Flownex Simulation Environment

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Verification and Validation of Flownex

Verification and Validation (V&V) is a crucial part in the development of Flownex. In the V&V process of Flownex, “Verification” is the process of ensuring that the controlling physical equations have been correctly translated into computer code or in the case of hand calculations, correctly incorporated into the calculation procedure. Validation is defined as the evidence that demonstrates that the code or calculation method is fit for purpose. This includes the confirmation that the results from the verified model agrees with the benchmarks.

To ensure that all phenomena for each component in Flownex are validated for the various extremities is a comprehensive exercise. Furthermore, V&V of the individual components as well as integrated systems of components for both steady-state and dynamic analysis are required.

The main focus of the Flownex V&V process is to perform effective V&V of complicated phenomena using the least possible validation cases. This is all done in a transparent and traceable manner according to regulatory guidelines and relevant international standards.

V&V forms part of the overall Flownex development process and includes the verification activities that form part of the software engineering process, as well as all related verification that is done as part of the derivation and implementation of the theory for component models or model enhancements.

Tools used in the verification of Flownex include an implemented ISO 9001:2000 quality management system at M-Tech Industrial, the code developers, test plans and procedures, code reviews, user testing, automated testing and regression testing. Validation of Flownex Nuclear is performed by comparing the results of the implemented theoretical models in Flownex Nuclear with benchmark data obtained from appropriate methods or sources such as analytical data, experimental data, plant data and data obtained form other codes such as Spectra, XNet and Star CD. To further enhance the Flownex V&V effort and to ensure that the Flownex capabilities comply with the latest requirements on HTGR analysis, M-Tech is an active participant in international standard problems and conferences, like CRP-5, ICAPP and HTR-TN.

This validation case study demonstrates the verification and validation of the Flownex ANSI control valve element. The simulation of an ANSI control valve is stipulated by the ‘American National Standards Institute’ in the document ‘Flow Equations for Sizing Control Valves’

 

 

The purpose of the volume blow down validation case is to validate the Flownex node transient pressure response. The nodes in Flownex are the endpoints of elements and serves to connect elements in the network. The nodes are also the centers of the control volumes in the network CFD approach employed in Flownex. This means that mass conservation is enforced on the nodes, and momentum conservation is applied across the elements.

 

 

The pump model implemented in Flownex is a practical model giving the user the functionality to model centrifugal fans or pumps. The purpose of this validation case is to verify the operation of the pump model over the full range of the pump chart. An analytical pump comparison was used as benchmark.

 

 

This validation case study demonstrates the validation of the Flownex pipe element with experimental results of a fast transient in a branched network. A fast transient occurs with a rapid change in boundary values, causing pressure waves through the pipe network.

 

 

For this validation case study the transient simulation of the Flownex recuperator element involves the variation of the pressure and temperature boundaries.

 

 



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