About 1D simulations

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In InfoWorks ICM, the behavior of a network under particular conditions is modelled by running simulations.

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These simulations test the performance of the network over time and are used to identify limits in the system,

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such as nodes that are liable to flood under given conditions.

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The details of particular simulations are set up in the database as runs.

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When a run is set up, one or more time-varying inputs, such as rainfall events, flow surveys, or time-series database objects,

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can be specified for use in calculations.

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A basic 1D hydraulic simulation is easy to set up with the help of the Run View.

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The Run View allows you to create new simulations or edit existing simulations.

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You can add a title and select the relevant InfoWorks network and events or time-series data to be run with the simulation.

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For time-related simulation settings, you can enter relative or absolute times.

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For example, the default time of zero values uses relative time

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which means that the design factors are used for trade and wastewater inflows.

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The simulation parameters govern how the engine performs the model calculations in the hydraulic simulation.

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Default values have been chosen for optimum accuracy and performance for sewer network simulations,

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and therefore do not normally need to be amended.

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However, the parameters can be adjusted if necessary.

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For the majority of typical models, the only time-related adjustment you are likely to make is to the simulation timestep.

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This is the maximum timestep at which the hydraulic calculations will be carried out.

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A smaller timestep should ensure more consistent and accurate results but comes at the cost of speed.

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The timestep is automatically adjusted during the simulation to optimize accuracy and efficiency.

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There are a number of other settings and options to help you set up your simulation, including:

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Initializing Simulations:

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Before a simulation, InfoWorks ICM undertakes an initialization process.

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This is to prevent you from having to set initial conditions for every object in the network,

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which would be an arduous task, even for a small network model.

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The initialization process aims to get the model to a steady state by using the initial inflows of the simulation.

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In essence, ICM takes a dry network model and starts to inject the inflows into the system.

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It does this by phasing them in over a period of time (default is 15 minutes).

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Once fully phased in, the inflows continue to be injected into the network until the steady state criteria is met,

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that is, no change in depth or flow greater than the defined tolerance.

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At this point, the initialization saves its final state and uses this to begin the hydraulic simulation.

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Sometimes, the initialization process can fail to achieve a steady state, or it may not provide the exact initial conditions that are needed.

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There are a number of options available to help you overcome these issues.

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The initial conditions 1D object is used to assign initial hydraulic values to nodes and river reaches at the start of a simulation.

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To set initial values for level, depth, and velocity within each 2D zone, you can set an initial conditions 2D object.

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Only one of each type of initial conditions object can be included in a run.

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When a simulation is carried out,

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the state of an InfoWorks network at a specified date and time can be saved for use as the initial state in subsequent runs.

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This can be used to break up long simulations into smaller chunks, and it can help prevent data loss for long time-series simulations.

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Episode Collection:

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An episode collection can be used in a run to determine start and end times of events for the simulation.

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This is particularly useful if you want to break up a long set of time-series data into RUNOFF only and full hydraulic calculations.

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Episodes can be automatically generated from statistical report or csv data.

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Timestep Control:

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Timestep Control options are used to define the criteria under which Dry Weather Flow (DWF) mode applies.

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The simulation engine can operate in one of two modes, Storm mode or DWF mode.

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The simulation starts in Storm mode and stays in that mode unless all the criteria that define DWF mode apply.

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Diagnostics:

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Use the run diagnostics to set up thresholds that allow the performance of the simulation engine to be monitored when processing a run.

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The tool also contains reporting options to select the information to be included in the simulation log.

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Once you click to run the simulation, you have scheduling options for where to run the simulation, where to store the results,

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resource usage, and setting a start time for the run.

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The Job Control window displays the order and status of simulations.

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The status of a job currently being run can be viewed in the Job Progress window.

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These two windows contain a variety of helpful tools to help you track, prioritize, re-order, stop, or cancel runs.

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The color-coded icon displayed by the simulation in the database,

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as well of the color of the simulation row in the Job Control window indicate the status of the simulation:

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White: Results unavailable.

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Blue: Results are not currently available, but the local queue contains a job for this simulation that has not yet been completed.

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Red X: The simulation failed.

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Green: The simulation completed successfully.

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Yellow: The simulation completed with warnings.

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Pink: The simulation failed with convergence failure.