Verification Methodology

The AFT Arrow software is a compressible pipe flow analysis product intended to be used by trained engineers. As a technical software package, issues of quality and reliability of the technical data generated by the software are important. The following description summarizes the steps taken by Applied Flow Technology to ensure high quality in the technical data.

1. Comparisons with open literature examples

Open literature examples for compressible flow in pipe networks are very hard to find. However, examples for single pipe systems are more common. AFT Arrow has been compared against a number of single pipe examples with good agreement.

2. Software checks results to ensure mass and energy balance

AFT Arrow’s network solution method is based on a popular iterative method to solve pipe network systems. The method is known as the Newton/Raphson method. The methods that are used in AFT Arrow iterate on the governing equations to obtain a balanced mass and energy in the system. After a solution is obtained, a final check is made by the software whereby the mass flow and energy flow into each node is checked for balance. If a balance is not found, the user is warned in the output. This ensures that the results generated by the software agree with the applicable fundamental equations.

See the AFT Arrow Help site for more information.

3. Hand/spreadsheet checks of the solutions confirm agreement with fundamental equations

AFT Arrow uses a marching method to solve the fundamental equations of compressible flow for each pipe. The results can be exported from AFT Arrow and checked by hand calculations or spreadsheet to evaluate agreement with the original equations. This has been performed by AFT and agreement has been demonstrated repeatedly.

See the AFT Arrow Help site for more information.

4. AFT Arrow offers three independent solution methods which can be cross-checked

AFT Arrow offers three independent solution methods. Each is optimized for a particular application, but in many cases all three methods can be used to solve the same system. In such cases, agreement between the three methods gives confidence that accurate solutions have been obtained.

See the AFT Arrow Help site for more information.

5. AFT Arrow predictions agree with AFT Fathom predictions for incompressible flow

For incompressible and moderately compressible gas systems, AFT Arrow results can be compared against those generated by AFT Fathom. In such cases agreement between AFT Arrow and AFT Fathom has been demonstrated repeatedly.

6. Software has been used in industry since September, 1995 demonstrating repeated agreement with other methods and data

AFT Arrow became available in September, 1995, and is currently being used by companies in the following industries: chemical, petrochemical, power generation, architectural, ship construction, aerospace, and pharmaceutical. Since its release, AFT Arrow has been applied to numerous gas systems with various working fluids and has repeatedly demonstrated agreement with data and other analysis methods. In addition, Applied Flow Technology issues maintenance releases of the software periodically to improve performance and correct any problems that may have been discovered.