robinknowles

`foamDictionary` Cheat Sheet

Accompanies OnCFD Newsletter #082: Quick edits with foamDictionary

Retrieve entries

# Print the top-level keywords present in this dictionary
foamDictionary system/snappyHexMeshDict -keywords

# Print the addLayersControls sub-dictionary
foamDictionary system/snappyHexMeshDict -entry addLayersControls

How to rename a patch in OpenFOAM using `createPatch`

Accompanies OnCFD Newsletter #144: How to change a patch name

Outline

Need to rename a patch in a meshed & decomposed case? Do the following...

Copy the dictionary below & save it as /system/createPatchDict
Edit the name & patches entries to the required names
Run createPatch -overwrite in parallel to make the change

Shrink-wrapping triangle meshes using CGAL

Accompanies OnCFD Newsletter #147: "It's a(n open-source) wrap"

Here are my "high-level" notes on building a command-line, mesh shrinkwrapper using Alpha Wrap 3 from CGAL.

I did this in an Ubuntu container on a Mac, but you could do similar in Windows Subsystem for Linux or native Ubuntu (or anywhere else that you can grab all of the dependecies).

See the accompanying article for more background 👋

Divergence detection in OpenFOAM using `runTimeControls`

Accompanies OnCFD Newsletter #148: "Divergence Detector"

Here's the copy-paste-able version of the function I use to detect (& end) simulations that are slowly diverging & taking up valuable cluster time.

minMaxU
{
    type        fieldMinMax;

Run Receipts in ParaView

Accompanies OnCFD Newsletter #158

Attached is an example ParaView script to create a "run receipt" summary of your results like this 👇

Straight from the command-line & ready to post into Slack/Teams/WhatsApp

Detecting AWS spot instance interruptions in OpenFOAM

Accompanies OnCFD Newsletter #165

Here's a quick OpenFOAM function that makes running on AWS spot instances a whole lot nicer.

It uses two standard function objects (plus curl) to check whether your instance has recieved a termination notice.

If it has, it stops your simulation & writes your current data.

	# Start from the official Ubuntu Bionic (18.04 LTS) image
	FROM ubuntu:bionic

	# Install any extra things we might need
	RUN apt-get update \
	&& apt-get install -y \
	vim \
	ssh \
	sudo \
	wget \

	// OpenFOAM v2112 function using sampledSurfaces for patch/surface export
	// Includes:
	// - multiple file formats;
	// - point-data export;
	// - near-wall interpolation;
	//
	// Can be tested on motorBike tutorial data, using:
	// postProcess -func sample -latestTime

	sample

	/--------------------------------- C++ -----------------------------------\
	\| ========= \| \|
	\| \\ / F ield \| OpenFOAM: The Open Source CFD Toolbox \|
	\| \\ / O peration \| Version: v2206 \|
	\| \\ / A nd \| Website: www.openfoam.com \|
	\| \\/ M anipulation \| \|
	\---------------------------------------------------------------------------/

	// Calculate lift force coefficient acting on the motorbike patch group
	// Then "bin" that data along the X & Y axes to create a force x-ray

	# state file generated using paraview version 5.11.1
	import paraview
	paraview.compatibility.major = 5
	paraview.compatibility.minor = 11

	#### import the simple module from the paraview
	from paraview.simple import *
	#### disable automatic camera reset on 'Show'
	paraview.simple._DisableFirstRenderCameraReset()