If I post my works in the CFD-Wiki will I later be able to publish it in a paper or a book?
In general, yes! By submitting your works to the CFD-Wiki you release that version under a free GFDL license (see Project:Copyrights for more information). The GFDL license is not an exclusive license and as the original author you always keep the copyrights to your own works. Hence, you can also release your own works under a different license, for example a commercial license as commonly used by publishers. The only problem that might occur is if the publisher requires an exclusive license. The version of your works that you have released under a GFDL license and added to the CFD-Wiki can not be retracted since the GFDL license is non-revocable. This is normally not a problem though since you will usually re-work and extend your works significantly before publishing them commercially. Most publishers are happy with this. Having previous versions of your work in the CFD-Wiki might even be good publicity for your later publications.