FluidEarth 2 Launch Meeting Linking Area Type Time Stepping Models (An Overview) HR Wallingford, 18th April 2013 Dr David M Kelly (d.kelly@hrwallingford.com)
What are ‘Area Models’? Overview The OTT2D and Exner models Creating components The need to adapt An example of a simple ‘Adapter’ One- and two-way coupling Representative results for a composition with one-way coupling © HR Wallingford 2011
What are area models? Two-dimensional horizontal type models where values of dependent variables are typically computed on an underlying Eulerian mesh Examples include: SWAN, TELEMAC 2D or 3D, Sisyphe and … © HR Wallingford 2011
OTT2D and Exner OTT2D: 2DH FVM NLSWE solver (cell-centred) EXNER: 2DH FD sediment continuity equation solver (node-centred) © HR Wallingford 2011
Creating the Components Straightforward: Create a (new) engine dll and a dll for the (modified) original code – typically FORTRAN A template (subroutines) for the Engine is available in FORTRAN Original model will need to be modified to remove time-stepping procedure (loop) converted from program to subroutine © HR Wallingford 2011
Why we need to adapt As well as exchanging information in time the we may need to exchange info in space: © HR Wallingford 2011
Simple Adapter © HR Wallingford 2011
Simple Adapter The triangle containing the point is located employing an ‘inpoly’ type algorithm: © HR Wallingford 2011
Simple Adapter © HR Wallingford 2011
One and two-way coupling One way coupling – For water sediment simulations this is often unstable Two way coupling – (Morphodynamic) time-stepping requires thought OTT2D EXNER A OTT2D A EXNER A © HR Wallingford 2011
The Composition – Test Case Nested Mesh System IC simple wet-wet dam-break © HR Wallingford 2011
The Composition – Pipistrelle GUI Setting Up the Variable Transfers: © HR Wallingford 2011
The Composition – Pipistrelle GUI New Adapted Output: © HR Wallingford 2011
The Composition - Results Flow Snapshot one way coupling © HR Wallingford 2011
Conclusions Two Area Models have been successfully coupled with the new frame work using a spatial-type adapter Coupling is intuitive once you have familiarised yourself with the template to construct an engine (removing time-stepping from your own code should be straightforward) It is possible to create ‘stand-alone’ version of compositions that can be run in Visual Studio – very useful for debugging © HR Wallingford 2011
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