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- Fureby, C., et al.
(författare)
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Incompressible wall-bounded flows
- 2007
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Almost all flows of practical interest are turbulent, and thus the simulation of turbulent flow and its diversity of flow characteristics remains one of the most challenging areas in the field of classical physics. In many situations the fluid can be considered incompressible; that is, its density is virtually constant in the frame of reference, moving locally with the fluid, but density gradients may be passively convected with the flow. Examples of such flows of engineering importance are as follows: external flows, such as those around cars, ships, buildings, chimneys, masts, and suspension bridges; and internal flows, such as those in intake manifolds, cooling and ventilation systems, combustion engines, and applications from the areas of biomedicine, the process industry, the food industry, and so on. In contrast to free flows (ideally considered as homogeneous and isotropic), wall-bounded flows are characterized by much less universal properties than free flows and are thus even more challenging to study. The main reason for this is that, as the Reynolds number increases, and the thickness of the viscous sublayer decreases, the number of grid points required to resolve the near-wall flow increases. The two basic ways of computing turbulent flows have traditionally been direct numerical simulation (DNS) and Reynolds-averaged NavierâStokes (RANS) modeling. In the former the time-dependent NavierâStokes equations (NSE) are solved numerically, essentially without approximations. In the latter, only time scales longer than those of the turbulent motion are computed, and the effect of the turbulent velocity fluctuations is modeled with a turbulence model.
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- Svennberg, U., et al.
(författare)
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Large eddy simulation of the flow past the DTMB5415 surface combatant hull with and without bilge keels
- 2011
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Ingår i: MARINE 2011 - Computational Methods in Marine Engineering IV (4th International Conference on Computational Methods in Marine Engineering, MARINE 2011; Lisbon; 28-30 September 2011). - 9788489925793 ; , s. 605-616
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Konferensbidrag (refereegranskat)abstract
- The flow around the DTMB5415 surface combatant hull with and without bilge keels is studied numerically by the use of a Large Eddy Simulation (LES) method. The main purpose for bilge keels is to reduce roll motions when operating in ocean waves. The flow resistance should at the same time be affected as little as possible. The computations presented here are for straight course in calm water conditions and show only a small change in the wake of the hull and there by a minimal effect on the resistance. The computations are made as a preparatory step before investigating other conditions, such as yaw angle.
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- Zhang, B. L., et al.
(författare)
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CFD Modeling of Propeller Tip Vortex over Large Distances
- 2014
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Ingår i: International Journal of Offshore and Polar Engineering. - 1053-5381. ; 24:3, s. 181-183
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a numerical study has been conducted to investigate the evolution of a ship propeller tip vortex over a large distance by using Reynolds-averaged Navier-Stokes (RANS) CFD method. In order to reduce numerical dissipation in tracking the tip vortex, a unique hybrid mesh structure was designed, and a vorticity confinement method was also introduced to further enhance the high resolution of the tip vortex.
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