Address

Chair of Computational Science
Clausiusstrasse 33
ETH-Zentrum, CLT B 11
CH-8092 Zürich

Contact Information

Call: +41 44 632 2645

Email:

Jens Honore Walther

Research Associate

Research

Education

PhD in Mechanical Engineering, Technical University of Denmark, 1994

Selected Publications

2018

  • N. Karvounis, K. M. Pang, S. Mayer, and J. H. Walther, “Numerical simulation of condensation of sulfuric acid and water in a large two-stroke marine diesel engine,” Appl. Energ., vol. 211, p. 1009–1020, 2018.
    [BibTeX] [PDF] [DOI]
    @Article{karvounis2018a,
    author = {Nikolas Karvounis and Kar Mun Pang and Stefan Mayer and Jens Honor{\'{e}} Walther},
    journal = {{Appl. Energ.}},
    title = {Numerical simulation of condensation of sulfuric acid and water in a large two-stroke marine diesel engine},
    year = {2018},
    month = {feb},
    pages = {1009--1020},
    volume = {211},
    doi = {10.1016/j.apenergy.2017.11.085},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/karvounis2018a.pdf},
    }

  • J. C. Ong, K. M. Pang, J. H. Walther, J. Ho, and H. K. Ng, “Evaluation of a lagrangian soot tracking method for the prediction of primary soot particle size under engine-like conditions,” J. Aerosol Sci., vol. 115, p. 70–95, 2018.
    [BibTeX] [PDF] [DOI]
    @Article{ong2018a,
    author = {Jiun Cai Ong and Kar Mun Pang and Jens Honore Walther and Jee-Hou Ho and Hoon Kiat Ng},
    journal = {{J. Aerosol Sci.}},
    title = {Evaluation of a Lagrangian Soot Tracking Method for the prediction of primary soot particle size under engine-like conditions},
    year = {2018},
    month = {jan},
    pages = {70--95},
    volume = {115},
    doi = {10.1016/j.jaerosci.2017.10.013},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/ong2018a.pdf},
    }

  • H. J. Spietz, M. M. Hejlesen, and J. H. Walther, “A regularization method for solving the Poisson equation for mixed unbounded-periodic domains,” J. Comput. Phys., vol. 356, p. 439–447, 2018.
    [BibTeX] [PDF] [DOI]
    @Article{spietz2018a,
    author = {Henrik Juul Spietz and Mads M{\o}lholm Hejlesen and Jens Honor{\'{e}} Walther},
    journal = {{J. Comput. Phys.}},
    title = {A regularization method for solving the {P}oisson equation for mixed unbounded-periodic domains},
    year = {2018},
    month = {mar},
    pages = {439--447},
    volume = {356},
    doi = {10.1016/j.jcp.2017.12.018},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/spietz2018a.pdf},
    }

  • M. L. Szanyi, C. S. Hemmingsen, W. Yan, J. H. Walther, and S. L. Glimberg, “Near-wellbore modeling of a horizontal well with computational fluid dynamics,” J. Petrol. Sci. Eng., vol. 160, p. 119–128, 2018.
    [BibTeX] [PDF] [DOI]
    @Article{szanyi2018a,
    author = {M{\'{a}}rton L. Szanyi and Casper S. Hemmingsen and Wei Yan and Jens H. Walther and Stefan L. Glimberg},
    journal = {{J. Petrol. Sci. Eng.}},
    title = {Near-wellbore modeling of a horizontal well with Computational Fluid Dynamics},
    year = {2018},
    month = {jan},
    pages = {119--128},
    volume = {160},
    doi = {10.1016/j.petrol.2017.10.011},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/szanyi2018a.pdf},
    }

2017

  • E. R. Cruz-Chú, E. Papadopoulou, J. H. Walther, A. Popadić, G. Li, M. Praprotnik, and P. Koumoutsakos, “On phonons and water flow enhancement in carbon nanotubes,” Nat. Nanotechnol., vol. 12, iss. 12, p. 1106–1108, 2017.
    [BibTeX] [PDF] [DOI]
    @article{cruzchu2017a,
    author = {Eduardo R. Cruz-Ch{\'{u}} and Ermioni Papadopoulou and Jens H. Walther and Aleksandar Popadi{\'{c}} and Gengyun Li and Matej Praprotnik and Petros Koumoutsakos},
    doi = {10.1038/nnano.2017.234},
    journal = {{Nat. Nanotechnol.}},
    month = {dec},
    number = {12},
    pages = {1106--1108},
    publisher = {Springer Nature},
    title = {On phonons and water flow enhancement in carbon nanotubes},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/cruzchu2017a.pdf},
    volume = {12},
    year = {2017}
    }

  • A. Andersen, T. Bohr, T. Schnipper, and J. H. Walther, “Wake structure and thrust generation of a flapping foil in two-dimensional flow,” J. Fluid Mech., vol. 812, 2017.
    [BibTeX] [PDF] [DOI]
    @Article{andersen2017a,
    author = {A. Andersen and T. Bohr and T. Schnipper and J. H. Walther},
    journal = {{J. Fluid Mech.}},
    title = {Wake structure and thrust generation of a flapping foil in two-dimensional flow},
    year = {2017},
    month = {dec},
    volume = {812},
    doi = {10.1017/jfm.2016.808},
    publisher = {Cambridge University Press ({CUP})},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/andersen2017a.pdf},
    }

  • I. Hanasaki and J. H. Walther, “Suspended particle transport through constriction channel with Brownian motion,” Phys. Rev. E, vol. 96, iss. 2, 2017.
    [BibTeX] [PDF] [DOI]
    @Article{hanasaki2017a,
    author = {Itsuo Hanasaki and Jens H. Walther},
    journal = {{Phys. Rev. E}},
    title = {Suspended particle transport through constriction channel with {B}rownian motion},
    year = {2017},
    month = {aug},
    number = {2},
    volume = {96},
    doi = {10.1103/physreve.96.023109},
    publisher = {American Physical Society ({APS})},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/hanasaki2017a.pdf},
    }

  • L. T. Nielsen, S. S. Asadzadeh, J. Dölger, J. H. Walther, T. Kiørboe, and A. Andersen, “Hydrodynamics of microbial filter feeding,” P. Natl. A. Sci., vol. 114, iss. 35, p. 9373–9378, 2017.
    [BibTeX] [PDF] [DOI]
    @Article{nielsen2017a,
    author = {Nielsen, Lasse Tor and Asadzadeh, Seyed Saeed and D{\"o}lger, Julia and Walther, Jens H. and Ki{\o}rboe, Thomas and Andersen, Anders},
    journal = {{P. Natl. A. Sci.}},
    title = {Hydrodynamics of microbial filter feeding},
    year = {2017},
    month = {aug},
    number = {35},
    pages = {9373--9378},
    volume = {114},
    doi = {10.1073/pnas.1708873114},
    publisher = {Proceedings of the National Academy of Sciences},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/nielsen2017a.pdf},
    }

  • K. M. Pang, N. Karvounis, J. H. Walther, J. Schramm, P. Glarborg, and S. Mayer, “Modelling of temporal and spatial evolution of sulphur oxides and sulphuric acid under large, two-stroke marine engine-like conditions using integrated CFD-chemical kinetics,” Appl. Energ., vol. 193, p. 60–73, 2017.
    [BibTeX] [PDF] [DOI]
    @Article{pang2017a,
    author = {Kar Mun Pang and Nikolas Karvounis and Jens Honore Walther and Jesper Schramm and Peter Glarborg and Stefan Mayer},
    journal = {{Appl. Energ.}},
    title = {Modelling of temporal and spatial evolution of sulphur oxides and sulphuric acid under large, two-stroke marine engine-like conditions using integrated {CFD}-chemical kinetics},
    year = {2017},
    month = {may},
    pages = {60--73},
    volume = {193},
    doi = {10.1016/j.apenergy.2017.02.020},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/pang2017a.pdf},
    }

  • N. Ramos-García, M. M. Hejlesen, J. N. Sørensen, and J. H. Walther, “Hybrid vortex simulations of wind turbines using a three-dimensional viscous-inviscid panel method,” Wind Energy, vol. 20, iss. 11, p. 1871–1889, 2017.
    [BibTeX] [PDF] [DOI]
    @Article{ramosgarcia2017a,
    author = {N{\'{e}}stor Ramos-Garc{\'{\i}}a and Mads M{\o}lholm Hejlesen and Jens N{\o}rkaer S{\o}rensen and Jens Honor{\'{e}} Walther},
    journal = {{Wind Energy}},
    title = {Hybrid vortex simulations of wind turbines using a three-dimensional viscous-inviscid panel method},
    year = {2017},
    month = {jun},
    number = {11},
    pages = {1871--1889},
    volume = {20},
    doi = {10.1002/we.2126},
    publisher = {Wiley-Blackwell},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/ramosgarcia2017a.pdf},
    }

  • H. J. Spietz, M. M. Hejlesen, and J. H. Walther, “Iterative Brinkman penalization for simulation of impulsively started flow past a sphere and a circular disc,” J. Comput. Phys., vol. 336, p. 261–274, 2017.
    [BibTeX] [PDF] [DOI]
    @Article{spietz2017a,
    author = {Spietz, Henrik Juul and Hejlesen, Mads M{\o}lholm and Walther, Jens Honor{\'{e}}},
    journal = {{J. Comput. Phys.}},
    title = {Iterative {B}rinkman penalization for simulation of impulsively started flow past a sphere and a circular disc},
    year = {2017},
    month = {may},
    pages = {261--274},
    volume = {336},
    doi = {10.1016/j.jcp.2017.01.064},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/spietz2017a.pdf},
    }

2016

  • J. Chen, J. H. Walther, and P. Koumoutsakos, “Ultrafast cooling by covalently bonded graphene-carbon nanotube hybrid immersed in water,” Nanotechnology, vol. 27, iss. 46, p. 465705, 2016.
    [BibTeX] [PDF] [DOI]
    @article{chen2016a,
    author = {Jie Chen and Jens H Walther and Petros Koumoutsakos},
    doi = {10.1088/0957-4484/27/46/465705},
    journal = {Nanotechnology},
    month = {oct},
    number = {46},
    pages = {465705},
    publisher = {{IOP} Publishing},
    title = {Ultrafast cooling by covalently bonded graphene-carbon nanotube hybrid immersed in water},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/chen2016a.pdf},
    volume = {27},
    year = {2016}
    }

  • B. O. Andersen, N. F. Nielsen, and J. H. Walther, “Numerical and experimental study of pulse-jet cleaning in fabric filters,” Powder Technol., vol. 291, p. 284–298, 2016.
    [BibTeX] [PDF] [DOI]
    @Article{andersen2016a,
    author = {B.O. Andersen and N.F. Nielsen and J.H. Walther},
    journal = {{Powder Technol.}},
    title = {Numerical and experimental study of pulse-jet cleaning in fabric filters},
    year = {2016},
    month = {apr},
    pages = {284--298},
    volume = {291},
    doi = {10.1016/j.powtec.2015.12.028},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/andersen2016a.pdf},
    }

  • C. S. Hemmingsen, K. M. Ingvorsen, S. Mayer, and J. H. Walther, “LES and URANS simulations of the swirling flow in a dynamic model of a uniflow-scavenged cylinder,” Int. J. Heat Fluid Fl., vol. 62, p. 213–223, 2016.
    [BibTeX] [PDF] [DOI]
    @Article{hemmingsen2016a,
    author = {Casper S. Hemmingsen and Kristian M. Ingvorsen and Stefan Mayer and Jens H. Walther},
    journal = {{Int. J. Heat Fluid Fl.}},
    title = {{LES} And {URANS} simulations of the swirling flow in a dynamic model of a uniflow-scavenged cylinder},
    year = {2016},
    month = {dec},
    pages = {213--223},
    volume = {62},
    doi = {10.1016/j.ijheatfluidflow.2016.10.008},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/hemmingsen2016a.pdf},
    }

  • N. K. Karna, E. Oyarzua, J. H. Walther, and H. A. Zambrano, “Effect of the meniscus contact angle during early regimes of spontaneous imbibition in nanochannels,” Phys. chem. chem. phys., vol. 18, iss. 47, p. 31997–32001, 2016.
    [BibTeX] [PDF] [DOI]
    @article{karna2016a,
    author = {Nabin Kumar Karna and Elton Oyarzua and Jens H. Walther and Harvey A. Zambrano},
    doi = {10.1039/c6cp06155a},
    journal = {Phys. Chem. Chem. Phys.},
    number = {47},
    pages = {31997--32001},
    publisher = {Royal Society of Chemistry ({RSC})},
    title = {Effect of the meniscus contact angle during early regimes of spontaneous imbibition in nanochannels},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/karna2016a.pdf},
    volume = {18},
    year = {2016}
    }

  • K. M. Pang, N. Karvounis, J. H. Walther, and J. Schramm, “Numerical investigation of soot formation and oxidation processes under large two-stroke marine diesel engine-like conditions using integrated CFD-chemical kinetics,” Appl. Energ., vol. 169, p. 874–887, 2016.
    [BibTeX] [PDF] [DOI]
    @Article{pang2016a,
    author = {Kar Mun Pang and Nikolas Karvounis and Jens Honore Walther and Jesper Schramm},
    journal = {{Appl. Energ.}},
    title = {Numerical investigation of soot formation and oxidation processes under large two-stroke marine diesel engine-like conditions using integrated {CFD}-chemical kinetics},
    year = {2016},
    month = {may},
    pages = {874--887},
    volume = {169},
    doi = {10.1016/j.apenergy.2016.02.081},
    publisher = {Elsevier {BV}},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/pang2016a.pdf},
    }

2015

  • D. Alexeev, J. Chen, J. H. Walther, K. P. Giapis, P. Angelikopoulos, and P. Koumoutsakos, “Kapitza resistance between few-layer graphene and water: liquid layering effects,” Nano Lett., vol. 15, iss. 9, p. 5744–5749, 2015.
    [BibTeX] [Abstract] [Supplemental] [PDF] [DOI]

    The Kapitza resistance (R_K) between few-layer graphene (FLG) and water was studied using molecular dynamics simulations. The R_K was found to depend on the number of the layers in the FLG though, surprisingly, not on the water block thickness. This distinct size dependence is attributed to the large difference in the phonon mean free path between the FLG and water. Remarkably, R_K is strongly dependent on the layering of water adjacent to the FLG, exhibiting an inverse proportionality relationship to the peak density of the first water layer, which is consistent with better acoustic phonon matching between FLG and water. These findings suggest novel ways to engineer the thermal transport properties of solid{–}liquid interfaces by controlling and regulating the liquid layering at the interface.

    @article{alexeev2015a,
    author = {Dmitry Alexeev and Jie Chen and Jens H. Walther and Konstantinos P. Giapis and Panagiotis Angelikopoulos and Petros Koumoutsakos},
    doi = {10.1021/acs.nanolett.5b03024},
    journal = {{Nano Lett.}},
    month = {sep},
    number = {9},
    pages = {5744--5749},
    publisher = {American Chemical Society ({ACS})},
    supplemental = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/alexeev2015a_supplemental.pdf},
    title = {Kapitza Resistance between Few-Layer Graphene and Water: Liquid Layering Effects},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/alexeev2015a.pdf},
    volume = {15},
    year = {2015}
    }

  • J. Chen, J. H. Walther, and P. Koumoutsakos, “Covalently bonded graphene-carbon nanotube hybrid for high-performance thermal interfaces,” Adv. Funct. Mater., vol. 25, iss. 48, p. 7539–7545, 2015.
    [BibTeX] [Abstract] [PDF] [DOI]

    The remarkable thermal properties of graphene and carbon nanotubes (CNTs) have been the subject of intensive investigations for the thermal management of integrated circuits. However, the small contact area of CNTs and the large anisotropic heat conduction of graphene have hindered their applications as effective thermal interface materials (TIMs). Here, a covalently bonded graphene{–}CNT (G-CNT) hybrid is presented that multiplies the axial heat transfer capability of individual CNTs through their parallel arrangement, while at the same time it provides a large contact area for efficient heat extraction. Through computer simulations, it is demonstrated that the G-CNT outperforms few-layer graphene by more than 2 orders of magnitude for the c-axis heat transfer, while its thermal resistance is 3 orders of magnitude lower than the state-of-the-art TIMs. We show that heat can be removed from the G-CNT by immersing it in a liquid. The heat transfer characteristics of G-CNT suggest that it has the potential to revolutionize the design of high-performance TIMs.

    @article{chen2015a,
    author = {Jie Chen and Jens H. Walther and Petros Koumoutsakos},
    doi = {10.1002/adfm.201501593},
    journal = {{Adv. Funct. Mater.}},
    month = {nov},
    number = {48},
    pages = {7539--7545},
    publisher = {Wiley-Blackwell},
    title = {Covalently Bonded Graphene-Carbon Nanotube Hybrid for High-Performance Thermal Interfaces},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/chen2015a.pdf},
    volume = {25},
    year = {2015}
    }

  • M. M. Hejlesen, P. Koumoutsakos, A. Leonard, and J. H. Walther, “Iterative Brinkman penalization for remeshed vortex methods,” J. Comput. Phys., vol. 280, p. 547–562, 2015.
    [BibTeX] [Abstract] [PDF] [DOI]

    We introduce an iterative Brinkman penalization method for the enforcement of the no-slip boundary condition in remeshed vortex methods. In the proposed method, the Brinkman penalization is applied iteratively only in the neighborhood of the body. This allows for using significantly larger time steps, than what is customary in the Brinkman penalization, thus reducing its computational cost while maintaining the capability of the method to handle complex geometries. We demonstrate the accuracy of our method by considering challenging benchmark problems such as flow past an impulsively started cylinder and normal to an impulsively started and accelerated flat plate. We find that the present method enhances significantly the accuracy of the Brinkman penalization technique for the simulations of highly unsteady flows past complex geometries.

    @article{hejlesen2015c,
    author = {Hejlesen, Mads M{\o}lholm and Koumoutsakos, Petros and Leonard, Anthony and Walther, Jens Honor{\'{e}}},
    doi = {10.1016/j.jcp.2014.09.029},
    journal = {{J. Comput. Phys.}},
    month = {jan},
    pages = {547--562},
    publisher = {Elsevier {BV}},
    title = {Iterative {B}rinkman penalization for remeshed vortex methods},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/hejlesen2015c.pdf},
    volume = {280},
    year = {2015}
    }

  • P. R. Jones, X. Hao, E. R. Cruz-Chu, K. Rykaczewski, K. Nandy, T. M. Schutzius, K. K. Varanasi, C. M. Megaridis, J. H. Walther, P. Koumoutsakos, H. D. Espinosa, and N. A. Patankar, “Sustaining dry surfaces under water,” Sci. Rep.-UK, vol. 5, iss. 1, 2015.
    [BibTeX] [Abstract] [PDF] [DOI]

    Rough surfaces immersed under water remain practically dry if the liquid-solid contact is on roughness peaks, while the roughness valleys are filled with gas. Mechanisms that prevent water from invading the valleys are well studied. However, to remain practically dry under water, additional mechanisms need consideration. This is because trapped gas (e.g. air) in the roughness valleys can dissolve into the water pool, leading to invasion. Additionally, water vapor can also occupy the roughness valleys of immersed surfaces. If water vapor condenses, that too leads to invasion. These effects have not been investigated, and are critically important to maintain surfaces dry under water. In this work, we identify the critical roughness scale, below which it is possible to sustain the vapor phase of water and/or trapped gases in roughness valleys {–} thus keeping the immersed surface dry. Theoretical predictions are consistent with molecular dynamics simulations and experiments.

    @article{jones2015a,
    author = {Paul R. Jones and Xiuqing Hao and Eduardo R. Cruz-Chu and Konrad Rykaczewski and Krishanu Nandy and Thomas M. Schutzius and Kripa K. Varanasi and Constantine M. Megaridis and Jens H. Walther and Petros Koumoutsakos and Horacio D. Espinosa and Neelesh A. Patankar},
    doi = {10.1038/srep12311},
    journal = {{Sci. Rep.-UK}},
    month = {aug},
    number = {1},
    publisher = {Springer Nature},
    title = {Sustaining dry surfaces under water},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/jones2015a.pdf},
    volume = {5},
    year = {2015}
    }

  • A. Popadić, M. Praprotnik, P. Koumoutsakos, and J. H. Walther, “Continuum simulations of water flow past fullerene molecules,” Eur. Phys. J.-Spec. Top., vol. 224, iss. 12, p. 2321–2330, 2015.
    [BibTeX] [Abstract] [PDF] [DOI]

    We present continuum simulations of water flow past fullerene molecules. The governing Navier-Stokes equations are complemented with the Navier slip boundary condition with a slip length that is extracted from related molecular dynamics simulations. We find that several quantities of interest as computed by the present model are in good agreement with results from atomistic and atomistic-continuum simulations at a fraction of the cost. We simulate the flow past a single fullerene and an array of fullerenes and demonstrate that such nanoscale flows can be computed efficiently by continuum flow solvers, allowing for investigations into spatiotemporal scales inaccessible to atomistic simulations.

    @article{popadic2015a,
    author = {A. Popadi{\'{c}} and M. Praprotnik and P. Koumoutsakos and J. H. Walther},
    doi = {10.1140/epjst/e2015-02414-y},
    journal = {{Eur. Phys. J.-Spec. Top.}},
    month = {jun},
    number = {12},
    pages = {2321--2330},
    publisher = {Springer Nature},
    title = {Continuum simulations of water flow past fullerene molecules},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/popadic2015a.pdf},
    volume = {224},
    year = {2015}
    }

  • E. Oyarzua, J. H. Walther, A. Mejía, and H. A. Zambrano, “Early regimes of water capillary flow in slit silica nanochannels,” Phys. chem. chem. phys., vol. 17, iss. 22, p. 14731–14739, 2015.
    [BibTeX] [PDF] [DOI]
    @article{oyarzua2015a,
    author = {Elton Oyarzua and Jens H. Walther and Andr{\'{e}}s Mej{\'{\i}}a and Harvey A. Zambrano},
    doi = {10.1039/c5cp01862e},
    journal = {Phys. Chem. Chem. Phys.},
    number = {22},
    pages = {14731--14739},
    publisher = {Royal Society of Chemistry ({RSC})},
    title = {Early regimes of water capillary flow in slit silica nanochannels},
    url = {http://www.cse-lab.ethz.ch/wp-content/papercite-data/pdf/oyarzua2015a.pdf},
    volume = {17},
    year = {2015}
    }