Browsing by Author "Andreassen, Øyvind"

Now showing items 1-16 of 16

    • Assessment of the dispersion of Legionella-containing aerosols from a biological treatment plant 

      Blatny, Janet Martha; Tutkun, Murat; Fossum, Hannibal Eie; Skogan, Gunnar; Fykse, Else-Marie; Andreassen, Øyvind; Waagen, Viggo; Reif, Bjørn Anders Pettersson (2011)
      Legionella was detected in aeration ponds (biological treatment plant) at Borregaard Ind. Ltd., Norway, and in air samples harvested directly above these ponds. Since 2005, three outbreaks of legionellosis occurred within ...

    • Comparative visualization of multiple time surfaces by planar surface reformation 

      Brambilla, Andrea; Angelelli, Paolo; Andreassen, Øyvind; Hauser, Helwig (2016)
      Comparing time surfaces at different integration time points, or from different seeding areas, can provide valuable insight into transport phenomena of fluid flows. Such a comparative study is challenging due to the often ...

    • Damper models and their impact on shock response 

      Andreassen, Øyvind (2022-10-26)
      Mechanical vibration and shocks may be devastating, in particular to military equipment. Therefore, vibration and shock damping are of crucial importance to military hardware. Vibrations can cause material fatigue. They ...

    • Energy-scale Aware Feature Extraction for Flow Visualization 

      Pobitzer, Armin; Tutkun, Murat; Andreassen, Øyvind; Fuchs, R; Peikert, Ronald; Hauser, Helwig (2011)
      In the visualization of flow simulation data, feature detectors often tend to result in overly rich response, making some sort of filtering or simplification necessary to convey meaningful images. In this paper we present ...

    • Et estimat av effekten fra fly-genererte virvler på bebyggelse i nærheten av Kjevik flyplass 

      Andreassen, Øyvind; Langseth, Jan Olav (2000)
      At some occations, gusty winds caused by aircrafts during approach to Kjevik airport. have caused tiles to fall down from roofs, causing potential damage. In the current study, initiated by the Norwegian airtraffic and ...

    • Flow noise reduction from superhydrophobic surfaces 

      Elboth, Thomas; Reif, Bjørn Anders Pettersson; Andreassen, Øyvind; Martell, Michael B. (2012)
      This work investigates how a highly (super)hydrophobic surface can be used to reduce turbulence-generated drag and noise on a towed streamer cable. The work is done by analyzing full-scale drag and flow noise measurements ...

    • The impact of flow noise on towed and hull mounted acoustical sensors : an introductory study 

      Reif, Bjørn Anders Pettersson; Andreassen, Øyvind (2004)
      In this introductory study we have assessed the impact of turbulence generated wall-pressure fluctuations on surfacemounted acoustical sensors, with a special focus on towed sonar arrays. The main findings are that the ...

    • Introduction to shock-response spectra 

      Andreassen, Øyvind (2020-11-21)
      A shock is a sudden and violent event. There are many examples of shocks, from earth quakes and explosions to controlled mechanical transient processes. In this report, we discuss theory, modeling and analysis methods ...

    • Målinger av hastighetsfelter i flygenererte virvler nær hus under innflyvningstraseen ved Kjevik flyplass 

      Andreassen, Øyvind; Helgeland, Anders (2001)
      Winds caused by aircraft generated vortices are measured close to a roof in the approach to Kjevik airport. It is reported that aircraft vortices have caused tiles to fall down from roofs. In this report measurements of ...

    • Rotoboost heat exchanger 

      Wingstedt, Kristoffer; Andreassen, Øyvind (2012-11-22)
      In this report the fluid dynamical aspects of a rotating heat exchanger have been investigated. This work is a continuation of the work by Andreassen (2012) and in this report we emphasize on numerical computations on a ...

    • Sampling and identification of Legionella spp. at Borregaard Ind. Ltd. 

      Blatny, Janet Martha; Skogan, Gunnar; Reif, Bjørn Anders Pettersson; Andreassen, Øyvind; Thomassen, Gunn Merethe; Aarskaug, Tone; Fykse, Else Marie; Olsen, Jaran Strand (2007)
      Befolkningen i Sarpsborg/Fredrikstad-området opplevde et utbrudd forårsaket av Legionella pneumophila serogruppe 1 i mai 2005 hvor 56 personer ble registrert smittet. Skrubberanlegget ved Borregaard i Sarpsborg ble ...

    • Studies of aerodynamically induced vibrations on the P-3Cmaritime surveillance aircraft and proposed vibration reducing measures 

      Andreassen, Øyvind; Wasberg, Carl Erik; Helgeland, Anders; Tutkun, Murat; Kielland, Jan Charles; Reif, Bjørn Anders Pettersson; Skaugen, Atle (2013-01-31)
      After installation of a radome on the P-3C aircraft, vibrations occur in flight that were not present earlier. The vibrations are specially noticeable at high airspeeds. The cause of the vibrations is confirmed to be ...

    • Tensor analysis applied to the equations of contiuum mechanics I 

      Andreassen, Øyvind (2014-01-27)
      The Navier-Stokes equations, the Euler equations, the equations of elasticity and expressions derived from those, are in most cases treated in Cartesian coordinates. In some cases it can necessary to handle those equations ...

    • A theoretical study of small scale turbulence in stratified turbulent shear flows 

      Reif, Bjørn Anders Pettersson; Andreassen, Øyvind (2004)
      This report examines the postulate of local isotropy in stratified homogeneous turbulence from a theoretical point of view. The study is based on a priori analysis of the evolution equations governing single-point turbulence ...

    • Tracking airborne Legionella and Legionella pneumophila at a biological treatment plant 

      Blatny, Janet Martha; Reif, Bjørn Anders Pettersson; Skogan, Gunnar; Andreassen, Øyvind; Høiby, Ernst Arne; Ask, Eirik; Waagen, Viggo; Aanonsen, Dag; Aaberge, Ingeborg Aase S.; Caugant, Dominique A (2008)
      Biological treatment plants are frequently used to degrade organic substances in wastewater from wood refinement processes. Aeration ponds in such plants provide an optimal growth environment for many microorganisms, ...

    • Variational multiscale turbulence modeling in a high-order spectral element method 

      Gjesdal, Thor; Wasberg, Carl Erik; Reif, Bjørn Anders Pettersson; Andreassen, Øyvind (2006)
      One of the more promising recent approaches to turbulence modelling is the Variational Myltiscale Large Eddy Simulation (VMS LES) method proposed by Hughes et al.[Comp. Visual. Sci., vol 3, pp 47-59, 2000]. This method avoids ...