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Dr Ioannis Karathanasis

Senior Lecturer

School of Mathematics, Computer Science and Engineering Department of Mechanical Engineering and Aeronautics

Contact details

Address

Dr Ioannis Karathanasis City, University of London
Northampton Square
London EC1V 0HB
United Kingdom

About

Overview

Dr Ioannis Karathanassis received his PhD from the National Technical University of Athens in 2015 specializing in heat-transfer enhancement techniques and design of cooling devices. His PhD dissertation has been awarded as the best in applied sciences for the year 2015 by NCSR “Demokritos”, the largest research centre of Greece. In the time period 2009-2015, he was also a Research Associate of the Solar & other Energy Systems Laboratory of NCSR Demokritos, where he designed experiments for the evaluation of various renewable-energy applications. Since June 2015, he is working as a Marie Curie/Research Fellow at City, University of London where his research interests comprise modelling of cavitating and boiling flows in injector orifices, as well as experimental measurements and visualization of highly-transient cavitating flows. Dr Karathanassis has a deep understanding of flow-separation mechanisms and mass-transfer processes. From an experimental point of view, he is highly experienced in the development of experimental procedures suitable for the characterization of complex flows.

Qualifications

  1. PhD in Mechanical Engineering, National Technical University of Athens, Athens, Greece, Apr 2015
  2. Master’s Degree in Mechanical Engineering, National Technical University of Athens, Athens, Greece, May 2009

Employment

  1. Lecturer in Mechanical Engineering, School of Mathematics, Computer Science and Engineering, Jan 2018 – present
  2. Research Fellow, School of Mathematics, Computer Science and Engineering, Jun 2016 – Dec 2017
  3. Experienced Marie-Curie Researcher, School of Mathematics, Computer Science and Engineering, Jun 2015 – May 2016
  4. Research Associate, National Center for Scientific Research "Demokritos", Feb 2009 – Apr 2015

Fellowships

  1. Scholarship for doctoral studies, Special Account for Research of the National Technical University of Athens, Jun 2011 – Apr 2015

Memberships of professional organisations

  1. Member, Society of Automotive Engineers, Apr 2016 – present
  2. Member, Technical Chamber of Greece, Oct 2010 – present

Award

  1. National Center for Scientific Research "Demokritos", Athens, Greece (2016) Best PhD Dissertation in Applied Sciences

Research

Dr Karathanassis is currently working on compressible multiphase flows with phase-change and non-idealised fluid properties. More specifically, his research focuses on the study of cavitation formation and induced erosion in practical applications with reference to the automotive and energy industries, such as high-pressure fuel injection and auxiliary equipment, e.g. fuel pumps and hydraulic fittings. In terms of numerical modelling, he is familiar with several methodologies suitable for the prediction of phase change rate in two phase flows including detailed equilibrium, bubble dynamics and semi-empirical models, e.g. the Homogeneous Relaxation Model and formulations based on the kinetic theory of gases, extending to other phase-change regimes, apart from cavitation, such as flash boiling. The numerical models he has developed have been implemented in commercial CFD software, as well as in-house codes and have been passed on to industrial partners (Perkins Engines UK, Caterpillar Fuel Systems) for the prediction of cavitation in Diesel injectors and high-pressure piston pumps.

In reference to experimental activities, Dr Karathanassis's research activities include high-speed, shadowgraphy visualisation studies of in-nozzle cavitating flows for various types of mineral and additised Diesel fuels, as well as high-speed, X-ray phase-contrast and absorption imaging The main focus of his research is to quantify, in terms of vapour generation, and elucidate the topology and dynamics of the transient features of cavitating flow, which are possible to emerge and have a considerable impact on different hydrodynamic machines and other devices, such as ship propellers, turbomachinery blades, high-pressure pumps and fuel injectors. In the course of his appointment at City, he has collaborated closely with a large number of engineers and researchers from partners of various projects, including the Argonne National Laboratory, Caterpillar Fuel Systems (USA), Perkins Engines UK, Lubrizol Ltd. UK, the University of Bergamo (Italy) and TU Delft (Netherlands).

Besides, owing to his doctoral studies, Dr Karathanassis has significant experience in the implementation of novel techniques and the design of devices suitable for the cooling of high-flux heat sources. He has investigated various heat-transfer enhancement techniques, i.e. jet-impingement, linear vortex generators, stacked microchannels, serpentine tubes, dendritic configurations and metal foams. Furthermore, hes has formulated non-deterministic optimisation algorithms to dermine the optimal geometrical layout of heat-sink devices that have been designed, manufactured and their performance has been experimentally evaluated using purpose-specific test rigs developed.

Publications

Publications by category

Chapter

  1. Karathanassis, I.K., Koukouvinis, F.P. and Gavaises, M. (2020). Multiphase Phenomena in Diesel Fuel Injection Systems. Energy, Environment, and Sustainability (pp. 95–126). Springer Singapore.

Conference papers and proceedings (8)

  1. Kyriazis, N., Koukouvinis, P., Karathanassis, I. and Gavaises, M. (2020). A tabulated data technique for cryogenic two-phase flows.
  2. Jadidbonab, H., Karathanassis, I. and Gavaises, E. (2018). Diesel fuel droplet impingement on heated surfaces. Proc. 27th Proceedings of the DIPSI workshop, Droplet Impact Phenomena & Spray Investigations 18-20 May, Bergamo, Italy.
  3. Murali-Girija, M., Koukouvinis, F., Karathanassis, I. and Gavaises, M. (2018). Simulating the effect of in-nozzle cavitation on liquid atomisation using a three-phase model. 10TH INTERNATIONAL SYMPOSIUM ON CAVITATION 14-16 May, Baltimore, USA.
  4. Karathanassis, I., Koukouvinis, P., Lorenzi, M., Kontolatis, E., Li, Z., Wang, J. … Gavaises, M. (2017). High-speed X-Ray Phase Contrast Imaging of String Cavitation in a Diesel Injector Orifice. ILASS2017 - 28th European Conference on Liquid Atomization and Spray Systems 6-8 September.
  5. Karathanasis, I., Koukouvinis, P. and Gavaises, M. (2016). Modelling of flash boiling in nozzle flows. 27th European Conference on Liquid Atomization and Spray Systems Brighton, UK.
  6. Karathanasis, I., Koukouvinis, P. and Gavaises, M. (2016). Simulation of a high pressure fuel pump, including cavitation effects with two multiphase models. 9th International Conference on Multiphase Flow.
  7. Jadidbonab, H., Karathanassis, I., Mitroglou, N. and Gavaises, E. (2016). Diesel Fuel Drop Impingement on a Heated Surface at Elevated Pressure.
  8. Karathanasis, I., Papanikolaou, E., Belessiotis, V. and Bergeles, G.C. (2011). Design and optimization of a micro heat sink for Concentrating Photovoltaic/Thermal systems. 3rd International Micro and Nano Flows Conference Thessaloniki, Greece.

Journal articles (25)

  1. Lyras, T., Karathanassis, I.K., Kyriazis, N., Koukouvinis, P. and Gavaises, M. (2021). Modelling of liquid oxygen nozzle flows under subcritical and supercritical pressure conditions. International Journal of Heat and Mass Transfer, 177, pp. 121559–121559. doi:10.1016/j.ijheatmasstransfer.2021.121559.
  2. Hwang, J., Lee, P., Mun, S., Karathanassis, I.K., Koukouvinis, P., Pickett, L.M. … Gavaises, M. (2021). Machine-learning enabled prediction of 3D spray under engine combustion network spray G conditions. Fuel, 293, pp. 120444–120444. doi:10.1016/j.fuel.2021.120444.
  3. Koukouvinis, P., Rodriguez, C., Hwang, J., Karathanassis, I., Gavaises, M. and Pickett, L. (2021). Machine Learning and transcritical sprays: A demonstration study of their potential in ECN Spray-A. International Journal of Engine Research pp. 146808742110202–146808742110202. doi:10.1177/14680874211020292.
  4. Karathanassis, I.K., Heidari-Koochi, M., Zhang, Q., Hwang, J., Koukouvinis, P., Wang, J. … Gavaises, M. (2021). X-ray phase contrast and absorption imaging for the quantification of transient cavitation in high-speed nozzle flows. Physics of Fluids, 33(3), pp. 32102–32102. doi:10.1063/5.0038475.
  5. Karathanassis, I.K., Hwang, J., Koukouvinis, P., Pickett, L. and Gavaises, M. (2021). Combined visualisation of cavitation and vortical structures in a real-size optical diesel injector. Experiments in Fluids, 62(1). doi:10.1007/s00348-020-03096-1.
  6. Hwang, J., Weiss, L., Karathanassis, I.K., Koukouvinis, P., Pickett, L.M. and Skeen, S.A. (2020). Spatio-temporal identification of plume dynamics by 3D computed tomography using engine combustion network spray G injector and various fuels. Fuel, 280, pp. 118359–118359. doi:10.1016/j.fuel.2020.118359.
  7. Brunhart, M., Soteriou, C., Gavaises, M., Karathanassis, I., Koukouvinis, P., Jahangir, S. … Poelma, C. (2020). Investigation of cavitation and vapor shedding mechanisms in a Venturi nozzle. Physics of Fluids, 32(8), pp. 83306–83306. doi:10.1063/5.0015487.
  8. Karathanassis, I.K., Pashkovski, E., Heidari-Koochi, M., Jadidbonab, H., Smith, T., Gavaises, M. … Bruecker, C. (2020). Non-Newtonian flow of highly-viscous oils in hydraulic components. Journal of Non-Newtonian Fluid Mechanics pp. 1–1. doi:10.1016/j.jnnfm.2019.104221.
  9. Mithun, M.-.G., Koukouvinis, P., Karathanassis, I.K. and Gavaises, M. (2019). Numerical simulation of three-phase flow in an external gear pump using immersed boundary approach. Applied Mathematical Modelling, 72, pp. 682–699. doi:10.1016/j.apm.2019.03.022.
  10. Karathanassis, I.K., Papanicolaou, E., Belessiotis, V. and Bergeles, G.C. (2019). Dynamic simulation and exergetic optimization of a Concentrating Photovoltaic/ Thermal (CPVT) system. Renewable Energy, 135, pp. 1035–1047. doi:10.1016/j.renene.2018.12.085.
  11. Naseri, H., Trickett, K., Mitroglou, N., Karathanassis, I., Koukouvinis, P., Gavaises, M. … Wang, J. (2018). Turbulence and Cavitation Suppression by Quaternary Ammonium Salt Additives. Scientific Reports, 8(1). doi:10.1038/s41598-018-25980-x.
  12. Karathanassis, I.K., Trickett, K., Koukouvinis, P., Wang, J., Barbour, R. and Gavaises, M. (2018). Illustrating the effect of viscoelastic additives on cavitation and turbulence with X-ray imaging. Scientific Reports, 8(1). doi:10.1038/s41598-018-32996-w.
  13. Jadidbonab, H., Malgarinos, I., Karathanassis, I., Mitroglou, N. and Gavaises, M. (2018). We-T classification of diesel fuel droplet impact regimes. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 474(2215). doi:10.1098/rspa.2017.0759.
  14. Karathanassis, I.K., Koukouvinis, P., Kontolatis, E., Lee, Z., Wang, J., Mitroglou, N. … Gavaises, M. (2018). High-speed visualization of vortical cavitation using synchrotron radiation. Journal of Fluid Mechanics, 838, pp. 148–164. doi:10.1017/jfm.2017.885.
  15. Koukouvinis, P., Karathanassis, I.K. and Gavaises, M. (2018). Prediction of cavitation and induced erosion inside a high-pressure fuel pump. International Journal of Engine Research, 19(3), pp. 360–373. doi:10.1177/1468087417708137.
  16. Jadidbonab, H., Mitroglou, N., Karathanassis, I. and Gavaises, M. (2018). Experimental Study of Diesel-Fuel Droplet Impact on a Similarly Sized Polished Spherical Heated Solid Particle. Langmuir, 34(1), pp. 36–49. doi:10.1021/acs.langmuir.7b01658.
  17. Karathanassis, I.K., Koukouvinis, P. and Gavaises, M. (2017). Comparative evaluation of phase-change mechanisms for the prediction of flashing flows. International Journal of Multiphase Flow, 95, pp. 257–270. doi:10.1016/j.ijmultiphaseflow.2017.06.006.
  18. Mitroglou, N., Stamboliyski, V., Karathanassis, I.K., Nikas, K.S. and Gavaises, M. (2017). Cloud cavitation vortex shedding inside an injector nozzle. Experimental Thermal and Fluid Science, 84, pp. 179–189. doi:10.1016/j.expthermflusci.2017.02.011.
  19. Karathanassis, I.K., Papanicolaou, E., Belessiotis, V. and Bergeles, G.C. (2017). Design and experimental evaluation of a parabolic-trough concentrating photovoltaic/thermal (CPVT) system with high-efficiency cooling. Renewable Energy, 101, pp. 467–483. doi:10.1016/j.renene.2016.09.013.
  20. Karathanassis, I.K., Koukouvinis, P. and Gavaises, M. (2016). TOPOLOGY AND DISTINCT FEATURES OF FLASHING FLOW IN AN INJECTOR NOZZLE. Atomization and Sprays, 26(12), pp. 1307–1336. doi:10.1615/atomizspr.2016016510.
  21. Karathanassis, I.K., Papanicolaou, E., Belessiotis, V. and Bergeles, G.C. (2015). Experimental and numerical evaluation of an elongated plate-fin heat sink with three sections of stepwise varying channel width. International Journal of Heat and Mass Transfer, 84, pp. 16–34. doi:10.1016/j.ijheatmasstransfer.2014.12.013.
  22. Karathanassis, I.K., Papanicolaou, E., Belessiotis, V. and Bergeles, G.C. (2014). Flow and Temperature Fields in Cooling Devices with Embedded Serpentine Tubes. Numerical Heat Transfer, Part A: Applications, 66(4), pp. 349–378. doi:10.1080/10407782.2014.884864.
  23. Karathanassis, I.K., Papanicolaou, E., Belessiotis, V. and Bergeles, G.C. (2013). Multi-objective design optimization of a micro heat sink for Concentrating Photovoltaic/Thermal (CPVT) systems using a genetic algorithm. Applied Thermal Engineering, 59(1-2), pp. 733–744. doi:10.1016/j.applthermaleng.2012.06.034.
  24. Karathanassis, I.K., Papanicolaou, E., Belessiotis, V. and Bergeles, G.C. (2013). Effect of secondary flows due to buoyancy and contraction on heat transfer in a two-section plate-fin heat sink. International Journal of Heat and Mass Transfer, 61, pp. 583–597. doi:10.1016/j.ijheatmasstransfer.2013.02.028.
  25. Karathanassis, I.K., Papanicolaou, E., Belessiotis, V. and Bergeles, G.C. (2013). Three-dimensional flow effects on forced convection heat transfer in a channel with stepwise-varying width. International Journal of Thermal Sciences, 67, pp. 177–191. doi:10.1016/j.ijthermalsci.2012.12.016.

Professional activities

Collaborations (academic) (4)

  1. Researcher of X-ray time-resolved quantification of cavitating flow in Diesel fuel project (Jul 2017 – present)
    Other partners: Argonne National Laboratory
  2. Researcher of Holistic Approach of Spray Injection through a generalized multi-phase framework project (Sep 2016 – present)
    Other partners: EU H2020 ITN-HAoS Project
  3. Researcher of Development and experimental validation of computational models for cavitating flows, surface erosion damage and material loss project (May 2016 – present)
    Sponsored by EU H2020 ITN-CAFE Project
  4. Researcher of Design of durable fuel-injection systems through use of newly developed CFD models able to indicate locations vulnerable to cavitation erosion project (Jun 2015 – May 2016)
    Other partners: EU FP7-FS3000 Project

Keynote lectures/speeches (6)

  1. Optical and x-ray visualization of cavitating injector flows. 14th International Conference on Engines for Vehicles, Lake Toya, Hokkaido, Japan (2017).
  2. X-ray measurements of cavitating vortices in orifices. 5th IICR Workshop, Chania, Greece (2017).
  3. Different modelling approaches for flash boiling. 1st UK Fluids Network, Special Interest Group on Sprays Workshop, University of Brighton, UK (2017).
  4. X-ray phase-contrast measurements and CFD simulations of cavitation in a Diesel nozzle orifice replica. DIPSI Workshop, University of Bergamo, Italy (2017).
  5. Cavitation measurements in Diesel injector flows. Sandia National Laboratories, Livermore, USA (2016).
  6. Cavitation and flash boiling in injector nozzles. Ann Arbor, USA (2016).