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The feasibility of using a commercial CFD code for large eddy simulation (LES) is investigated. A first test on homogeneous turbulence decay allows a fine-tuning of the eddy viscosity with respect to the numerical features of the code. Then, a flow over forward–backward facing step at Reynolds number Reh ¼ 1:7 105 is computed. The results found show good agreement with the new LDA data of Leclercq et al. . The acoustic source term, recorded from the LES and to be fed into a following acoustic propagation simulation,is found to be largest in the separation from the forward step. The source...
Large Eddy Simulations are performed in a T-junction to analyze the feasibility of wall-functions in accurately predicting the thermal fluctuations acting on the pipe walls. The WALE sub-grid-scale model employed in the LES solver is validated by performing OECD/NEA T-Junction benchmark test-case. In order to reduce the computational costs, Reynolds number scaling is performed while preserving the essential flow features. While the wall-function based simulation showed good agreement with the wall-resolved approach for the bulk velocity and temperature field, the corresponding RMS components...
Unfavorable winds are often found in complex terrain and these complicated flow phenomena such as flow separation and vortex shedding can cause difficulties in siting of wind turbines. This paper uses a DES method to depict the unsteady flows observed in the vicinity of a wind turbine location. A costal site is selected for this study. It has been observed that the variations of wind velocities and wind directions may be large across the rotor area. The large differences in wind velocity and wind direction can cause problems to a wind turbine in operation. The CFD simulations may provide...
Gas-liquid slug flow can exert cyclic forces on pipe bends. A knowledge of the time-varying force and its distribution on the bends is highly desirable in designing the piping and piping support systems. A numerical study has been carried out to obtain an understanding of the slug flow induced forces and develop simulation models for engineering applications. The STAR-OLGA coupling has been applied to achieve a co-simulation of 3-D CFD (Computational Fluid Dynamics) and 1-D pipeline models. In the coupling model a horizontally oriented 90° bend with a diameter of 70 mm is modelled using 3-D...
The performance of a gas diffusion layer comprised of a macro porous and micro porous layer has been studied both experimentally and by numerical simulation. Experimental data at different humidification conditions have been compared to full cell, three-dimensional computational fluid dynamics calculations to validate the physical model of the cell. Local distributions of current density, electrochemical variables, temperature,and gas composition are discussed in detail. Model calculations agree well with experimental data and the solutions with and without the micro porous layer show that...
In this paper parametric analytical studies have been carried out for the geometrical optimization of dump diffusers for modern aero-gas turbine engines. Numerical studies have been carried out using SST K- turbulence model. This code solves SST k- turbulence equations using the coupled second order implicit unsteady formulation. In the numerical study, a fully implicit finite volume scheme of the compressible, Reynolds-Averaged, Navier- Stokes equations is employed. We concluded that the judicious optimization of dump diffusers is needed with respect to its geometric and fluid dynamic...
This paper aims to study numerically the influence of the number of fuel sprays in a single-cylinder diesel engine on mixing and combustion. The CFD simulations are carried out for a heavy-duty diesel engine with an 8 hole injector in the standard configuration. The fuel spray mass-flow rate was obtained from 1D-simulations and has been adjusted according to the number of nozzle holes to keep the total injected fuel mass constant. Two cases concerning the modified mass-flow rate are studied. In the first case the injection time was decreased whereas in the second case the nozzle hole diameter...
A set of through-thickness averaged equations for momentum and strain rate are derived for the problem of axi-symmetric free-surface flow within a spinning cone. The expressions are independent of the choice of constitutive law and can therefore be used for modeling the flow of a variety of materials within an industrial conical centrifuge. By assuming a through-thickness velocity profile the distribution of flow thickness and average velocity over the internal surface of the cone can be obtained. The approach has been validated for thin Newtonian viscous flow by comparison with full three-...

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