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About CFD Online

CFD Online is an online center for Computational Fluid Dynamics. Services include several discussion forums, a jobs database, a free CFD reference in the form of a CFD-Wiki, a news and announcement forum, a books guide, an events calendar, and a comprehensive annotated link section with pointers to CFD resources around the world. CFD Online's goal is to offer high-quality web services to the CFD community. The site is independent and it is financed mainly by banner-ads.

Today CFD Online is the largest and most popular CFD site on the Internet. During a typical week the web site is visited by more than 71,000 people (unique IP addresses), downloading 410,000 web pages per week. In total there are more than 7,000 web sites around the world with links to CFD Online. In 2015 CFD Online celebrated 21 years of uninterrupted service to the CFD community! CFD Online continues to grow and strengthen its position as the world's leading CFD portal. CFD Online is top-listed by all major search engines and has received many awards over the years.


2015 was a very successful year for CFD Online. The bar chart above shows the 12-month trailing average of the number of web pages delivered from CFD Online per month over the previous 17 years. In June, 2015 we switched to a new and much more modern web-hosting system. We now have several layers of spam filters and various firewalls to automatically block suspicious traffic. We believe that the introduction of more advanced systems to block unwanted traffic has resulted in what looks like a slight decline in web-site traffic, as the diagram above shows. However, the real traffic has most likely continued to grow steadily. We now deliver more than 1.8 million web-pages per month to visitors! The number of unique visitors has increased by 6% compared to the previous year.

Note that these statistics exclude access from robots and common search engines like Google and Yahoo. This is necessary in order to give a true representation of the traffic from real humans. Otherwise the quickly growing traffic from Google and other search engines robots would completely overshadow human visitors.

Visitor Demographics

Visitors to CFD Online come from typical CFD sites from all over the world. The pie chart below shows the traffic distribution across different top-level domains. Further details about where traffic is coming from can be found in the web server statistics report at or in the most recent web-server statistics.

Visitor demographics are similar to last year. The biggest change is that China has dropped from almost 4% of all traffic in 2014 down to less than 1% in 2015. The explanation is most likely that traffic from China is now again hidden behind proxies using anonymous network addresses. Traffic from both US companies and US universities has increased slightly. Traffic from Germany remains very strong and is more than twice as big as the second European country, United Kingdom. The reason is the growth of the German economy combined with the strong usage of OpenFOAM in Germany. More and more companies are now hiding behind anonymous numerical or network addresses and this makes it increasingly difficult to locate where traffic is coming from. On the browser side Chrome (43%) has now passed Firefox (35%) as the most popular browser. Usage of Internet Explorer continues to fall (11%).


The pie chart below shows the relative number of page-downloads for the different services at CFD Online. In total, the discussion forums are still the most popular section, with 57% of all the page-views. The CFD-Wiki has 15%, the Events calendar 7%, the CFD Jobs Database 10%, and the Links section 2% of all page-views.

The strong growth in traffic to the discussion forums, seen in previous years, has continued also in 2015. CFD Online remains the most popular meeting place on the net for free and independent discussions about CFD. Users seem to prefer the open forums at CFD Online over closed forums run by code vendors. The following services are currently available at CFD Online:

News and Announcement Service

The largest free online CFD news service. The news section has 4,600 unique visitors every month and more than 4,600 people are subscribed to the weekly email news-digest.

Discussion Forums

The most popular meeting place on the net for people interested in CFD. The forums have more than 550,000 archived messages in 140,000 threads from the previous 18 years.


CFD-Wiki is intended to eventually become the ultimate free CFD reference and text-book. The content is written collaboratively by thousands of users. CFD-Wiki contains more than 550 articles on various CFD related subjects. Many engineers and students use it as a valuable reference.

Links Section

The links section is very well known in the CFD world and continues to attract many return visitors year after year. It has been the largest collection of CFD links available on the net since it was introduced in 1994. In 2012 a major overhaul of the whole links section was done.

CFD Jobs Database

The CFD Jobs Database is the section that attracts most people. The CFD Jobs Database is visited by more than 1,300 job-seekers every day! It is a very good way to recruit CFD experts. The CFD Jobs Database has had about 200 open positions advertised throughout 2015.

CFD Books Guide

The Books Guide is intended to assist students and professionals in finding good CFD books. The guide includes more than 200 books. After the server upgrade we have had some problems with incompatibilities with the new hosting system. We hope to solve this soon.

Events Calendar

This service is intended to help students and professionals to find CFD related conferences, courses and workshops. The calendar currently includes 44 upcoming CFD events and since the service was opened in 2002 more than 2,300 events have been advertised in it.

Tools Section

The tools section contains online tools useful for CFD engineers and students: Two calculators, a unit converter, a Y+ estimation tool and a tool to convert and estimate turbulent properties.

Feeds Section

The feeds section was launched in 2012; it contains aggregated feeds of CFD news-sources, blogs, vendors, jobs and journals. This service has become an important tool to help people stay up to date.


CFD Online is only responsible for the documents on this server, not for any of the external references. All opinions expressed are personal opinions.

Software and Hardware

CFD Online was moved to a new server in June 2015. We are now running on a virtual server based on Centos KVM technology. This makes it easy to move the site between different hardware servers without any down-time. We have two new hardware servers setup in a failover system, with one production server that normally handles the site alone and one backup server that always stands online ready to take over in case of hardware problems. Our old server struggled a bit when the traffic was high, but our new server handles even the most hectic times excellently. We now have plenty of room to grow and increase our traffic in the future.

Powered by RedHat Powered by RedHat Powered by KVM Powered by Apache Powered by MariaDB, MySQL, PHP

Our new production server has a Xeon E3-1270v3 CPU, 32GB ECC RAM, and two mirrored RAID1 enterprice SSD disks to ensure a quick and reliable delivery of pages.


Please tell us what you think about this site. Contact information can be found on the contacts page. We appreciate any comments or suggestions. It is always nice to get some feedback and not only strange connections from someone.far.away.sirius_b
"I consider it the obligation of scientists and intellectuals to ensure that their ideas are made accessible and thus useful to society instead of being mere playthings for specialists."

- Bjarne Stroustrup, from "Design and Evolution of C++"