Researchers at UCD

Lennon Ó'Náraigh


School of Mathematics & Statistics
UCD Institute for Discvoery
Science East

Tel: Ext. 2546


I am an applied mathematician by training, interested in the application of any mathematical tool to any problem of practical interest, especially the difficult ones.




Association: American Physical Society, Function/Role: Member, Division of Fluid Dynamics


Year 2005 Institution: Trinity College Dublin
Qualification: BA Subject:
Year 2008 Institution: Imperial College, London, UK
Qualification: PhD Subject:

Journals Edited

Physics Of Fluids: Reviewer.
Physical Review. E, Statistical, Nonlinear, And Soft Matter Physics: Reviewer.



Book Chapters

Lennon O'Naraigh and Prashant Valluri (2017) 'Stability Analysis and Drect Numerical Simulation for Two-Phase Flows and Heat Transfer: A Complementary Approach' In: John R Thome (eds). Encyclopedia of Two-Phase Heat Transfer and Flow III. Singapore: World Scientific Press. [Details]

Peer Reviewed Journals

Zlatko Solomenko, Peter D.M. Spelt, Lennon O'Naraigh, Pascal Alix (2017) 'Mass conservation and reduction of parasitic interfacial waves in level-set methods for the numerical simulation of two-phase flows: a comparative study'. International Journal of Multiphase Flow, 95 :235-256. [DOI] [Details]
Lennon O'Naraigh (2017) 'Advection of nematic liquid crystals by chaotic flow'. Physics of Fluids, . [DOI] [Details]
Patrick Schmidt, Lennon O'Naraigh, Mathieu Lucquiaud, and Prashant Valluri (2016) 'Linear and nonlinear instability in vertical counter-current laminar gas-liquid flows'. Physics of Fluids, 28 :042102. [DOI] [Details]
Lennon O'Naraigh and Ricardo Barros (2016) 'Particle-laden viscous channel flows: model regularization and parameter study'. European Journal of Mechanics, B/Fluids, . [DOI] [Details]
James Fannon, Iain Bethune, Prashant Valluri, Jean-Christophe Loiseau, and Lennon O'Naraigh (2016) 'High-performance computational fluid dynamics: a custom-code approach'. European Journal of Physics, 37 :045001. [DOI] [Details]
Lennon O'Naraigh, Selma Shun, and Aurore Naso (2015) 'Flow-parametric regulation of shear-driven phase separation in two and three dimensions'. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 91 :062127. [DOI] [Details]
Lennon O'Naraigh (2015) 'Global modes in nonlinear non-normal evolutionary models: exact solutions, perturbation theory, direct numerical simulation, and chaos'. Physica D: Nonlinear Phenomena, 309 :20. [DOI] [Details]
Lennon O'Naraigh, Prashant Valluri, David Scott, Iain Bethune, and Peter D. M. Spelt (2014) 'Linear instability, nonlinear instability, and ligament dynamics in three-dimensional laminar two-layer liquid/liquid flows'. Journal of Fluid Mechanics, . [DOI] [Details]
Lennon O'Naraigh and Peter D. M. Spelt (2013) 'An analytical connection between temporal and spatio-temporal growth rates in linear stability analysis'. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 469 :20130171. [DOI] [Details]
Lennon Ó Náraigh, Peter D. M. Spelt, Stephn J. Shaw (2013) 'Absolute linear instability in laminar and turbulent gas/liquid two-layer channel flow'. Journal of Fluid Mechanics, . [DOI] [Details]
Lennon Ó Náraigh and Doireann O'Kiely (2012) 'Homogenization theory for periodic potentials in the Schroedinger Equation'. European Journal of Physics, . [DOI] [Details]
Lennon O'Naraigh, Khalid Kamhawi (2011) 'Multiscale methods and modelling for chemical reactions on oscillating surfaces'. IMA Journal of Applied Mathematics, . [DOI] [Details]
Lennon Ó Náraigh, Peter Spelt, Omar Matar, Tamer Zaki; (2011) 'Interfacial instability in turbulent flow over a liquid film in a channel'. International Journal Of Multiphase Flow, . [DOI] [Details]
Lennon Ó Naraigh, Peter Spelt, Tamer Zaki; (2011) 'Turbulent flow over a liquid layer rvisited: multi-equation turbulent modelling'. Journal of Fluid Mechanics, . [DOI] [Details]
Lennon Ó Náraigh; (2010) 'Modelling the growth rate of a tracer gradient using stochastic differential equations'. European Journal of Mechanics, B/Fluids, . [DOI] [Details]
Prashant Valluri, Lennon Ó Náraigh, Hang Ding, Peter D. M. Spelt; (2010) 'Linear and nonlinear spatio-temporal instability in laminar two-layer flows'. Journal of Fluid Mechanics, . [DOI] [Details]
Naraigh, LO,Spelt, PDM; (2010) 'Interfacial instability of turbulent two-phase stratified flow: Pressure-driven flow and non-Newtonian layers'. Journal of non-newtonian fluid mechanics, 165 :489-508. [DOI] [Details]
Lennon Ó Náraigh and Jean-Luc Thiffeault; (2010) 'Nonlinear dynamics of phase separation in thin films'. Nonlinearity, 23 :1559. [DOI] [Details]
Darryl D. Holm, Lennon Ó Náraigh, and Cesare Tronci; (2009) 'Singular solutions of a modified two-component Camassa-Holm equation'. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, . [DOI] [Details]
Darryl D. Holm, Lennon Ó Náraigh, and Cesare Tronci; (2008) 'Emergent singular solutions of nonlocal density-magnetization equations in one dimension'. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, . [DOI] [Details]
Lennon Ó Náraigh and Jean-Luc Thiffeault; (2008) 'Bounds on the mixing enhancement for a stirred binary fluid'. Physica D: Nonlinear Phenomena, . [DOI] [Details]
Lennon Ó Náraigh and Jean-Luc Thiffeault; (2007) 'Bubbles and filaments: Stirring a Cahn-Hilliard fluid'. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, . [DOI] [Details]
Lennon Ó Náraigh and Jean-Luc Thiffeault; (2007) 'Dynamical effects and phase separation in cooled binary fluid films'. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, . [DOI] [Details]

Conference Publications

Lennon O'Naraigh, Iain Bethune, David Scott, Zlatko Solomenko, Peter Spelt, Prashant Valluri (2017) Direct numerical simulation of interfacial instability in gas-liquid flows Parallel Computational Fluid Dynamics [Details]
I. Bethune, T. Collis, L. O'Naraigh, D. Scott, and P. Valluri (2015) Developing a scalable and flexible high-resolution DNS code for two-phase flows International Conference on Parallel Computing (ParCo) [DOI] [Details]
Zadrazil, I., Christos N. Markides, Omar K. Matar, L. O. Naraigh, and Geoffrey F. Hewitt (2012) Characterisation of downwards co-current gas-liquid annular flows Seventh International Symposium On Turbulence, Heat and Mass Transfer Palermo [DOI] [Details]
L. O'Naraigh, O.K. Matar, P.D. M. Spelt, T.A. Zaki (2008) Interfacial stability in turbulent pressure-driven channel flow AIChE Annual Meeting, Conference Proceedings [Details]

Published Reports

Lennon Ó Náraigh and Prashant Valluri; (2011) Towards a complete description of two-phase interfacial dynamics in turbulent stratified flow. European Commission, Brussels. [Details]


Research Interests

My research falls under three areas:

  1. Interfacial instability of two-phase stratified flows;
  2. Turbulence in two dimensions with reference to mixing;
  3. Applications of the Cahn-Hilliard equation

Topic 1 inovles linear-stability analyses to describe absolute and convective instabilities in Reynolds-averaged stratified flow systems.  Topic 2 involves the modelling and simulation of turbulence in two dimensions, including the application of stochstic methods.  Topic 3 is a very diverse area and in the past, has involved chaotic mixing and lubrication theory.

Research Projects

Sponsor : Irish Research Council for Science Engineering and Technology (IRCSET)
Title : Towards a complete numerical description of two-phase turbulence
Start Date / End Date : 01-JUL-12 / 30-NOV-13



External Collaborators

  1. I collaborate with Jean-Luc Thiffeault on problems involving mixing and the Cahn-Hilliard equation.  Prof. Thiffeault is based at the University of Wisconsin, Madison, USA
  2. I collaborate with Darryl Holm on any numerical problem of mutual interest.  Prof. Holm is based at Imperial College London, UK.
  3. I collaborate with Peter Spelt on interfacial turbulence.  Dr. Spelt is based at Imperial College London, UK.
  4. I collaborate with Prashant Valluri on interfacial turbulence, in particular, linear stability analyses.  Dr. Valluri is based at the University of Edinburgh, UK.