COMPIT 2010 in Gubbio - TUHH

Aspects of Selecting the Appropriate CAD and CFD Software
Volker Bertram, Germanischer Lloyd, Hamburg/Germany. volker.bertram@GL-group.com
Patrick Couser, Formation Design Systems, Bagnères de Bigorre/France. patc@formsys.com
Abstract
This paper discusses some general aspects to be considered when selecting CFD software. A German
industry guideline for CAD software selection and implementation within the specific context of CFD
systems in the marine industry is presented. A systematic procedure for software selection is described.
At the core of the selection scheme is a trade-off between costs and benefits in the long-term;
the importance of staff costs is underlined.
1. Introduction
In highly complex industries, such as modern shipbuilding, CAD (computer aided design) systems
play a fundamental role in achieving and maintaining a competitive advantage. Central design systems
use an assortment of simulation software to assess design alternatives. Fach (2006) illustrates the
variety of simulation software used in the modern ship design process. This includes advanced flow
simulation software grouped together under the term CFD (computational fluid dynamics).
The procedures described in this paper are neither original nor are they limited to the selection of
software packages for the shipbuilding industry. Many of the recommendations are adapted from previous
consulting experience and from guidelines relating to software selection in the German automotive
and mechanical industry, VDI (1990). However, the selected topics and examples focus on software
used widely in the shipbuilding industry. The term CAD will be used in a wide sense, including
the broad spectrum of all simulation software used in the design process.
2. In-house or Outsource
A key decision, to be made early on in a project, is whether the engineering task should be performed
in-house or outsourced: i.e. should the work be carried out by one’s own company (requiring the development
or licensing of specialised software) or should the work be outsourced to specialists external
to the organisation. If the engineering task is outsourced, the software selection decision is shifted
to the consultant providing the service.
Since the focus of this paper lies on the software selection process, we will only briefly describe the
reasoning behind outsourcing engineering tasks, in particular CFD simulations. See Bertram (1993)
for a more detailed discussion; despite the progress in CFD systems, the fundamental economic considerations
have not changed.
If CFD calculations are undertaken infrequently, there can be large savings to be made by outsourcing.
This is due to the high fixed costs of hardware, software and especially training (which is often
not considered at all). However, if several computations are performed annually, considerable economies
of scale can be achieved: if ten computations are performed per year, the unit cost will be reduced
by 80% compared with the unit cost if only a single computation is performed in the same period.
This makes CFD computations for occasional, or first-time, users far more expensive than buying
the service from third parties who themselves can profit from these considerable economies of
scale due to frequent usage.
For the rest of this paper we shall examine how to assess the cost of in-house analysis.
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