How to Plan a CFD Analysis

De Souza, A

First Published - February 2003
Softback, 45 Pages

Computational Fluid Dynamics (CFD) is now widely used in industry to simulate a very large range of industrial flow problems. It is used by engineers both as a complementary design and development tool and to help understand complex flow phenomena in existing flows. CFD can be an expensive and time-consuming technology. It should be applied with care and only to projects to which it can provide significant added value. Inappropriate use of such analysis tools can produce inaccurate and even incorrect results. Careful planning should minimise the risks of this occurring and ensure that the customer is aware of the level of accuracy that may be expected.

To make the most use of this powerful tool it is necessary for the analyst to understand why a simulation is required, what output data are required, the necessary accuracy of the output data and at what locations those data will be required. Planning is necessary to enable the most suitable models for the flow under consideration to be selected and to ensure that any simplifications made are not likely to have a significant impact on the required output data.

The amount of effort required for analysis planning will vary considerably depending on the type of analysis being conducted. Less planning is required for quick ‘look-see’ analyses for which a low level of accuracy and fewer data points are required. Large-scale analyses for which significant accuracy and several flow or geometrical variations are required will, of course, require considerable planning.

This booklet will assist in planning what is required for an analysis and in assessing the time and resources that should be allocated to the project. It will also help with the development and maintenance of CFD analysis quality systems. The analyst is encouraged to consider the whole process at the start of the analysis procedure and to plan the work to ensure all the requirements are successfully achieved. In the following chapters the various stages are mapped out and described in limited detail with emphasis on areas that require particular care.

The following publications provide further reading:

• NAFEMS Quality System Supplement to BS EN ISO 9001 Relating to Engineering Analysis in the Design and Integrity Demonstration on Engineered Products, issue 2.0, 1999, NAFEMS ref. R0013
• NAFEMS Quality Assurance Procedures for Engineering Analysis, NAFEMS ref. R0064, 1999, Smith, J.
• Best Practice Guidelines, Version 1, ERCOFTAC Special Interest Group on “Quality and Trust in Industrial CFD”, ERCOFTAC 2000, Editors Casey, M., Wintergerste, T.
• NAFEMS Management of Finite Element Analysis – Guidelines to Best Practice, NAFEMS ref. R0033, 1995, Beattie, G.A.
• CFD Analysis: Guidance for Good Practice, NAFEMS ref. R0063

It should be pointed out that a small booklet of this type cannot be fully general for such a diverse field. Each analyst will have to adapt and develop the suggestions presented here to the applications and circumstances with which they are faced. This booklet is not intended to constrain the use of CFD, rather to enable it to be used safely and with confidence in the ever-growing range of applications to which it is being applied.

Contents

1. Introduction

2. Overview

3. Quality Procedures

4. Analysis Request

5. Assessment of Analysis Requirements

6. Analysis Specification

7. Geometry creation

8. Grid generation

9. Model Set-Up

10. Solution Process

11. Solution Verification

12. Analysis Validation

13. Non-Conforming Analyses

14. Post processing

15. Report writing

16. Data Control and Storage

17. Project Management

18. Conclusions

References

Appendix A: Stages in a CFD Analysis

Appendix B: Templates for Alternative CFD Request Sheets

Appendix C: Template for a CFD Solution Sheets