output attribute for an element that defines the dimensionality (in terms of Length, Time and other fundamental dimensions) of the output. of this output. The primary output of a Reservoir is always a value (it cannot be a condition), but can be specified as a scalar An output consisting of a single value or condition., a vector A one-dimensional array. or a matrix A two-dimensional array.. You can specify the order by pressing the Type... button. By default, the primary output of a new Reservoir element is a scalar, dimensionless value.

The Initial Value input to the Reservoir must have the same attributes (order and dimensions) as the primary output.

Note: The Initial Value must be a number or a link from a static variable (e.g., a constant Data element An input element intended to represent constant inputs in a model. or a Stochastic).

There are two Rate of Change inputs: one representing Additions and one representing Withdrawal Requests. These inputs must have the same order (i.e., scalar, vector, matrix) as defined for the element. Moreover, the dimensions must represent a rate of change of the primary output (e.g., if the primary output has units of mass, the Rate of Change inputs must have units of mass per time).

The Rate of Change inputs must be entered as non-negative values. Negative values for these inputs during a simulation will result in a fatal error.

Note: The specified Rate of Change inputs represent constant rates over the next timestep A discrete interval of time used in dynamic simulations.. Hence, if an Rate of Change was defined as “if(time > 10 day, 2 m3/day, 1 m3/day)”, and you were using a 1 day timestep, the rate would not actually change to 2 m3/day until time = 11 days. That is, since at time = 10 days, the if statement indicates that the rate is equal to 1 m3/day, GoldSim would assume that the rate was equal to 1 m3/day between 10 days and 11 days. If you wanted the rate to change at 10 days, you would write the if statement as “if(time >= 10 day, 2 m3/day, 1 m3/day)”.

Note: If the output of a Reservoir is specified as being an array A collection of variables that share common output attributes and can be manipulated in GoldSim elements or input expressions. (a vector or a matrix), the Initial Value and Rate of Change inputs must, by definition, themselves be arrays. Since you often may wish to enter a zero array (a vector or matrix of zeros) for one or more of these inputs, GoldSim allows you to leave any of these input fields blank, in which case it interprets the field as a zero array.