VERIFICATION AND VALIDATION

### Introduction

Verification and Validation (V&V) aims at quantifying numerical and modelling errors in Computational Field Simulations, i.e. numerical solutions of mathematical models that describe physical processes involved in Engineering applications.
The MARIN cooperation with Instituto Superior Técnico (IST) started in 1986. The development of Computational Fluid Dynamics (CFD) tools for the simulation of viscous flows of high Reynolds numbers has been one of the main topics of the research work. When the PARNASSOS CFD code started to be used routinely to study the flow around ship hulls at model and full scale Reynolds numbers, the quantification of the numerical and modeling accuracy of the CFD tools became one of the priorities of the MARIN-IST cooperation. These pages about Verification and Validation (V&V) contain links to papers and Workshops and tools related to Verification and Validation that have been written, organized and developed since 2000 that can be useful for the Modeling and Simulation community.
Verification and Validation (V&V) aims at quantifying numerical and modelling errors in Computational Field Simulations, i.e. numerical solutions of mathematical models that describe physical processes involved in Engineering applications.

### Definitions

Although there are several definitions available in the open literature, simple definitions of V&V are given below.

Verification
Verification can be summarized as “Check if we are solving the equations right”, i.e. a mathematical problem that focus on the quantification numerical errors. However, it actually contains two different types of activities:
1. Code Verification that deals with coding mistakes, i.e. check that there are no “bugs” and the check of the consistency of the discretization techniques used in the computational models.
2. Solution Verification that aims at estimating the numerical uncertainty of solutions for which the exact solution is unknown.
Validation
The simplest way to describe Validation is to say that it corresponds to “Check if we are solving the right equations”. It is related to the quantification of modelling errors, i.e. the difference between the outcome of a mathematical/computational model and the physical reality. In its simplest form, it requires a solution of a mathematical model and experimental measurements. Unfortunately, none of these quantities are exact due to numerical, input parameters and experimental errors, which are often unknown. Therefore, the estimation of the uncertainties that characterize these errors is a fundamental part of any Validation exercise.

Contact Serge Toxopeus

Team leader CFD development / Senior Researcher

Publications
Paper
OC6 Phase 1b: Validation of the CFD predictions of difference-frequency wave excitation on a FOWT semisubmersible

Dec 1, 2021

During the previous OC5 project, state-of-the-art mid-fidelity engineering tools for floating wind systems were found to consistently underpredict ...
Paper
Evaluation of RANS and SRS methods for simulation of the flow around a circular cylinder in the sub-critical regime

Jul 3, 2019

This work investigates the modelling accuracy of distinct Reynolds-Averaged Navier-Stokes (RANS) equations and Scale-Resolving Simulation (SRS) ...
Paper
Iterative Errors in Unsteady Flow Simulations: Are they Really Negligible?

Oct 3, 2017

This paper summarizes the main results of this first Workshop on Iterative Errors in Unsteady Flow Simulations. It presents a brief description of ...