@inproceedings{SchmidtKerstein, author = {Schmidt, Heiko and Kerstein, Alan R.}, title = {Towards a multiscale strategy for modeling high-pressure flow of carbon dioxide for sequestration}, series = {Geoenergy 2010, Potsdam, Germany}, booktitle = {Geoenergy 2010, Potsdam, Germany}, pages = {2}, language = {en} } @inproceedings{NedelecSchmidtWunschetal., author = {N{\´e}d{\´e}lec, Renaud and Schmidt, Heiko and Wunsch, Scott and Sayler, Ben J. and Kerstein, Alan R.}, title = {Comparison of Entrainment Rates from a Tank Experiment with Results Us- ing the One-Dimensional-Turbulence Model}, series = {EGU General Assembly 2010, held in Vienna, Austria, 02 - 07 May 2010}, booktitle = {EGU General Assembly 2010, held in Vienna, Austria, 02 - 07 May 2010}, language = {en} } @inproceedings{OevermannSchmidtKerstein, author = {Oevermann, Michael and Schmidt, Heiko and Kerstein, Alan R.}, title = {Linear eddy modeling of n-heptane combustion in HCCI engines}, series = {12th SIAM International Conference on Numerical Combustion}, booktitle = {12th SIAM International Conference on Numerical Combustion}, pages = {S. 20}, language = {en} } @misc{SchmidtKersteinNedelecetal., author = {Schmidt, Heiko and Kerstein, Alan R. and N{\´e}d{\´e}lec, Renaud and Wunsch, Scott and Sayler, Ben J.}, title = {One-dimensional turbulence simulation of a laboratory analog of radiatively induced cloud-top entrainment}, language = {en} } @inproceedings{SchmidtSchulzKerstein, author = {Schmidt, Heiko and Schulz, Falko T. and Kerstein, Alan R.}, title = {Toward modeling of multi- phase flow patterns using a combination of level sets and one-dimensional turbulence}, series = {EGU General Assembly 2011, Vienna, Austria, 03 - 08 April 2011}, booktitle = {EGU General Assembly 2011, Vienna, Austria, 03 - 08 April 2011}, language = {en} } @misc{KersteinSchmidtNedelecetal., author = {Kerstein, Alan R. and Schmidt, Heiko and N{\´e}d{\´e}lec, Renaud and Wunsch, Scott and Sayler, Ben J.}, title = {Analysis and numerical simulation of a laboratory analog of radiatively induced cloud-top entrainment}, series = {Bulletin of the American Physical Society Dynamics}, volume = {55}, journal = {Bulletin of the American Physical Society Dynamics}, number = {16}, language = {en} } @inproceedings{GlaweKleinKersteinetal., author = {Glawe, Christoph and Klein, Rupert and Kerstein, Alan R. and Schmidt, Heiko}, title = {Towards the simulation of gravity waves using the One-Dimensional Turbulence model}, series = {EGU General Assembly 2012, held 22-27 April, 2012 in Vienna}, booktitle = {EGU General Assembly 2012, held 22-27 April, 2012 in Vienna}, language = {en} } @misc{SoniaRichterBrunneretal., author = {Sonia, G. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Mai, M. and Lenk, Friedrich and Bundesmann, J. and Pensl, G. and Schmidt, J. and Zeimer, U. and Wang, L. and Baskar, K. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {2 MeV ion irradiation effects on AlGaN/GaN HFET devices}, series = {Solid-State Electronics}, volume = {52}, journal = {Solid-State Electronics}, number = {7}, issn = {0038-1101}, pages = {1011 -- 1017}, abstract = {AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with 2 MeV protons, carbon, oxygen, iron and krypton ions with fluences ranging from 1 × 109 cm-2 to 1 × 1013 cm-2. DC, pulsed I-V characteristics, loadpull and S-parameters of the AlGaN HFET devices were measured before and after irradiation. In parallel, a thick GaN reference layer was also irradiated with the same ions and was characterized by X-ray diffraction, photoluminescence, Hall measurements before and after irradiation. Small changes in the device performance were observed after irradiation with carbon and oxygen at a fluence of 5 × 1010 cm-2. Remarkable changes in device characteristics were seen at a fluence of 1 × 1012 cm-2 for carbon, oxygen, iron and krypton irradiation. Similarly, remarkable changes were also observed in the GaN layer for irradiations with fluence of 1 × 1012 cm-2. The results found on devices and on the GaN layer were compared and correlated.}, language = {en} } @misc{GnanapragasamRichterBrunneretal., author = {Gnanapragasam, S. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Mai, M. and Lenk, Friedrich and Opitz-Coutureau, J. and Pensl, G. and Schmidt, J. and Zeimer, U. and Wang, L. and Krishnan, B. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {Irradiation effects on AlGaN HFET devices and GaN layers}, series = {Journal of Materials Science: Materials in Electronics}, volume = {19}, journal = {Journal of Materials Science: Materials in Electronics}, number = {1}, issn = {1573-482X}, doi = {10.1007/s10854-008-9589-1}, pages = {64 -- 67}, abstract = {AlGaN/GaN heterostructure field effect transistors (HFETs) were irradiated with protons as well as carbon, oxygen, iron and krypton ions of high (68 and 120 MeV) and low (2 MeV) energy with fluences in the range from 1x107 to 1x1013 cm-2. High energy irradiation with protons, carbon and oxygen produced no degradation in devices while krypton irradiation at the fluence of 1x1010 cm-2 resulted in a small reduction of 2\% in the transconductance. Similarly, for GaN samples irradiated with protons, carbon and oxygen at high energy no changes were seen by XRD, PL and Hall effect, while changes in lattice constant and a reduction in PL intensity were observed after irradiation with high energy krypton. Low energy irradiation with carbon and oxygen at a fluence of 5x1010 cm-2 results in small change in the device performance while remarkable changes in device characteristics are seen at a fluence of 1x1012 cm-2 for carbon, oxygen, iron and krypton irradiation. Similarly changes are also observed by XRD, PL and Hall effect for the thick GaN layer irradiated at the fluence of 1x1012 cm-2. The device results and GaN layer properties are strongly correlated.}, language = {en} } @misc{SoniaRichterBrunneretal., author = {Sonia, G. and Richter, E. and Brunner, F. and Denker, A. and Lossy, R. and Lenk, Friedrich and Opitz-Coutureau, J. and Mai, M. and Schmidt, J. and Zeimer, U. and Wang, L. and Baskar, K. and Weyers, M. and W{\"u}rfl, Joachim and Tr{\"a}nkle, G{\"u}nther}, title = {High energy irradiation effects on AlGaN/GaN HFET devices}, series = {Semiconductor Science and Technology}, volume = {22}, journal = {Semiconductor Science and Technology}, number = {11}, issn = {0268-1242}, doi = {10.1088/0268-1242/22/11/007}, pages = {1220 -- 1224}, abstract = {The effect of proton, carbon, oxygen and krypton irradiation on AlGaN HFET devices has been studied. Irradiation was performed at 68 and 120 MeV with fluences in the range from 1 × 10^7 to 1 × 10^13 cm2 . Before and after irradiation, dc and pulsed I - V characteristics, loadpull and S -parameters of the AlGaN HFET devices were measured. A thick GaN reference layer was characterized by x-ray diffraction, photoluminescence and Hall measurements before and after irradiation. Proton, carbon and oxygen irradiation show no degradation in devices while krypton irradiation shows a small change at a fluence of 1 × 10 10 cm2 in the device characteristics. The device results are correlated with the thick GaN results.}, language = {en} } @inproceedings{MovagharLinneOevermannetal., author = {Movaghar, Amirreza and Linne, Mark and Oevermann, Michael and Meiselbach, Falko T. and Schmidt, Heiko and Kerstein, Alan R.}, title = {Numerical study of liquid breakup at the surface of turbulent liquid jets using One-Dimensional Turbulence}, series = {26th Annual Conference on Liquid Atomization and Spray Systems, ILASS, proceedings of the Conference, Bremen, Germany, 08.09.2014 - 10.09.2014}, booktitle = {26th Annual Conference on Liquid Atomization and Spray Systems, ILASS, proceedings of the Conference, Bremen, Germany, 08.09.2014 - 10.09.2014}, address = {Bremen}, isbn = {978-3-00-047070-7}, abstract = {This paper presents an investigation of primary breakup of planar turbulent liquid jets and breakup properties at the surface of turbulent jets in still air at standard conditions. Numerical simulations are carried out for jet exit Reynolds number 23000 and Weber numbers in the range [102-107]. Due to the limitation of direct numerical simulation (DNS) to moderate Reynolds numbers, a stochastic 1D ansatz based on the one-dimensional turbulence (ODT) model is used to simulate a planar liquid jet with a high lateral resolution. ODT permits an affordable high resolution of interface and single-phase property gradients which are key for understanding the local behavior. ODT is a stochastic model simulating turbulent flow evolution along a notional 1D line of sight by applying instantaneous maps to represent the effect of individual turbulent eddies on property profiles. The most relevant mechanisms that influence the primary breakup of liquid jets are found to be represented accurately based on comparisons to experiments and correlations reported in the literature. Building on this finding, future work will focus on the statistics of droplets generated by primary breakup, both to investigate their relationship to breakup mechanisms and to provide input to models of secondary breakup and subsequent spray evolution.}, language = {en} } @inproceedings{GlaweSchmidtKerstein, author = {Glawe, Christoph and Schmidt, Heiko and Kerstein, Alan R.}, title = {ODTLES: Mulitscale turbulence modeling and buoyant application}, series = {Book of abstracts, 7th European Postgraduate Fluid Dynamics Conference, Ilmenau, Germany, 14th - 17th, July 2014}, booktitle = {Book of abstracts, 7th European Postgraduate Fluid Dynamics Conference, Ilmenau, Germany, 14th - 17th, July 2014}, address = {Ilmenau}, pages = {S.46}, language = {en} } @misc{JozefikKersteinSchmidtetal., author = {Jozefik, Zoltan and Kerstein, Alan R. and Schmidt, Heiko and Lyra, Sgouria and Kolla, Hemanth and Chen, Jackie H.}, title = {One-dimensional turbulence modeling of a turbulent counterflow flame with comparison to DNS}, series = {Combustion and Flame}, volume = {162}, journal = {Combustion and Flame}, number = {8}, issn = {1556-2921}, pages = {2999 -- 3015}, language = {en} } @misc{SchmidtGlaweJozefiketal., author = {Schmidt, Heiko and Glawe, Christoph and Jozefik, Zoltan and Meiselbach, Falko T. and Kerstein, Alan R.}, title = {On the benefits of ODT-based stochastic turbulence modeling}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {14}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {1}, issn = {1617-7061}, pages = {655 -- 656}, abstract = {We summarize the group's progress in applying, analyzing, and improving ODT and ODT-based stochastic turbulence models like ODTLES. Compared to DNS these models span a wider range of scales while compared to RANS/LES (i) the molecular effects are retained and (ii) no assumption of scale separation is made. In this regard ODTLES has more properties of DNS than of standard LES.}, language = {en} }