scope:

Scope and Objectives of this Recommended Practice

This Recommended Practice is written for developers and users of CFD codes, their managers, and those who make decisions based on results from CFD simulations. This Recommended Practice provides the relevant definitions, relevant theoretical background, relevant computational procedures, and consensus general procedures for code verification. The document emphasizes practical aspects of the code verification process. The main body of the document is intentionally brief, with details and derivations relegated to appendices, and with references provided for additional or more detailed coverage of the subject.

The scope and objectives of this Recommended Practice are as follows:

• Explain what code verification is and explain its role in deciding whether a computational code is fit for a particular purpose.

• Explain and increase awareness of the importance and need for code verification, especially when the CFD code will be used in mission-critical or high-consequence decision making.

• Identify who is responsible for ensuring that code verification has been carried out and who should carry out the actual work of code verification.

• Review the theoretical background and the discrete solution criteria that are relevant for code verification, including the definitions of consistency, stability, convergence, and order of accuracy.

• Explain how to plan a code verification program, starting from the selection of a suitable reference solution, all the way to compiling, interpreting, and documenting the results.

• Provide guidance on how to determine the observed order of accuracy.

• Demonstrate how to carry out code verification for each of the three acceptable categories of reference solution; namely, (1) traditional exact analytical solutions; (2) exact manufactured solutions; and (3) benchmark computational solutions.

• Provide references to literature for more detailed coverage of code verification.

The concepts and practice of code verification have matured to a level that allows the formulation of a systematic process and an engineering recommended practice for code verification. Any systematic process and any recommended practice for code verification should nevertheless still allow for improvisation for special cases and for handling various potential complications.

This Recommended Practice is organized as follows: Section 1 defines code verification, explains its importance, and outlines its role within the overall VVUQ process for CFD. It also identifies the individuals who should carry out code verification and those who should ensure that it has been carried out before using the computational results. It also outlines the objectives, contents, and scope of this Recommended Practice. It also provides a brief overview of the code verification process. Section 2 provides the theoretical background and the fundamental definitions and concepts related to code verification. Section 3 provides the recommended code verification process for CFD codes and explains the criteria for successful code verification. Section 4 provides a summary of this Recommended Practice and its main conclusions and recommendations. Appendix 1 provides examples of code verification using exact analytical solutions, exact manufactured solutions, and benchmark computational solutions, and discusses how to choose such solutions for code verification. Appendix 2 presents recommendations to managers, users, and developers seeking to adopt sound and effective code verification principles and practices. Appendix 3 outlines the method of manufactured solutions and its use in code verification.