2D Linear Structures in Infoworks ICM

Duncan Kitts

IntroductionNew functionality added to Infoworks ICM.ICM 2.5:-

Base Linear Structures eg Walls/WeirsICM 3.0:-

Sluice Linear Structures eg Sluice gatesMany Applications:-

Urban flow routes2D BridgesSpatially-varying EmbankmentsDam Breaks

Surface/Floodplain ModellingTraditionally 1D approaches to floodplain and surface modelling.

Current move towards 2D floodplain and surface modelling.

Heavily reliant on Ground Model data.

Any structures added as 1D.

Ground ModelsGround models commonly from LiDAR or other airborne derived elevation model.Ground models:

Synoptic2-Dimensional

First surface.Therefore 2D models commonly still require 1D elements.

2D Ground ModelsCan miss important flow routes.LiDAR picks up first surface.Urban and Rural Areas. Flow

Route

Urban Area Examples

Rural Examples

Traditional Approaches‘Burn’ opening into the ground model or 2D mesh.No surcharge effects.No deck flow.

Traditional ApproachesAdd a 1D structure connected to the 2D domain.Traditionally a point coupling via a single element.ICM 2.0, Inline banks allow a linear coupling via a number of elements.Loss of momentum and potential mass balance errors.

2D Sluice Linear StructureConstriction to flow represented in 2D.Rectangular in shape (further shapes added in ICM 3.5).Headloss Coefficients.Lateral friction coefficient.Reverse Flow.Blockage Percentage.

2D SluiceAdded as a linear feature.Part of the 2D mesh.Calculated on an element face by face basis.Can be associated with a 2D Base linear structure, eg a wall/weir.2 Layer flow.

2D River Example• Semi-arid area in Southern Europe.• 26km of 2D River (~80,000 elements).• 7 Road Bridges.

2D River ExampleOriginally 7 1D Bridges connected to 2D via Inline Banks.

~4.25hours (with GPU) (MB=-0.0048%).

Converted to 2D Linear Structures.~5Hours (no GPU) (MB=0%).

2D Walls/WeirsEither Free flow or weir controlled flow (thin plate or broad crested).Specify porosity:-

0 – no flow allowed though1 – as if wall does not existValue between 0 and 1

Specify Crest Level:-InfiniteHeightLevelIrregular

Embankment/Flood WallsIrregular Elevation, unlike:-

WallsPorous Walls

Collapsing WallsSame as porous walls.Remove wall during simulation:-

Fully Partially

Wall Removal triggers:-DepthElevationVelocityUnit FlowTotal headForce per unit length

Partially Collapsing Walls

Plan View

Cross-Section

View

Fully Collapsing Walls

Plan View

Cross-Section

View

Future DevelopmentsGPU modelling of 2D Structures.Non-rectangular/User Defined Sluice Shapes.Real Time Control of Sluices.Time-varying crest levels for Breach Modelling.

ConclusionsNew 2D Structure functionality within Infoworks ICM.Allow full 2D modelling of:-

River channelsFloodplainsUrban surfaces

Wide range of applications.Potential use to simulate dam break.