Commit 49a95466 authored by Dave Moxey's avatar Dave Moxey

Add user guide entry and update CHANGELOG

parent 3d1ff98a
......@@ -41,6 +41,7 @@ v4.4.0
**FieldConvert:**
- Allow equi-spaced output for 1D and 2DH1D fields (!613)
- Update quality metric to include scaled Jacobian output (!695)
**NekMesh:**
- Modify curve module to allow for spline input (!628)
......
......@@ -427,3 +427,17 @@ year={2011}
volume = {33},
year = {2000}
}
@article{GaRoPeSa15,
title = {Distortion and quality measures for validating and generating
high-order tetrahedral meshes},
author = {Gargallo-Peir{\'o}, Abel and Roca, Xevi and Peraire, Jaime and
Sarrate, Josep},
journal = {Engineering with Computers},
volume = 31,
number = 3,
pages = {423--437},
year = 2015,
publisher = {Springer London}
}
......@@ -122,6 +122,7 @@ possibly also Reynolds stresses) into single file;
\item \inltt{interppoints}: Interpolates a set of points to another, requires fromfld and fromxml to be defined, a line or plane of points can be defined;
\item \inltt{isocontour}: Extract an isocontour of ``fieldid'' variable and at value ``fieldvalue''. Optionally ``fieldstr'' can be specified for a string defiition or ``smooth'' for smoothing;
\item \inltt{jacobianenergy}: Shows high frequency energy of Jacobian;
\item \inltt{qualitymetric}: Evaluate a quality metric of the underlying mesh to show mesh quality;
\item \inltt{meanmode}: Extract mean mode (plane zero) of 3DH1D expansions;
\item \inltt{pointdatatofld}: Given discrete data at quadrature points
project them onto an expansion basis and output fld file;
......@@ -629,6 +630,38 @@ The output file \inltt{jacenergy.fld} can be processed in a similar
way as described in section \ref{s:utilities:fieldconvert:sub:convert}
to visualise the result either in Tecplot, Paraview or VisIt.
\subsection{Calculate mesh quality: \textit{qualitymetric} module}
The \inltt{qualitymetric} module assesses the quality of the mesh by calculating
a per-element quality metric and adding an additional field to any resulting
output. This does not require any field input, therefore an example usage looks
like
\begin{lstlisting}[style=BashInputStyle]
FieldConvert -m qualitymetric mesh.xml mesh-with-quality.dat
\end{lstlisting}
Two quality metrics are implemented that produce scalar fields $Q$:
\begin{itemize}
\item By default a metric outlined in~\cite{GaRoPeSa15} is produced, where all
straight sided elements have quality $Q = 1$ and $Q < 1$ shows the deformation
between the curved element and the straight-sided element. If $Q = 0$ then the
element is invalid. Note that $Q$ varies over the volume of the element but is
not guaranteed to be continuous between elements.
\item Alternatively, if the \inlsh{scaled} option is passed through to the
module, then the scaled Jacobian
\[
J_s =
\frac{\min_{\xi\in\Omega_{\text{st}}}J(\xi)}{\max_{\xi\in\Omega_{\text{st}}}J(\xi)}
\]
(i.e. the ratio of the minimum to maximum Jacobian of each element) is
calculated. Again $Q = 1$ denotes an ideal element, but now invalid elements
are shown by $Q < 0$. Any elements with $Q$ near zero are determined to be low
quality.
\end{itemize}
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