Computational fluid dynamics, or CFD, is used to simulate the flow characteristics of physical systems. The CFD analyst may use a variety of software in the process required to reach a final representation of system behavior. First, the analyst builds a model of the volume or area of the system to be represented. The model is gridded by one of a variety of methods, and boundary conditions are defined. The boundary conditions constrain the flow solution to include known system behaviors, such as inlet or outlet pressures or known heat and mass flux conditions. The grid and the boundary conditions are used by CFD simulation software as it solves mathematical equations representing the physics of fluid flow. The final result is a data file containing values of variables at each grid point (or cell center) in the model. It is up to the analyst, again with the help of software, to interpret that data into useful information.
The use of CFD in industry requires significant investment and expertise, but the potential return on investment (ROI) from CFD analysis is well documented. The commercial publications of CFD simulation software vendors are filled with successful case studies from real customers demonstrating high ROI for their products. These articles typically cite the cost savings resulting from better analyses, and analyses done without the costly step of physical prototyping.
But is there CFD ROI available beyond what is achievable by the analyst? For this to be the case, the CFD results must be accessible and understandable by non-analysts. Marketers and salespeople could show CFD results to showcase product attributes. Trainers could navigate through CFD results to better explain system behavior to customers. If all levels of the organization could use a single visualization tool, the ability to collaborate and problem-solve across disciplines would also be greatly enhanced. There is significant value to the organization in extending the use of CFD results across the enterprise.
CFD visualization tools offer unique and far-reaching opportunities for extending CFD ROI through the implementation of immersive visualization.
Traditional Visualization: “By Analysts, For Analysts”
Visualization software is used to create graphical representations of the data contained in CFD solution files. While the size of solution files vary according to the complexity of the CFD model, even modest simulations may contain over a million data values, and large models may contain several orders of magnitude more data. Visualization tools traditionally allow analysts to distill the plethora of numbers in a simulation result into useful information on which design decisions can be made.
Most CFD simulation software includes a post-processor for visualization. While not the primary focus of the simulation companies, such tools are geared toward the same analyst creating the CFD model. It is unlikely that other members of the enterprise would have the skill set necessary to launch the simulation software, access its visualization features, create desired visualization scenes and interpret the results.
Third-party software for CFD visualization improves the range of tools available to the analyst, as visualization is now the primary focus for the product offering. These tools have traditionally offered a CAD-like interface and still expect the user to be the CFD modeler or other expert. While clearly any CFD visualization tool needs to provide powerful analytical features, a new approach to visualization is needed to make the information contained in CFD results accessible to a wider audience.
Immersive Visualization: Principles and Goals
Immersive visualization is a paradigm in which the user views and navigates within or around the model with a first-person perspective. Sometimes called “simulated reality,” this perspective encourages the user to experience the data, rather than rely on interpretive skills that may not exist in the non-expert user. By being more experiential, immersive visualization activates the human capacity to relate, evaluate, share, and decide intuitively.
The quality of an immersive experience can generally be gauged by two factors: the user’s level of engagement with the visualization and the user’s feeling of presence in the visualization “world.” When the user’s level of engagement is high, his attention is being recruited and even stimulated by the content being viewed. The visualization experience is dynamic and interactive, and the user has a common sense understanding of the content.
The degree of presence the user feels aids in these characteristics and is largely driven by the successful implementation of the first-person navigation perspective. The quality of presence can be enhanced with stereoscopic viewing on desktop systems or in specialized virtual reality environments. Regardless of the visualization hardware, the feeling of presence is aided by real-time rendering of the visualization scene in high resolution. The faster the graphics display, the more seamless the experience.
Implemented correctly, immersive visualization makes complex geometries and flow behaviors more intuitive to both CFD experts and non-experts. CFD then becomes an inclusive rather than an exclusive technology with wider influence in an organization.
Whether increasing product quality, saving time in design or sales cycles, or increasing product recognition and customer confidence, the avenues to ROI are open when the immersive visualization tool has a few key qualities:
- Realism – Visualization results should be understood on inspection, without a great deal of analytical expertise expected of the user. This feature gives a common sense feeling to the visualization suitable to any audience. Presented in a way that is virtually real, immersive visualization activates the human capacity to relate, evaluate, share, and decide.
- Responsiveness – To explore results seamlessly, to react to requests during working sessions and to deliver live presentations to customers, visualization software needs to provide fast response and real-time rendering of anything the audience wants to see. This “think it, see it” approach is integral to the experience.
- Accessibility – Visualization software is a powerful tool only if it is used and used often. The user interface must be simple and engaging, making the benefits of visualization accessible to non-CFD experts and casual users as well as dedicated CFD engineers and analysts.
An organization has a lot of choices for CFD visualization. Tools that offer real, responsive, and accessible qualities will help an organization analyze, communicate and collaborate on a design in turn saving time and money. The use of CFD in industry requires significant investment, but the potential ROI from CFD analysis is huge. This opens new avenues to CFD ROI, as a single tool can be used across the enterprise.
Karen Ringel, Ph.D. is Manager of Advanced Computing of ACUITIV™ Software, based in Batavia, IL, a leading provider of Computational Fluid Dynamics (CFD) Visualization solutions. Karen can be reached at 630-845-4545 or firstname.lastname@example.org.
An Agitated Tank Reactor in a six-wall immersive environment.