Browsing Institutt for marin teknikk by Author "Jiang, Fengjian"
Now showing items 1-20 of 25
-
Asymmetric cellular bi-stability in the gap between tandem cylinders
Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge; Jiang, Fengjian (Peer reviewed; Journal article, 2023)In the gap region of tandem cylinders, within the reattachment regime, bi-stability is seen to be cellular. Direct numerical simulations at a Reynolds number of 500, and a gap ratio of 3.0, show that shedding of gap vortices ... -
Diameter ratio effects in the wake flow of single step cylinders
Tian, Cai; Jiang, Fengjian; Pettersen, Bjørnar; Andersson, Helge Ingolf (Peer reviewed; Journal article, 2020)Vortex interactions behind step cylinders with diameter ratio 2 ≤ D/d ≤ 3 at Reynolds number (ReD) 150 were investigated by directly solving the three-dimensional Navier–Stokes equations. In accordance with the previous ... -
Different topologies of natural vortex dislocations in Mode A wake
Tian, Cai; Shi, Zhaoyu; Jiang, Fengjian; Andersson, Helge Ingolf (Journal article; Peer reviewed, 2022) -
Experimental and numerical investigations on wave profiles and ventilation on a surface-piercing hydrofoil
Solheim Høstmark,; Elisa (Master thesis, 2021)En serie eksperimenter ble gjennomført på to separate overflate-brytende hydrofoiler med Froude tall og angrepsvinkler som hovedparametrene. En bred foil med maksimum tykkelse, t = 120mm, der bølgeprofilene ble undersøkt ... -
Flow Around Curved Tandem Cylinders
Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge Ingolf; Jiang, Fengjian (Peer reviewed; Journal article, 2022)The flow around curved tandem cylinders of equal diameter has been investigated for the first time, by means of direct numerical simulations. A convex configuration was used. The nominal gap ratio was L/D = 3.0 and a ... -
Flow topology in the gap and wake of convex curved tandem cylinders
Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge; Jiang, Fengjian (Journal article; Peer reviewed, 2023)Flow around curved tandem cylinders in the convex configuration has been studied by means of direct numerical simulations, for a Reynolds number of 500 and a nominal gap ratio of 3.0. Spanwise variation of flow regimes, ... -
Forces and torques on a prolate spheroid: low-Reynoldsnumber and attack angle effects
Andersson, Helge Ingolf; Jiang, Fengjian (Journal article; Peer reviewed, 2018)The three-dimensional flow field around a prolate spheroid has been obtained by integration of the full Navier–Stokes equations at Reynolds numbers 0.1, 1.0, and 10. The 6:1 spheroid was embedded in a Cartesian mesh by ... -
How vortex dynamics affects the structural load in step cylinder flow
Tian, Cai; Zhu, Jianxun; Holmedal, Lars Erik; Andersson, Helge; Jiang, Fengjian; Pettersen, Bjørnar (Journal article; Peer reviewed, 2023)The vortex dynamics and the structural load in a step cylinder (consisting of a small, d, and a large, D, cylinder) flow are investigated numerically at Reynolds number (ReD) 150 for diameter ratios D/d=2.0,2.4 and 2.8. ... -
Influences of upstream extensions on flow around a curved cylinder
Jiang, Fengjian; Pettersen, Bjørnar; Andersson, Helge Ingolf (Journal article; Peer reviewed, 2018)In simulations of flow around a concave curved cylinder, i.e. free-stream aligned with the plane of curvature and directed towards the inner face of the curvature, one cannot avoid interactions between the cylinder and the ... -
Low-frequency oscillations in flow past an inclined prolate spheroid
Strandenes, Håkon; Jiang, Fengjian; Pettersen, Bjørnar; Andersson, Helge Ingolf (Journal article; Peer reviewed, 2019)We analyse the forces on a 45∘ inclined 6:1 prolate spheroid at Reynolds number ReD = 8000. In contrast to flow at lower Reynolds numbers previously investigated, we now find a strong oscillatory behaviour in the global ... -
Near-Wake of an Inclined 6:1 Spheroid at Reynolds Number 4000
Strandenes, Håkon; Jiang, Fengjian; Pettersen, Bjørnar; Andersson, Helge Ingolf (Journal article; Peer reviewed, 2019)The flow around a 6:1 prolate spheroid at 45 deg inclination angle and Reynolds number 4000 (based on the minor axis) is described. Despite the fact that the inflow is uniform and steady, the resulting wake is highly ... -
Numerical investigation of 3D flow around a circular cylinder with forced oscillations
Nygård, Jonas (Master thesis, 2023)Sirkulære sylindere blir brukt i ulike maritime anvendelser som rørledninger og stigerør. Flere eksperimenter utført ved Marintek ble gjennomført av K.H. Aronsen på problemet med en sylinder som svinger både i x- og ... -
Numerical Studies of Viscous Flow Around Step Cylinders
Tian, Cai (Doctoral theses at NTNU;2021:122, Doctoral thesis, 2021)A step cylinder consists of a small diameter cylinder (d) attached coaxially to a large diameter cylinder (D). Structures with a similar shape as the step cylinder have been extensively used in many marine engineering ap- ... -
Numerical studies of viscous flow around straight and curved tandem cylinders
Aasland, Tale Egeberg (Doctoral theses at NTNU;2024:81, Doctoral thesis, 2024)The physics of flow around straight and curved cylinders in tandem is investigated by means of direct numerical simulations (DNS), for transitional and turbulent flow regimes. For straight tandem cylinders in the reattachment ... -
Numerisk simulering av en viskøs strømning rundt en krum sylinder i tverrstrøm
Mortensen, Olav Egaas (Master thesis, 2019)Denne masteravhandlingen presenterer numeriske undersøkelser av den tredimensjonale viskøse strømningen rundt en rett sirkulær sylinder og en krum sirkulær sylinder i tverrstrøm. Simuleringer har blitt utarbeidet i ... -
Numerisk Simulering av strømning rundt en kurvet sylinder med varierende diameter
Ramsvik, Emil Severin (Master thesis, 2019)I denne masteroppgaven utforskes strømning rundt en konkav buet sylinder med en endring i diameter. Studien bruker direkte numerisk simulering for å løse Navier-Stokes ligningene uten bruk av turbulensmodellering. Fokuset ... -
Recent Developments and New Results on The Flow Around an Inclined 6:1 Prolate Spheroid
Strandenes, Håkon; Jiang, Fengjian; Pettersen, Bjørnar; Andersson, Helge Ingolf (Chapter, 2017)In the light of new computational resources and improved simulation tools we present new simulations of the flow around an inclined 6:1 prolate spheroid. We present the development of the flow from the symmetric and laminar ... -
Revisiting the reattachment regime: a closer look at tandem cylinder flow at Re=10000
Aasland, Tale Egeberg; Pettersen, Bjørnar; Andersson, Helge Ingolf; Jiang, Fengjian (Peer reviewed; Journal article, 2022)Tandem cylinder flow comprises several different flow regimes. Within the reattachment regime, the development of the gap shear layers is of utmost importance to the flow, but has received little attention so far. Through ... -
State-of-the-Art Review of Vortex-Induced Motions of Floating Offshore Wind Turbine Structures
Yin, Decao; Passano, Elisabeth; Jiang, Fengjian; Lie, Halvor; Wu, Jie; Ye, Naiquan; Sævik, Svein; Leira, Bernt Johan (Peer reviewed; Journal article, 2022)The motivation for this study is the fast development of floating offshore wind energy and the immature methodology and engineering practice related to predictions of vortex-induced motions (VIM). Benefiting from the oil ... -
Three-dimensional wake transition behind an elliptic cylinder near a moving wall
Zhu, Jianxun; Jiang, Fengjian; Holmedal, Lars Erik (Peer reviewed; Journal article, 2021)In this work, the flow over an elliptic cylinder near a moving wall is investigated for Reynolds numbers less than 150. Here, the ratio between the gap (i.e., the distance between the cylinder and the wall) and the length ...