CFDesign user’s guide

CFdesign represents a major step forward for all engineers responsible for prod
ucts that incorporate fluid flow and heat transfer. CFdesign is a design tool, and
incorporates many features that make flow analysis a valuable and practical part of the product design process.
CFdesign has been developed from day one for multi-faceted product development teams using MCAD tools such as Pro/Engineer, CATIA, Autodesk Inventor, SolidEdge, Unigraphics, Solid Works, and many others. Powered by proprietary numerical techniques and leading-edge computational methods, CFdesign features a true associative relationship with components and assemblies, and automatically applies the optimal mesh required for accurate fluid and thermal simulations.

The Basic Process
This section briefly summarizes the process of setting up, running, and visualizing results with CFdesign. Starting CFdesign from various CAD systems with the direct launchers and from the Desktop is discussed in a prior section. After the analysis is named, the following general steps must be taken:
1. On the Feature Tree, set the Analysis Length Units system.
2. Using the Loads Task Dialog, apply boundary conditions and, if required, initial conditions.
3. In the Mesh Task Dialog, apply mesh sizes to volumes, and if required for local
refinement, to surfaces and edges.

The User Interface
This chapter describes how to use the CFdesign User Interface without going into
the technical specifics of the fluid flow and heat transfer analysis process. (This is
discussed in later chapters.) Details about customization, the tool buttons, the feature tree and dialog regions as well as entity selection and groups are covered in this chapter.

CFdesign has very strong ties to most of the CAD tools used in industry today. By
using the same geometry engines found in these CAD systems, CFdesign reads the native model without the need for Step or IGES translations. Parametric changes to the geometry are read directly into CFdesign, and model settings from similar analyses are automatically applied to the modified geometry.
This functionality allows two things to occur very easily: The first is that multiple
design alternatives can be analyzed very easily–without having to go to great
lengths to fix IGES or Step translations for each “what if” scenario. The second is
that corporate PLM/PDM initiatives are supported–geometry manipulation occurs ONLY in the CAD system, where it can be tracked and archived. When geometry is manipulated in a third party system (such as many of the other CFD tools),changes often get lost, or simply have to be re-created in the CAD system–thereby doubling the work. With CFdesign, such issues are not a problem.
This chapter describes the type of CAD geometry needed to successfully run a flow analysis. Guidelines for what is needed, techniques for how to obtain it, and troubleshooting tips are presented. Guidelines specific to Pro/Engineer and to Parasolid/Acis based CAD systems are discussed

This chapter describes both the physical significance of loads as well as how to the correctly assign them in the CFdesign user interface. Loads can be classified into two categories: boundary conditions and initial conditions. The former can be a known velocity or flow rate at an inlet, a specified temperature, or a heat flux, for example.
Boundary conditions are enforced through the entire course of an analysis. Initial
conditions, however, are often applied to larger regions of a geometry, but are only enforced at the beginning of an analysis. Initial conditions are often the starting point for a transient analysis.

Mesh Sizes
Prior to running a CFdesign analysis, the geometry has to be broken up into small,manageable pieces called elements. The corner of each element is called a node,and it is at each node that a calculation is performed. All together these elements and nodes comprise the mesh (also known as the finite element mesh).

Materials are physical substances, and are key to the CFdesign analysis. There are eight distinct material types available in an analysis: fluids, solids, internal fans,centrifugal fans, resistances, check valves, rotating regions, and moving solids.Each material type will be discussed in this chapter

The CFdesign Motion Module provides the ability to analyze the interaction between solid objects in motion and the surrounding fluid. The effect of the motion on the fluid medium as well as the flow-induced forces on the object can both be analyzed efficiently and quickly

The Options dialog is used to set basic conditions and parameters of the analysis.

Analyze, the model should be set up and ready to run. The Analyze dialog con
tains controls to run the analysis, and also launches the Convergence Monitor. The Convergence Monitor allows an easy way to monitor the performance of the calculation. The Fast Track Option is also discussed.

The Review dialog contains tools to help assess convergence throughout the entire calculation domain as well as at individual monitor points. Additionally it provides access to several files that contain summary, status, and results information. Use the Review dialog to animate multiply saved results sets or time steps as well as produce Reports that summarize the analysis setup and results.

Viewing Results
CFdesign has a powerful set of results visualization tools to help view, extract, and present analysis results quickly, easily, and efficiently. An integrated feature tree lists display entities, and several ways to output graphical images and data make communicating your analysis results with other members of the design supply chain very easy.

Results to FEA Loads
CFdesign results can be applied as boundary conditions for FEA analyses using several popular FEA tools: Nastran, Abaqus, Ansys, Pro/Mechanica, I-DEAS, and Cosmos, as well as FEMAP. This capability showcases one of the strengths of the finite element approach, in that results can be shared across analysis platforms and used for subsequent calculations quickly and easily. The ability to transfer results to loads in this manner greatly strengthens the bond between flow and structural analysis, making for a more comprehensive and useful analysis suite. As a critical element in this suite, CFdesign allows flow analysis to be an integral part of the product design process.

Most of the description in this guide has been about setting up, running, and post
processing an individual analysis. CFdesign has made this process very easy. In
fact, if product design was accomplished with just one or two analyses, our work
would be done. The reality of the situation however, is that design engineering
requires many analyses and a great deal of information to attain that much sought after final design.

Analysis Guidelines
This chapter presents guidelines for various types of flow analyses. While the previous chapters in this Guide discussed the general operation of the software, this chapter discusses some of the specific physical details of various flow conditions.
The suggestions offered should be used in conjunction with the Examples Manual.

CFdesign has several innovative methods for leveraging computing power to ensure maximum performance and efficiency. The basic CFdesign architecture is built upon a client-server model, which serves as the foundation for the Fast Track and Queuing operations. By separating the User Interface from the Solver, it is possible to shut down the interface after the analyses is started. This foundation also provides the basis for Fast Track–a way to run analyses on a networked machine different from the machine that contains the original model


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