# Community Wiki: Quick Tutorial

The documentation project LBM Wiki is written and maintained by the project committee. However, the Wiki also contains a community branch in which, similarly to Wikipedia, visitors may contribute their own content.

## Purpose of the Community Wiki

The LBM Community Wiki can be used to present information about and around lattice Boltzann. This can for example be a summary of a well-known topic, a presentation of ongoing research, or a discussion on a controverted topic. Thanks to the ability to typeset formulas and source code, and the possibility to upload pictures and programs, the Wiki is also useful as a support for extended discussions on the forum.

You are welcome to present your personal research on these pages, and to create links to your work, including links to commercial products. However, please stay focused on lattice Boltzmann and refrain from excessive advertising. If you plan on referencing your journal publications, you are encouraged to submit a BibTeX file in order to add it to the LBM Wiki article list.

Note that unlike Wikipedia, the LBM Community Wiki is not restricted to well known or generally accepted facts. Instead, personal opinions and incomplete materials are welcome.

## Create an account

Only registered users (registration is free) can edit content on the Community Wiki. To register, click on the Login button on the bottom right of the screen, and then on the Register link. Your e-mail address, which is required for registration, is handled confidentially. It is not distributed nor included in any mailing list.

LBM Wiki is run by DokuWiki, which has a simple yet powerful syntax. To understand the principles of the Wiki, one can draw an analogy with LaTeX: all content possesses a pure text view (similar to a LaTeX source file) and a layout view (similar to the DVI or PS or PDF produced by LaTeX). However, the Wiki syntax tends to be much simpler, and no compilation step is required. Instead, the layout view is automatically generated from the source for each visitor of the Wiki pages. To get a first impression of how the Wiki syntax looks like, click on the Show page source link on the bottom left of the current page, and admire a pure text view of the page you are currently reading.

To create or modify Wiki content, log in through the Login button on the bottom right of the screen. Then, navigate to the Community Wiki, which you may want to open in a new tab by Ctrl-left-clicking on the following link: community:main. As you have edit permission, the Show page source link is replaced by Edit this page. Alternatively, you can edit individual paragraphs by clicking on the corresponding Edit buttons.

Next, create a new page to avoid flushing your content directly onto the main page. This is most easily done by creating a link to the not-yet-existing page. To create the page lbm_simulation_of_pacific_ocean, edit the main page and enter the following text at an appropriate place:

[[community:lbm_simulation_of_pacific_ocean|Pacific Ocean simulation with LBM]]

and save your modification. As the Wiki switches to layout view, click on the link your created (it is red because your page doesn't exist yet), and choose Create this page. The page is situated in the namespace community, which was ensured by prepending this name, followed by a colon, to the page name. Only pages in the community namespace may be edited by visitors.

## Typesetting text, code, and mathematical formulas

Basic text formatting includes writing headlines, bold/italic/underlined text, ordered and unordered lists, etc. To remember the syntax, use the quickbuttons displayed on top of the editor. Get a layout view of your page using the Preview button before saving. To experiment with the Wiki without modifying your page, make your first steps on the playground.

The code environment is used to format short code snippets. For example, type

<code c++>
T poiseuilleVelocity(int iY, LBunits<T> const& converter) {
T y = (T)iY / converter.getResolution();
return 4.*converter.getLatticeU() * (y-y*y);
}
</code>

to get the following formatted output:

T poiseuilleVelocity(int iY, LBunits<T> const& converter) {
T y = (T)iY / converter.getResolution();
return 4.*converter.getLatticeU() * (y-y*y);
}

For long code pieces or full programs, the code file can be uploaded and made available, as explained in the next section.

Mathematical formulas are typeset using a syntax very similar to LaTeX. Typing

$f_i(x+c_{i} ⋅ \delta t,t+\delta t)-f_i(x,t)= -{1}/{\tau} (f_i(x,t)-{f_i}^{eq}_(\rho,u) )$

gets you the following output:

$f_i(x+c_{i} ⋅ \delta t,t+\delta t)-f_i(x,t)= -{1}/{tau} (f_i(x,t)-{f_i}^{eq}(\rho,u) )$.

Use the upload quickbutton on top of the editor to upload pictures, source code, or other files. Pictures can be directly inlined in the page:

The picture title is displayed as a tooltip in most browsers. To align the picture, use left or right whitespaces. Here is a centered version of the OpenLB logo:

Note that uploads are restricted to a maximum size of 100 kB per file. Furthermore, upload is disallowed for many file types, including source files for common programming languages. Both restrictions can be circumvented by using data compression and uploading .gz, .zip, or .tgz files.

## Authorship of Wiki content

While an online encyclopedia like Wikipedia collects well-known facts on various topics, a scientific Wiki like LBM presents also ongoing research and personal opinions with a certain degree of subjectivity. It is therefore often useful to mention the name of the author of Wiki content. In this way, it is easier to distinguish different approaches and schools of thought, and possibly to contact the authors on the forum or on conferences with further questions.

To connect the Wiki content with the main author, you may therefore want to start a new page with a line like the following:

Main author: Name,

where Name can be your real name, or your forum alias. This is not a requirement though, and it is perfectly fine to write anonymous content.

When modifying or adding to a page of which the main author is known, politeness requires that you mention that the addition is due to a different author, unless you are correcting an obvious typo. Use for example a syntax like the following: