Atle Jensen

• Rabault, Jean; Sutherland, Graig; Gundersen, Olav; Jensen, Atle; Marchenko, Aleksey & Breivik, Øyvind (2020). An open source, versatile, affordable waves in ice instrument for scientific measurements in the Polar Regions. Cold Regions Science and Technology.  ISSN 0165-232X.  170 . doi: 10.1016/j.coldregions.2019.102955
• Ramirez De La Torre, Reyna Guadalupe; Jensen, Atle & Kuchta, Miroslav (2020). Experiments on air entrainment produced by a circular free falling jet. International Journal of Multiphase Flow.  ISSN 0301-9322. . doi: https://doi.org/10.1016/j.ijmultiphaseflow.2020.103424 Show summary

  The process of a circular free falling jet entering an idle pool was studied with the objective of determining a relation between the naturally occurring disturbances on the jet surface and air entrainment. To this end the instabilities of the free falling jet were characterized and compared with the bubble count distribution and an estimated amount of entrained air in the plume. Different jet lengths were considered. The aeration process was captured through image sequences. Individ- ual analysis of each disturbance in the jet surface was made. Our results show that both the bubble count and entrained air have a linear relation with the steepness of the jet disturbances. Moreover, the wave-jet ratio is introduced, which defines an entrainment condition for all the studied cases.

• Vollestad, Petter; Angheluta, Luiza & Jensen, Atle (2020). Experimental study of secondary flows above rough and flat interfaces in horizontal gas-liquid pipe flow. International Journal of Multiphase Flow.  ISSN 0301-9322. . doi: https://doi.org/10.1016/j.ijmultiphaseflow.2020.103235
• Carr, Magda; Sutherland, Peter; Haase, Andrea; Evers, Karl-Ulrich; Fer, Ilker; Jensen, Atle; Kalisch, Henrik; Berntsen, Jarle; Părău, Emilian I.; Thiem, Øyvind & Davies, Peter A. (2019). Laboratory experiments on internal solitary waves in ice-covered waters. Geophysical Research Letters.  ISSN 0094-8276.  46(21), s 12230- 12238 . doi: 10.1029/2019GL084710 Full text in Research Archive.
• Mossige, Endre Joachim; Edvardsen, Bente; Jensen, Atle & Mielnik, Michal Marek (2019). A tunable, microfluidic filter for clog‑free concentration and separation of complex algal cells. Microfluidics and Nanofluidics.  ISSN 1613-4982.  23(56) . doi: 10.1007/s10404-019-2209-y Full text in Research Archive. Show summary

  An inherent problem with microfluidic filters is the tendency to clog, especially when applied to cells due to their geometrical complexity, deformability, and tendency to adhere to surfaces. In this work, we handle live algal cells of high complexity without signs of clogging, achieved by exploiting hydrodynamic interactions around trilobite-shaped filtration units. To characterize the influence of cell complexity on the separation and concentration mechanisms, we compare the hydrodynamic interactions to those of synthetic, rigid microparticles. We discover that simple rolling along the filter structures, which prevents clogging for particles, cannot be applied to cells. Instead, we find that inertial effects must be employed to minimize the filter interactions and that this modification leads to only a minor reduction in device performance.

• Rabault, Jean; Kuchta, Miroslav; Jensen, Atle; Reglade, Ulysse Antoine & Cerardi, Nicolas (2019). Artificial neural networks trained through deep reinforcement learning discover control strategies for active flow control. Journal of Fluid Mechanics.  ISSN 0022-1120.  865, s 281- 302 . doi: 10.1017/jfm.2019.62 Full text in Research Archive.
• Rabault, Jean; Sutherland, Graig; Jensen, Atle; Christensen, Kai Håkon & Marchenko, Aleksey (2019). Experiments on wave propagation in grease ice: combined wave gauges and particle image velocimetry measurements. Journal of Fluid Mechanics.  ISSN 0022-1120.  864, s 876- 898 . doi: 10.1017/jfm.2019.16 Full text in Research Archive.
• Sutherland, Graig; Rabault, Jean; Christensen, Kai Håkon & Jensen, Atle (2019). A two layer model for wave dissipation in sea ice. Applied Ocean Research.  ISSN 0141-1187.  88, s 111- 118 . doi: 10.1016/j.apor.2019.03.023 Full text in Research Archive.
• Vollestad, Petter; Ayati, Anis Awal; Angheluta, Luiza; Lacasce, Joseph Henry & Jensen, Atle (2019). Experimental investigation of airflow above waves in a horizontal pipe. International Journal of Multiphase Flow.  ISSN 0301-9322.  110, s 37- 49 . doi: 10.1016/j.ijmultiphaseflow.2018.08.008 Full text in Research Archive.
• Vollestad, Petter; Ayati, Anis Awal & Jensen, Atle (2019). Experimental investigation of intermittent airflow separation and microscale wave breaking in wavy two-phase pipe flow. Journal of Fluid Mechanics.  ISSN 0022-1120.  878, s 769- 819 . doi: 10.1017/jfm.2019.660 Full text in Research Archive.
• Vollestad, Petter; Ayati, Anis Awal & Jensen, Atle (2019). Microscale wave breaking in stratified air-water pipe flow. Physics of Fluids.  ISSN 1070-6631.  31(3), s 1- 19 . doi: 10.1063/1.5082607 Full text in Research Archive.
• Ayati, Anis Awal; Vollestad, Petter & Jensen, Atle (2018). Detailed measurements of interfacial dynamics in air-water pipe flow. Procedia IUTAM.  ISSN 2210-9838.  26, s 59- 69 . doi: 10.1016/j.piutam.2018.03.006 Full text in Research Archive.
• Dong, Tao; Shi, Zhongyuan & Jensen, Atle (2018). Bi-objective optimization of axial profile of pin fin with uniform base heat flux. Applied Thermal Engineering.  ISSN 1359-4311.  128, s 830- 836 . doi: 10.1016/j.applthermaleng.2017.09.037 Full text in Research Archive. Show summary

  Cone shaped pin fin with curved profile and uniform base heat flux was investigated. The result from simultaneous optimization in regard of fin efficiency and total volume is presented. The profile is represented by the Non-Uniform Rational B-Spline (NURBS) for an additional degree of freedom to morph during the optimization process. An overall dominance was obtained from the present work, as compared to the classic concave parabolic profile, the practical constraint in fabrication taken into consideration. The profiles corresponding to the acquired Pareto solution sets tend to comply with the constructal law of design, in which freestream of heat flow is expected.

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• Breivik, Øyvind; Rabault, Jean; Hole, Lars R; Christensen, Kai Håkon; Müller, Malte; Jensen, Atle & Mauritzen, Cecilie (2019). Bølger i isen påvirker Arktis. Å forstå isdønningene kan forbedre værvarsler og klimamodeller.. Forskning.no.  ISSN 1891-635X.
• Løken, Trygve Kvåle; Rabault, Jean; Jensen, Atle; Christensen, Kai Håkon & Müller, Malte (2019). Wave statistics from ship mounted sensors in the marginal ice zone.
• Marchenko, Aleksey; Haase, Andrea; Jensen, Atle; Lishman, Ben & Rabault, Jean (2019). Laboratory investigations of the bending rheology of floating saline ice and wave damping in the HSVA ice tank.
• Rabault, Jean; Jensen, Atle & Kuchta, Miroslav (2019). Deep Reinforcement Learning reduces cylinder drag in a 2D flow simulation: a first step towards novel Active Flow Control methodology?.
• Rabault, Jean; Sutherland, Graig J. & Jensen, Atle (2019). Measurements of sea ice drift and dynamics using an open source instrument.
• Rabault, Jean; Sutherland, Graig J. & Jensen, Atle (2019). Measurements of waves in ice using open source solutions: results from recent deployments in the Northwest Barents sea.
• Rabault, Jean; Sutherland, Graig; Marchenko, Aleksey & Jensen, Atle (2019). Diving into the Physics of Wave-Ice interaction: recent evidences of complex viscous dynamics.

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