Commit 3a818c9d authored by Kilian Lackhove's avatar Kilian Lackhove

Coupling: update userguide

parent 55526089
......@@ -505,4 +505,12 @@ year = {2016}
pages={3128--3144},
year={2006},
publisher={Elsevier}
}
\ No newline at end of file
}
@inproceedings{LaSaJa17,
author = {Lackhove, Kilian and Sadiki, Amsini and Janicka, Johannes},
booktitle = {Proceedings of ASME Turbo Expo 2007},
keywords = {GT2017-63050},
title = {{Efficient Three Dimensional Time-Domain Combustion Noise Simulation of a Premixed Flame Using Acoustic Perturbation Equations and Incompressible LES}},
year = {2017}
}
......@@ -81,12 +81,13 @@ The coupling waits for the file given in the receive function to appear.
\begin{notebox}
The Cwipi coupling is only available when Nektar++ is compiled with OpenMPI and CWIPI
\end{notebox}
The Cwipi coupling uses CWIPI\footnote{http://sites.onera.fr/cwipi/} to facilitate real time data exchange and linear interpolation over MPI.
The Cwipi coupling uses CWIPI\footnote{http://sites.onera.fr/cwipi/} to facilitate real time data exchange over MPI.
See \cite{LaSaJa17} for details.
All data transfers are non-blocking to minimize the computational overhead.
The interface must be enabled with the command line option \inltt{--cwipi} and a unique application name, e.g:\begin{lstlisting}[style=BashInputStyle]
DummySolver --cwipi 'Dummy1' Dummy_3DCubeCwipi_1.xml
\end{lstlisting}
CWIPI uses the current applications and the name of the coupling to identify two peers in cosimulation setups.
CWIPI uses the names of the current application and the coupling to identify two peers in cosimulation setups.
The name of the remote application must be provided by the \inltt{RemoteName} parameter.
Unlike the File-type coupling, a linear interpolation in time is applied to the received fields if non-unity values are set for \inltt{ReceiveSteps}.
\begin{lstlisting}[style=XMLStyle]
......@@ -104,13 +105,12 @@ Unlike the File-type coupling, a linear interpolation in time is applied to the
\end{lstlisting}
Additional options which define the coupling include \inltt{SendMethod}, the method used to retrieve the physical values at the locations requested by the remote application.
The linear interpolation of CWIPI is not used for sending fields, instead the interpolation is implemented in Nektar++ directly.
Available options are \inltt{NearestNeighbour}, \inltt{Shepard} and \inltt{Evaluate}.
The nearest neighbor interpolation gives the best performance at the cost of accuracy.
The last option directly evaluates the expansions using a backward transform, giving superior accuracy while being the most computationally expensive.
The Shepard interpolation can be a good compromise between computational efficiency and accuracy.
When using non-conforming domains, the current application might request values outside of the remote applications computational domain.
When using non-conforming domains, the current application might request values outside of the computational domain of the remote application.
How to handle these not-located points is specified by the \inltt{NotLocMethod} parameter.
When set to \inltt{keep}, the point value is not altered.
With \inltt{Extrapolate}, the nearest neighbor value of the current application is used.
......@@ -128,7 +128,7 @@ Note that this can be very inefficient when using many MPI ranks.
\inltt{SendMethod} & \xmark & \inltt{NearestNeighbour} &
Specifies how to evaluate fields before sending. Available options are \inltt{NearestNeighbour}, \inltt{Shepard} and \inltt{Evaluate}.\\
\inltt{Oversample} & \xmark & 0 &
Receive fields at a higher (or lower) number of quadrature points before filtering.\\
Receive fields at a higher (or lower) number of quadrature points before filtering to avoid aliasing.\\
\inltt{FilterWidth} & \xmark & 0 &
Apply a spatial filter of a given filter width to the received fields. Disabled when set to zero.\\
\inltt{NotLocMethod} & \xmark & \inltt{keep} &
......
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