Bjørn Anders Pettersson Reif

• Osnes, Andreas Nygård; Vartdal, Magnus; Omang, Marianne Gjestvold & Reif, Bjørn Anders Pettersson (2020). Particle-resolved simulations of shock-induced flow through particle clouds at different Reynolds numbers. Physical Review Fluids. ISSN 2469-990X. 5(1). doi: 10.1103/PhysRevFluids.5.014305. Fulltekst i vitenarkiv
• Osnes, Andreas Nygård; Vartdal, Magnus; Omang, Marianne Gjestvold & Reif, Bjørn Anders Pettersson (2019). Numerical investigation of shock wave particle cloud interaction in cylindrical geometries. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT’19 - 10th National Conference on Computational Mechanics (Trondheim, Norway, 3-4 June 2019). International Center for Numerical Methods in Engineering (CIMNE). ISSN 978-84-949194-9-7. s. 285–310.
• Osnes, Andreas Nygård; Vartdal, Magnus; Omang, Marianne Gjestvold & Reif, Bjørn Anders Pettersson (2019). Computational analysis of shock-induced flow through stationary particle clouds. International Journal of Multiphase Flow. ISSN 0301-9322. 114, s. 268–286. doi: 10.1016/j.ijmultiphaseflow.2019.03.010. Fulltekst i vitenarkiv Vis sammendrag

  We investigate the shock-induced flow through random particle arrays using particle-resolved Large Eddy Simulations for different incident shock wave Mach numbers, particle volume fractions and particle sizes. We analyze trends in mean flow quantities and the unresolved terms in the volume averaged momentum equation, as we vary the three parameters. We find that the shock wave attenuation and certain mean flow trends can be predicted by the opacity of the particle cloud, which is a function of particle size and particle volume fraction. We show that the Reynolds stress field plays an important role in the momentum balance at the particle cloud edges, and therefore strongly affects the reflected shock wave strength. The Reynolds stress was found to be insensitive to particle size, but strongly dependent on particle volume fraction. It is in better agreement with results from simulations of flow through particle clouds at fixed mean slip Reynolds numbers in the incompressible regime, than with results from other shock wave particle cloud studies, which have utilized either inviscid or two-dimensional approaches. We propose an algebraic model for the streamwise Reynolds stress based on the observation that the separated flow regions are the primary contributions to the Reynolds stress.

• (2017). Numerical simulation of particle jet formation induced by shock wave acceleration in a Hele-Shaw cell. Shock Waves. ISSN 0938-1287. s. 1–11. doi: 10.1007/s00193-017-0778-9. Vis sammendrag

  The formation of jets from a shock-accelerated cylindrical shell of particles, confined in a Hele-Shaw cell, is studied by means of numerical simulation. A number of simulations have been performed, systematically varying the coupling between the gas and solid phases in an effort to identify the primary mechanism(s) responsible for jet formation. We find that coupling through drag is sufficient for the formation of jets. Including the effect of particle volume fraction and particle collisions did not alter the general behaviour, but had some influence on the length, spacing and number of jets. Furthermore, we find that the jet selection process starts early in the dispersal process, during the initial expansion of the particle layer.

• Wingstedt, Emma My Maria; Vartdal, Magnus & Reif, Bjørn Anders Pettersson (2017). Large-eddy simulations of dense-gas dispersion within a high-Reynolds number turbulent boundary layer. Physics of Fluids. ISSN 1070-6631. 29(9). doi: 10.1063/1.4999466.
• Wingstedt, Emma My Maria; Osnes, Andreas Nygård; Åkervik, Espen; Eriksson, Daniel & Reif, Bjørn Anders Pettersson (2017). Large-eddy simulation of dense gas dispersion over a simplified urban area. Atmospheric Environment. ISSN 1352-2310. 152, s. 605–616. doi: 10.1016/j.atmosenv.2016.12.039.
• Wingstedt, Emma My Maria; Fossum, Hannibal Eie; Reif, Bjørn Anders Pettersson & Werne, Joseph (2015). Anisotropy and shear-layer edge dynamics of statistically unsteady,stratified turbulence. Physics of Fluids. ISSN 1070-6631. 27(6). doi: 10.1063/1.4922238.
• Abdul-Karim, Nadia; Blackman, Christopher S.; Gill, Philip P.; Wingstedt, Emma My Maria & Reif, Bjørn Anders Pettersson (2014). Post-blast explosive residue-a review of formation and dispersion theories and experimental research. RSC Advances. ISSN 2046-2069. 4(97), s. 54354–54371. doi: 10.1039/c4ra04195j.
• Helgeland, Anders; Mardal, Kent-Andre; Haughton, Victor & Reif, Bjørn Anders Pettersson (2014). Numerical simulations of the pulsating flow of cerebrospinal fluid flow in the cervical spinal canal of a Chiari patient. Journal of Biomechanics. ISSN 0021-9290. 47(5), s. 1082–1090. doi: 10.1016/j.jbiomech.2013.12.023.
• Fossum, Hannibal Eie; Wingstedt, Emma My Maria & Reif, Bjørn Anders Pettersson (2013). A model for the viscous dissipation rate in stably stratified, sheared turbulence. Geophysical Research Letters. ISSN 0094-8276. 40(14), s. 3744–3749. doi: 10.1002/grl.50663. Vis sammendrag

  A model for the turbulence dissipation rate in stably stratified shear turbulence is developed and validated. The functional dependence of the model is derived from first principles and it represents a conceptually new approach in that it depends on the background temperature field rather than on the fluctuating velocity field. This novel feature makes the proposed model a viable candidate for dissipation rate estimates in measured real-life flows. Direct numerical simulation data are used for a priori assessment of the proposed model. It is demonstrated that the proposed model performs very well, particularly in cases where the background stratification becomes dynamically important. Also, a generalized expression for the mixing coefficient has been rigorously derived from first principles assuming local isotropy of incompressible turbulent flows. The mixing coefficient is shown to depend on the Prandtl number and values are in correspondence with previous studies.

• Fossum, Hannibal Eie; Reif, Bjørn Anders Pettersson; Tutkun, Murat & Gjesdal, Thor (2012). On the Use of Computational Fluid Dynamics to Investigate Aerosol Dispersion in an Industrial Environment: A Case Study. Boundary-Layer Meteorology. ISSN 0006-8314. 144(1), s. 21–40. doi: 10.1007/s10546-012-9711-z.
• Elboth, Thomas; Reif, Bjørn Anders Pettersson; Andreassen, Øyvind & Martell, Michael B. (2012). Flow noise reduction from superhydrophobic surfaces. Geophysics. ISSN 0016-8033. 77(1), s. P1–P10. doi: 10.1190/GEO2011-0001.1.
• Blatny, Janet Martha; Olsen, Jaran Strand; Andreassen, Øyvind; Waagen, Viggo & Reif, Bjørn Anders Pettersson (2011). Tracking Legionella in air generated from a biological treatment plant - A case study of the outbreak of legionellosis in Norway. Proceedings of SPIE, the International Society for Optical Engineering. ISSN 0277-786X. 8018. doi: 10.1117/12.886932.
• Wingstedt, Emma My Maria; Vik, Thomas & Reif, Bjørn Anders Pettersson (2011). Numerical simulation of non-neutral gas dispersion in a complex urban area. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'11: Sixth National Conference on Computational Mechanics, Trondheim 23-24 May 2011. Tapir Akademisk Forlag. ISSN 978-82-519-2798-7. s. 463–471.
• Valen-Senstad, Kristian; Mardal, Kent-Andre; Mortensen, Mikael; Reif, Bjørn Anders Pettersson & Langtangen, Hans Petter (2011). On The Complexity of Stationary Flow in Patient–Specific Aneurysms. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'11: Sixth National Conference on Computational Mechanics, Trondheim 23-24 May 2011. Tapir Akademisk Forlag. ISSN 978-82-519-2798-7.
• Valen-Senstad, Kristian; Mardal, Kent-Andre; Mortensen, Mikael; Reif, Bjørn Anders Pettersson & Langtangen, Hans Petter (2011). Direct numerical simulation of transitional flow in a patient-specific intracranial aneurysm. Journal of Biomechanics. ISSN 0021-9290. 44(16), s. 2826–2832. doi: 10.1016/j.jbiomech.2011.08.015.
• Blatny, Janet Martha; Tutkun, Murat; Fossum, Hannibal Eie; Skogan, Gunnar; Fykse, Else-Marie & Andreassen, Øyvind (2011). Assessment of the dispersion of Legionella-containing aerosols from a biological treatment plant. Frontiers in Bioscience. ISSN 1093-9946. June(1), s. 1300–1309. doi: 10.2741/e333.
• Elboth, Thomas; Reif, Bjørn Anders Pettersson & Andreassen, Øyvind (2011). Hydrodynamic flow noise reduction from superhydrophobic surfaces. Geophysics. ISSN 0016-8033. doi: 10.1190/geo2011-0001.1.
• Grafsrønningen, Stig; Jensen, Atle & Reif, Bjørn Anders Pettersson (2011). PIV investigation of buoyant plume from natural convection heat transfer above a horizontal heated cylinder. International Journal of Heat and Mass Transfer. ISSN 0017-9310. 54(23-24), s. 4975–4987. doi: 10.1016/j.ijheatmasstransfer.2011.07.011.
• (2011). Large eddy simulations of the release of liquified chlorine from a pressurized tank into the atmosphere. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'11: Sixth National Conference on Computational Mechanics, Trondheim 23-24 May 2011. Tapir Akademisk Forlag. ISSN 978-82-519-2798-7.
• (2011). Modeling the evaporation from a thin liquid surface beneath a turbulent boundary layer. International journal of thermal sciences. ISSN 1290-0729. 50(12), s. 2311–2317. doi: 10.1016/j.ijthermalsci.2011.07.006.
• (2011). Flow Patterns and Aerosol Dispersion inside an Aerosol Test Chamber. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'11: Sixth National Conference on Computational Mechanics, Trondheim 23-24 May 2011. Tapir Akademisk Forlag. ISSN 978-82-519-2798-7. s. 73–87.
• Reif, Bjørn Anders Pettersson & Mortensen, Mikael (2011). A Nonlinear Eddy-Viscosity Model for Near-Wall Turbulence. ERCOFTAC Series. ISSN 1382-4309. 14, s. 269–276. doi: 10.1007/978-90-481-9603-6_28.
• Endregard, Monica; Reif, Bjørn Anders Pettersson; Vik, Thomas & Busmundrud, Odd (2010). Consequence assessment of indoor dispersion of sarin-A hypothetical scenario. Journal of Hazardous Materials. ISSN 0304-3894. 176(1-3), s. 381–388. doi: 10.1016/j.jhazmat.2009.11.041. Vis sammendrag

  The objective of this study is to provide a hypothetical scenario of indoor dispersion of the highly toxic nerve agent sarin in a large building, which can be used as a starting point for discussion, planning, training and exercises for emergency services and responsible authorities. The indoor dispersion has been simulated using a Computational Fluid Dynamics (CFD) approach. Possible consequences have been calculated based on concentration and dose profiles. Mild intoxication effects appear within minutes, while serious injuries and fatalities occur approximately 20 min after release. Anticipated key emergency response challenges are: (i) the time factor due to rapid onset of symptoms, (ii) the large number of casualties, and (iii) the contaminated hazard scene. (C) 2009 Elsevier B.V. All rights reserved.

• Mortensen, Mikael; Reif, Bjørn Anders Pettersson & Wasberg, Carl Erik (2010). Assessment of the finite volume method applied to the nu(2)-f model. International Journal for Numerical Methods in Fluids. ISSN 0271-2091. 63(4), s. 495–516. doi: 10.1002/fld.2091. Vis sammendrag

  The objective of this paper is to assess the accuracy of low-order finite volume (FV) methods applied to the nu(2)-f turbulence model of Durbin (Theoret. Comput. Fluid Dyn. 1991; 3:1-13) in the near vicinity of solid walls. We are not (like many others) concerned with the stability of solvers - the topic at hand is simply whether the mathematical properties of the nu(2)-f model can be captured by the given, widespread, numerical method. The nu(2)-f model is integrated all the way up to solid walls, where steep gradients in turbulence parameters are observed. The full resolution of wall gradients imposes quite high demands on the numerical schemes and it is not evident that common (second order) FV codes can fully cope with such demands. The nu(2)-f model is studied in a statistically one-dimensional, fully developed channel flow where we compare FV schemes with a highly accurate spectral element reference implementation. For the FV method a higher-order face interpolation scheme, using Lagrange interpolation polynomials up to arbitrary order, is described. It is concluded that a regular second-order FV scheme cannot give an accurate representation of all model parameters, independent of mesh density. To match the spectral element solution an extended source treatment (we use three-point Gauss-Lobatto quadrature), as well as a higher-order discretization of diffusion is required. Furthermore, it is found that the location of the first internal node need to be well within y(+) = 1. Copyright (C) 2009 John Wiley & Sons, Ltd.

• Elboth, Thomas; Lilja, Didrik; Reif, Bjørn Anders Pettersson & Andreassen, Øyvind (2010). Investigation of flow and flow noise around a seismic streamer cable. Geophysics. ISSN 0016-8033. 75(1), s. Q1–Q9. doi: 10.1190/1.3294639.
• Valen-Sendstad, Kristian; Mortensen, M.; Langtangen, Hans Petter; Reif, Bjørn Anders Pettersson & Mardal, Kent-Andre (2009). Implementing a k-e Turbulence Model in the FEniCS Finite Element Programming Environment. I Skallerud, Bjørn & Andersson, Helge (Red.), Proceedings of MekIT'09. Tapir Akademisk Forlag. ISSN 978-82-519-2421-4.
• Elboth, Thomas; Reif, Bjørn Anders Pettersson & Andreassen, Øyvind (2009). Flow and swell noise in marine seismic data. Geophysics. ISSN 0016-8033. 74(2), s. Q17–Q25. doi: 10.1190/1.3078403.
• (2009). Variational multiscale turbulence modelling in a high order spectral element method. Journal of Computational Physics. ISSN 0021-9991. 228(19), s. 7333–7356. doi: 10.1016/j.jcp.2009.06.029. Vis sammendrag

  In the variational multiscale (VMS) approach to large eddy simulation (LES), the governing equations are projected onto an a priori scale partitioning of the solution space. This gives an alternative framework for designing and analyzing turbulence models. We describe the implementation of the VMS LES methodology in a high order spectral element method with a nodal basis, and discuss the properties of the proposed scale partitioning. The spectral element code is first validated by doing a direct numerical simulation of fully developed plane channel flow. The performance of the turbulence model is then assessed by several coarse grid simulations of channel flow at different Reynolds numbers. (C) 2009 Elsevier Inc. All rights reserved.

• Reif, Bjørn Anders Pettersson; Mortensen, Mikael & Langer, Carlos A. (2009). Towards Sensitizing the Nonlinear v(2)-f Model to Turbulence Structures. Flow Turbulence and Combustion. ISSN 1386-6184. 83(2), s. 185–203. doi: 10.1007/s10494-008-9194-7. Vis sammendrag

  In this paper a one-way coupling between the nonlinear v (2) -aEuro parts per thousand f model by Pettersson Reif (Flow Turbul Combust 76:241-256, 2006) and an algebraic structure-based model have been investigated. Comparisons with available experimental and numerical data indicate that the compatibility between the two models is good and that their joint performance is satisfactory in the cases considered here. A full coupling between the models seems therefore a potentially viable route towards a significant advancement of engineering turbulence models and their predictive capabilities.

• (2009). Predicting particle deposition in the human airways with RANS turbulence modeling. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'09 : Fifth National Conference on Computational Mechanics, Trondheim 26-27 May 2009. Tapir Akademisk Forlag. ISSN 978-82-519-2421-4. s. 169–186.
• (2009). Numerical simulation of aerosol dispersion inside a rotating aerosol chamber. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'09 : Fifth National Conference on Computational Mechanics, Trondheim 26-27 May 2009. Tapir Akademisk Forlag. ISSN 978-82-519-2421-4. s. 459–470.
• Elboth, Thomas; Wasberg, Carl Erik; Helgeland, Anders; Andreassen, Øyvind & Reif, Bjørn Anders Pettersson (2009). Flow noise simulation around a cylinder. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'09 : Fifth National Conference on Computational Mechanics, Trondheim 26-27 May 2009. Tapir Akademisk Forlag. ISSN 978-82-519-2421-4. s. 151–168.
• Elboth, Thomas; Helgeland, Anders; Andreassen, Øyvind & Reif, Bjørn Anders Pettersson (2009). Flow noise simulation around a cylinder. I Skallerud, Bjørn Helge & Andersson, Helge Ingolf (Red.), MekIT'09 : Fifth National Conference on Computational Mechanics, Trondheim 26-27 May 2009. Tapir Akademisk Forlag. ISSN 978-82-519-2421-4. s. 151–168.
• Blatny, Janet Martha; Reif, Bjørn Anders Pettersson; Skogan, Gunnar; Andreassen, Øyvind; Høiby, Ernst Arne & Ask, Eirik (2008). Tracking airborne Legionella and Legionella pneumophila at a biological treatment plant. Environmental Science and Technology. ISSN 0013-936X. 42(19), s. 7360–7367. doi: 10.1021/es800306m. Fulltekst i vitenarkiv
• Reif, Bjørn Anders Pettersson; Mortensen, Mikael & Langer, Carlos A. (2008). Towards Sensitizing the Nonlinear v^2-f Model to Turbulence Structures. Flow Turbulence and Combustion. ISSN 1386-6184. doi: 10.1007/s10494-008-9194-7.
• (2007). Visualization of vorticity and vortices in wall-bounded turbulent flows. IEEE Transactions on Visualization and Computer Graphics. ISSN 1077-2626. 13(5), s. 1055–1066. doi: 10.1109/TVCG.2007.1062. Vis sammendrag

  This study was initiated by the scientifically interesting prospect of applying advanced visualization techniques to gain further insight into various spatio-temporal characteristics of turbulent flows. The ability to study complex kinematical and dynamical features of turbulence provides means of extracting the underlying physics of turbulent fluid motion. The objective is to analyze the use of a vorticity field line approach to study numerically generated incompressible turbulent flows. In order to study the vorticity field, we present a field line animation technique that uses a specialized particle advection and seeding strategy. Efficient analysis is achieved by decoupling the rendering stage from the preceding stages of the visualization method. This allows interactive exploration of multiple fields simultaneously, which sets the stage for a more complete analysis of the flow field. Multifield visualizations are obtained using a flexible volume rendering framework, which is presented in this paper. Vorticity field lines have been employed as indicators to provide a means to identify "ejection" and "sweep" regions, two particularly important spatio-temporal events in wall-bounded turbulent flows. Their relation to the rate of turbulent kinetic energy production and viscous dissipation, respectively, has been identified.

• (2007). On Vorticity, vortices and material lines in turbulent channel flow. I Palma, J.M.L.M. & Lopes, A. Silva (Red.), Advances in Turbulence XI, Proceedings of the 11th European Turbulence Conference. Springer. ISSN 978-3-540-72603-6. s. 767–767.
• (2007). On Vorticity and Vortices in Wall-Bounded Turbulent Flows. I Skallerud, B. & Andersson, H.I. (Red.), MEKIT'07 Fourth National Conference on Computational Mechanics. Tapir Akademisk Forlag. ISSN 978-82-519-2235-7. s. 163–174.
• (2006). Spectral element benchmark simulations of natural convection in two-dimensional cavities. International Journal for Numerical Methods in Fluids. ISSN 0271-2091. 50, s. 1297–1319. doi: 10.1002/d.1121.
• (2005). Application of a variational multiscale turbulence model in a high order spectral element solver. I Skallerud, B & Andersson, H. I. (Red.), MEkIT'05. Third national conference on Computational Mechanics. Tapir Akademisk Forlag. ISSN 8251920523. s. 101–116.
• (2003). Large-eddy simulation of flow around a wall-mounted rounded cylinder, MekIT'03, Second national conference on Computational Mechanics, Trondheim 8-9 May 2003. Tapir Akademisk Forlag. ISSN 82-519-1868-5. s. 391–405.
• (2001). Numerical simulation of turbulence by spectral element methods, MekIT'01 - First national conference on Computational Mechanics. Tapir Akademisk Forlag. ISSN 82-519-1662-3. s. 387–402. Vis sammendrag

  Proceedings from the first national conference on computational mechanics includes 30 papers presented during the conference, which took place in Trondheim 3-4 May 2001. The Proceedings, which contains contributions both from industry and academia, gives the state-of-the-art in the field in Norway.

Se alle arbeider i Cristin

• Durbin, Paul & Reif, Bjørn Anders Pettersson (2010). Statistical Theory and Modeling for Turbulent Flows. John Wiley & Sons. ISBN 978-0-470-68931-8. 344 s.

Se alle arbeider i Cristin

• (2018). Analysis of carrier phase fluctuations during the passage of a shock wave through a particle cloud.
• (2016). Jetting instability of a shocked cylindrical shell of solid particles.
• Wingstedt, Emma My Maria; Eriksson, Daniel; Parmhed, Oskar; Leroy, Guillaume; Osnes, Andreas Nygård & Reif, Bjørn Anders Pettersson (2016). MODITIC - Large-eddy simulations of dispersion of neutral and non-neutral scalar fields in complex urban-like geometries.
• Endregard, Monica; Burkhart, Stephane; Burman, Jan; Gentilhomme, Olivier; Robins, Alan & Wingstedt, Emma My Maria [Vis alle 12 forfattere av denne artikkelen] (2016). MODITIC - Modelling the dispersion of toxic industrial chemicals in urban environments.
• (2014). Numerical Simulation of the Dispersion of Chlorine Following the Release from a Pressurized Tank.
• Wingstedt, Emma My Maria; Fossum, Hannibal Eie & Reif, Bjørn Anders Pettersson (2013). Modelling the viscous dissipation rate in stably stratified turbulence.
• (2013). Evaporation of a thin liquid surface beneath a turbulent boundary layer.
• Vik, Thomas; Wingstedt, Emma My Maria; Tørnes, John Aasulf; Reif, Bjørn Anders Pettersson & Endregard, Monica (2013). Numerical simulations of the dispersion of non-neutral toxic industrial chemicals in an urban environment.
• Vik, Thomas; Wingstedt, Emma My Maria & Reif, Bjørn Anders Pettersson (2012). Numerical simulation of the dispersion of ammonia in complex urban environment.
• Grafsrønningen, Stig; Jensen, Atle & Reif, Bjørn Anders Pettersson (2012). PIV investigation of a buoyant plume above heated horizontal cylinder.
• (2011). Large eddy simulations of the release of liquified chlorine from a pressurized tank into the atmosphere.
• (2011). Large Eddy Simulations of the Release of Liquified Chlorine from a Pressurized Tank into the Atmosphere.
• (2009). Large eddy simulations of the evaporation from a liquid pool beneath a turbulent air flow.
• (2009). CFD simulations of the evaporation from a liquid pool in a turbulent flow.
• Endregard, Monica; Reif, Bjørn Anders Pettersson; Vik, Thomas & Busmundrud, Odd (2009). Consequence management challenges after indoor dispersion of a toxic chemical.
• Elboth, Thomas; Andreassen, Øyvind & Reif, Bjørn Anders Pettersson (2008). Experiments and simulations of flow noise inside a cylinder aligned with the flow.
• Mortensen, Mikael; Reif, Bjørn Anders Pettersson & Langer, Carlos A. (2008). Modelling adverse pressure-gradient boundary layers using the nonlinear V2F model in combination with a structure based model.
• Helgeland, Anders; Andreassen, Øyvind; Ommundsen, Atle; Reif, Bjørn Anders Pettersson; Werne, Joseph & Gaarder, Trond (2004). Visualization of the energy-containing turbulent scales.
• Osnes, Andreas Nygård; Vartdal, Magnus; Reif, Bjørn Anders Pettersson & Omang, Marianne Gjestvold (2019). Shock-induced flow through particle clouds. Universitetet i Oslo. Vis sammendrag

  High-speed flows through dense particle clouds occur in many technological applications such as explosion mitigation systems, combustion engines, drug-delivery systems, as well as natural phenomena such as volcanic eruptions and meteoroid breakup. This thesis studies such flows by means of numerical simulations. Typical flows of interest feature trillions of particles, and it is therefore necessary to use simplified models to describe the behaviour of the particles and the flow around them. In this thesis, we use very large, accurate, simulations to study the details of shock-induced flows with a moderate number of particles. In addition, full-scale simulations with a large number of particles are used to determine the sensitivity of such simulations to modelling choices. The simulations with few particles show that high particle concentration necessitates modifications to the drag-laws and flow model approximations that are used to simulate full-scale problems. Small-scale flow fluctuations affect the average flow statistics, and must be modelled in simulations where they are not directly captured. The full-scale simulations show that the shock-accelerated particles self-organise and form particle jets, in agreement with experiments. To capture this process, the simulations must account for the interchange of momentum and energy between the particles and the surrounding air.

Se alle arbeider i Cristin