There is a category of Computational Fluid Dynamics (CFD) called Upfront CFD. It typically refers to CFD software embedded in and launched from within CAD systems. Upfront, the term, also implies that it is something that happens before something else, maybe prior to detailed design in the design process - even during the concept design phase. I think the use of the term Upfront CFD is great marketing, but a poor differentiator of the actual CFD software.

Concept Design Phase CFDParametric study of pipe diameter

It has always been the case that CFD is most effective when used prior to detailed design, i.e., upfront during concept design. In fact in the early days of CFD the geometry limitations were so restrictive that CFD was only viable for the analysis of simple shapes - in essence all CFD was upfront. To this day the most effective use of CFD in the design cycle is prior to detailed design - to compare relatively simple designs and aid in the selection of the most promising for further development.

For me upfront defines a process of using CFD, not a software category, the process being to use CFD early and often to reduce your design space to a relatively small number of candidates. While CFD embedded in a CAD system can satisfy this need, so too can most other modern standalone CFD applications.

The purpose of a CAD system is to progress rapidly through to the detailed design phase. CAD systems are optimized for efficiently adding details such as holes, chamfers, etc. The tendency is then to run an embedded CFD analysis at the end of the CAD design process on the detailed design. This is actually the opposite of upfront, more aptly it should be called downback. At this point the details get in the way of the CFD analysis and, more importantly, the scope for changes to improve performance are minimal given the time (money) already invested.

Summary

• Upfront should be considered a process not a CFD software category.
• The most effective use of CFD is upfront in the concept design phase of the design cycle.
• Most modern CFD applications can be used for upfront concept design.