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Tesi etd-03252015-164915


Thesis type
Tesi di laurea specialistica
Author
ROSA, DONATO
email address
donato.rosa@outlook.it
URN
etd-03252015-164915
Title
Assessment of the NEK5000 code for Direct Numerical Simulations
Struttura
INGEGNERIA CIVILE E INDUSTRIALE
Corso di studi
INGEGNERIA NUCLEARE E DELLA SICUREZZA INDUSTRIALE
Supervisors
relatore Prof. Ambrosini, Walter
relatore Prof. Forgione, Nicola
relatore Dott. Shams, Afaque
Parole chiave
  • SEM
  • Turbulence
  • Conjugate Heat Transfer
  • DNS
  • NEK5000
  • Turbulent Channel Flow
Data inizio appello
27/04/2015;
Consultabilità
Parziale
Data di rilascio
27/04/2018
Riassunto analitico
The present work is included in the frame of the fundamental studies performed worldwide aiming at improving the prediction tools for investigating turbulence phenomena, in order to provide the basis for the assessment of codes and models suitable for the detailed analysis of complex fluid systems, like nuclear reactors.

A critical aspect of the nuclear reactor safety is the fluid-structure interaction, and in particular, the combined effect of a turbulent flow with a thermal mixing, which may lead to local Thermal Fatigue phenomena into the structures due to Thermal Striping.

The main goal of the present work is to assess the DNS capabilities of the spectral elements code NEK5000 for the fundamental turbulent flows and their thermal interaction with solid structures. This work is divided into two parts.In the first part, DNS computations are carried out in order to evaluate the performances of the code in predicting the turbulent flow behaviour for simplistic channel flow configurations.
Whereas, in the second part, the DNS analyses are further extended for a conjugate heat transfer case, i.e. a planer channel flow along with heated walls. Three different temperature fields are considered.

A wide range of numerical parameters are tested and their influence is studied in order to obtain high quality turbulence statistics both for the velocity and the thermal fields. The obtained results are compared against other well-known DNS databases available in literature. The comparison suggests that NEK5000 exhibits excellent capabilities to perform high quality DNS computations.
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