Code Verification, Solution Verification and Validation: An Overview of the 3rd Lisbon Workshop

This document introduces the Workshop on Verification and Validation (V&V) of CFD for Offshore Flows, to be held during OMAE2012. It presents a brief introduction to the purpose of Verification and Validation with the identification of the goals of code and solution verification and validation. Within this context, three test-cases are proposed: Case-I of code verification, Case-II of solution verification and Case-III of solution verification and validation. Case-I consists on a 3D manufactured solution of an unsteady turbulent flow. Case-II is an exercise on the canonical problem of the infinite smooth circular cylinder flow at different Reynolds numbers. Case-III is a more complex flow around a straked-riser. The participants are asked to perform at least one of these test-cases. The objectives for the three proposed test-cases are presented, together with a detailed description of the numerical settings to be used, and the results to be obtained and sent to the Workshop organization. At the end some considerations on general conditions, paper submission, deadlines, and encouragements are stated.

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Effective Use of V&V20 Solution Verification Methodology

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C ◽

10.1115/fedsm-icnmm2010-31225 ◽

2010 ◽

Author(s):

Christopher J. Freitas

Keyword(s):

Heat Transfer ◽

Verification And Validation ◽

Code Verification ◽

Flow And Heat Transfer ◽

Time Period ◽

Solution Verification ◽

Particular Solution ◽

American Society ◽

Effective Use ◽

Verification Methodology

Methods for the quantification of numerical uncertainty have been a subject of interest to the American Society of Mechanical Engineers (ASME) and the mechanical engineering community as a whole for over a decade. During this time period, ASME has promulgated three statements of standards for the reporting of numerical uncertainty in archival publications (Journal of Fluids Engineering). This paper summarizes the work that has gone into the specification of these standards and the continuing effort in formulation of methods and procedures for quantifying numerical uncertainty. Specifically, this paper discusses the efforts of the ASME V&V 20 Committee (Verification and Validation in Computational Fluid Dynamics and Heat Transfer) to lay a foundation and structure to verification and validation for fluid flow and heat transfer simulations. Issues and methods related to code verification and in particular solution verification are presented and discussed in the context of the recently released V&V20 Standard.

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Code Verification, Solution Verification and Validation in RANS Solvers

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 6 ◽

10.1115/omae2010-20338 ◽

2010 ◽

Cited By ~ 12

Author(s):

Lui´s Ec¸a ◽

Guilherme Vaz ◽

Martin Hoekstra

Keyword(s):

Turbulent Flows ◽

Verification And Validation ◽

Test Cases ◽

Simple Test ◽

Error Evaluation ◽

Code Verification ◽

Engineering Activity ◽

Solution Verification ◽

The Right ◽

Comparison With Experimental Data

The maturing of CFD codes for practical calculations of complex turbulent flows implies the need to establish the credibility of the results by Verification & Validation. These two activities have different goals: Verification is a purely mathematical exercise that intends to show that we are “solving the equations right”, whereas Validation is a science/engineering activity that intends to show that we are “solving the right equations”. Verification is in fact composed of two different activities: Code Verification and Solution Verification. Code Verification intends to verify that a given code solves correctly the equations of the model that it contains by error evaluation. On the other hand, Solution Verification intends to estimate the error of a given calculation, for which in general the exact solution is not known. Validation intends to estimate modelling errors by comparison with experimental data. The paper gives an overview of procedures for Code Verification, Solution Verification and Validation. Examples of the three types of exercises are presented for simple test cases demonstrating the advantages of performing Verification and Validation exercises.

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An Example of Code Verification in the Simulation of Wave Propagation

Volume 6: Ocean Engineering ◽

10.1115/omae2011-49398 ◽

2011 ◽

Cited By ~ 2

Author(s):

Fahd Fathi ◽

Lui´s Ec¸a ◽

Mart Borsboom

Keyword(s):

Wave Propagation ◽

Numerical Solution ◽

Physical Reality ◽

Verification And Validation ◽

Cfd Modeling ◽

Code Verification ◽

Complex Flows ◽

Solution Verification ◽

The Mathematical Model

Thanks to advances in modeling and hardware the range of applications available to CFD modeling is continuously increasing. As CFD has moved from demonstration of capability to production of engineering results of practical value, there is an increased awareness in the field that Verification and Validation are systematically required. Verification deals with the numerical accuracy of a given set of results. Its object is the assessment of the numerical uncertainty due to discretization and iterative errors of a numerical solution (Solution Verification) performed with a Code that has been previously checked to be free of errors (Code Verification). Both activities are required to ensure that errors are controlled and that quality of the results is maintained. Complementarily, Validation addresses the modeling error, i.e. the comparison of the mathematical model with the (physical) reality. Therefore, it requires comparison with experimental data. Validating CFD results is only meaningful when preceded by carefully verified calculations (Solution Verification) with verified codes (Code Verification). The topic of Verification and Validation is developing and standardized procedures are still under discussion. Nevertheless, there are techniques available to perform careful Code and Solution Verification for flows with engineering relevance. This paper presents a Code Verification exercise for the simulation of wave propagation with a VOF code. Systematically refined grids and time steps are applied in the calculation of waves with a known analytical solution to assess the convergence properties of the numerical solution. The aim of the exercise is to demonstrate the advantages of such exercises for the knowledge of the numerical properties of a code that is applied in complex flows. The study is not a pure Code Verification exercise. Modeling errors introduced by approximate outlet boundary conditions (allowing wave reflections) are also quantified for a linear and a high-order wave. However, these are still based on (numerical) error evaluations for known analytical solutions and so they can still be classified as Code Verification.

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