PhD Thesis Defence Presentations - Karagiannakis Nikolas

Presentation Title (Τίτλος Παρουσίασης): Simulation οf heat conduction in nanofluids and porous media with meshless techniques
Presentation Type (Τύπος Παρουσίασης): PhD Thesis Defence Presentations
Speakers Full Name (Ονοματεπώνυμο): Karagiannakis Nikolas
Speakers Affiliation (Προέλευση Ομιλητή): Department of Chemical Engineering, University of Patras
Seminar Room (Αίθουσα): "A. C. Payatakes" Library
Event Date: Fri, Nov 27 2020, Time: 16:00 - 19:00
Live webConference Link: https://upatras-gr.zoom.us/j/97193703405?pwd=aFUvNFJYdE5xZ3Y0UFlmRXF2S1Zwdz09
Abstract (Περίληψη)

Many theoretical and experimental studies have shown that the addition of nanoparticles into conventional fluids may generate nanofluids with significantly improved heat transfer properties. Despite the plethora of studies, the mechanisms responsible for the increase of conductivity in nanofluids and their rheological behaviour remain an active research area. At the same time, the study of transport phenomena in complex geometries of porous materials and aggregates is computationally difficult and time consuming. In this work, an innovative numerical method is developed based on meshless techniques, as well as algorithms for the automation of the process of solving heat transfer problems. The model predictions for temperature distribution and effective conductivity are verified by test case problems, other numerical techniques, and experimental data from the literature. A model is developed to describe the natural convection of nanofluids in porous structures, using micropolar flow theory, along with a solution algorithm. It is observed that the addition of nanoparticles reduces the heat transfer under certain conditions. The microstructure of nanofluids and the use of additives to stabilise them seem to be critical factors for the thermal conductivity of nanofluids. A fast and computationally simple technique is developed, for the simulation of aggregate formation with predetermined morphological characteristics in the presence of surfactants. Nanofluids are simulated and the effective thermal conductivity is calculated. Comparisons with experimental data are in good agreement, and it is concluded that the prediction of nanofluid conductivity requires knowledge of the type and amount of surfactant added.

Speakers Short CV (Σύντομο Βιογραφικό Ομιλητή)

EDUCATION 

09/2016-today: PhD candidate, Department of Chemical Engineering, University of Patras.

03/2013–04/2016: MsC in Chemical Engineering, Department of Chemical Engineering, University of Patras, Specialization Diploma in "Simulation, Process optimization and control"

09/2007–09/2012: BSc in Physics, Department of Physics, University of Patras. Specialization Diploma "Theoretical, Computational Physics and Astrophysics"

PUBLICATIONS

  • Karagiannakis, Nikolaos P., Skouras, Eugene D., Burganos, Vasilis N. Modelling “Thermal Conduction in Nanoparticle Aggregates in the Presence of Surfactants”, Nanomaterials, Accepted: 15 November 2020
  • Karagiannakis, Nikolaos P., Bourantas, George C., Skouras, Eugene D., Loukopoulos, Vassilios C., Miller, Karol, Burganos, Vasilis N. “Modeling the Natural Convection Flow in a Square Porous Enclosure Filled with a Micropolar Nanofluid under Magnetohydrodynamic Conditions”, Appl. Sci. 2020, 10(5), 1633; https://doi.org/10.3390/app10051633
  • Karagiannakis, Nikolaos P., Bali, Nadia, Skouras, Eugene D., Burganos, Vasilis N. “An Efficient Meshless Numerical Method for Heat Conduction Studies in Particle Aggregates”, Appl. Sci. 2020, 10(3), 739; https://doi.org/10.3390/app10030739
  • Karagiannakis N.P., Bourantas G.C., Kalarakis A.N., Skouras E.D., Burganos V.N.   “Transient Thermal Conduction with Variable Conductivity using the Meshless Local Petrov-Galerkin Method”, Appl. Math. Comp., 272(2016)676-686

CONFERENCES

  • Ν. Π. Καραγιαννάκης, Ε. Δ. Σκούρας, και Β. Ν. Μπουργανός. “Επίδραση του νανοφλοιού στη θερμική αγωγιμότητα συστάδων νανοσωματιδίων”, 12o Πανελλήνιο Συνέδριο Χημικής Μηχανικής. 2019
  • Ν. Π. Καραγιαννάκης, Ε. Δ. Σκούρας, και Β. Ν. Μπουργανός. “Μοντελοποιηση θερμικής αγωγιμότητας συστάδων νανοσωματιδίων”,11o Πανελλήνιο Συνέδριο Χημικής Μηχανικής. 2017
  • Ν. Π. Καραγιαννάκης, Γ .Μπουραντάς, Α. Ν. Καλαράκης, Ε. Δ. Σκούρας και Β. Ν. Μπουργανός, “Υβριδική Μέθοδος Υπολογισμού Αγωγής και Συναγωγής Θερμότητας με Χρονοχωρικά Μεταβαλλόμενη Αγωγιμότητα χρησιμοποιώντας Καινοτόμες Απλεγματικές Μεθόδους και Μεθόδους Δικτύου-Boltzmann.”, 10o Πανελλήνιο Συνέδριο Χημικής Μηχανικής, Πάτρα 2015.
  • Nikolaos P. Karagiannakis, G. C. Bourantas, Alexandros N. Kalarakis, Eugene D Skouras, Vasilis N. Burganos . “Meshless local Petrov-Galerkin method with moving least squares approximation for transient thermal conduction applications with variable conductivity”.  AIP Conference Proceedings, 1648:art. no. 030009. International Conference of Numerical Analysis and Applied Mathematics, Ρόδος 2015
  • Nikolaos P. Karagiannakis, G. C. Bourantas, Alexandros N. Kalarakis, Eugene D Skouras, Vasilis N. Burganos. “Efficiency of the meshless local Petrov-Galerkin method with moving least squares approximation for thermal conduction applications”. AIP Conference Proceedings, 1558: 2269-2272 (2013). International Conference of Numerical Analysis and Applied Mathematics, Ρόδος 2013

AWARDS/SCHOLARSHIPS

  • PhD candidate scholarshipFORTH/ICE-HT, 2020-today
  • Scholarship of the Hellenic Foundation for Research and Innovation (HFRI), 2017-2020.
  • PhD candidate scholarship FORTH/ICE-HT, 2016-2017.
  • Academic excelence award, Limmat foundation, 2015.
  • Postgraduate Scholarship FORTH/ICE-HT, 2013-2015.
  • Undergraduate Scholarship FORTH/ICE-HT, 2012.