One of the challenges facing any naval architect or designer is establishing the validity of a new design within the constraints of time, cost and access to the most advanced computation fluid dynamics (CFD) tools. To address this problem, Dutch naval architecture firm Van Oossanen has developed a new online tool that it believes will prove invaluable for conducting preliminary CFD work on hulls.
Accessed through a dedicated website – CFDanalysis.com – the online tool came from the idea that it is difficult and expensive to use CFD in conventional design scenarios. “We wanted to make the possibilities of CFD more available to the rest of the world independent of your knowledge of CFD,” Niels Moerke, managing director of Van Oossanen tells SuperyachtNews. “It was quite some work for us but it was doable to make an automated process, and it’s a good way – also for young people – to get familiar with these types of calculations and to understand the full power of CFD.”
The system is simple to use. A user sets up an account on the cfdanalysis.com website and uploads the hull’s geometry along with length, speed and displacement, which is stored in a separate part of Van Oossanen’s computing cluster to ensure confidentiality and anonymity. “Our system then picks it up and creates the full mesh that you need for CFD around the geometry,” Moerke explains. “The system then analyses the hull in our full CFD software and generates pictures and the resistance values which go into a full 3D PDF report. Within a day or a day and a half the customer can download the report within the portal.”
The tool makes use of the full capabilities of Van Oossanen’s CFD software and extensive computing capability, which is among the most advanced in the marine industry. With 265 cores, it’s computing backbone is capable of calculations for a 128 million cell mesh – although that level of detail is generally not necessary for normal calculations.
Aimed squarely at other naval architects, yards who want a little more independence, ship owners, students and a wide range of maritime professionals, the cost of running a design through the CFD portal is set at a flat fee of €900. “The costs are lower [than a full consultation] for a number of reasons,” says Moerke. “You don’t get specific advice on the hull lines, for example, or if there are specific problems within the hull geometry or with flow separation etc you won’t be notified on that, unlike if we took a hull shape and made a full report in-house with recommendations on the hull shape and where to fine-tune it. It’s a different process, a bare run – you get the results and we assure that they are valid and accurate, but what you do with the results is up to the user.”
At the moment the webshop portal is limited to one service, meaning you can analyse a hull, but if you want more detailed analysis on a bowthruster opening, skeg and appendages then you would need to go through a conventional process with Van Oossanen.
However, such a cost-effective solution has considerable benefits for the wide-ranging potential clientele. “The strength is that you can very easily use this in, for example, the preliminary design stage in which you have to give numbers for resistance, installed power and speed,” Moerke explains, “and using this type of CFD is much more accurate than an empirical model which is very custom in ship- or yacht building. You can easily fine-tune the answers using CFD and since it only takes a day or a day and a half it’s easily done during the preliminary design stage.”