A numerical method for large-eddy simulation in complex geometries

2003 ◽  
pp. 23-30
Author(s):  
K. Mahesh ◽  
G. Constantinescu ◽  
P. Moin
Keyword(s):  
Large Eddy Simulation ◽  
Numerical Method ◽  
Complex Geometries ◽  
Eddy Simulation ◽  
Large Eddy

Large Eddy Simulation on the Unsteady Aerodynamics of a Heavy Duty Truck in Wind Gust

2011 ◽  
Author(s):  
Makoto Tsubokura ◽  
Prasanjit Das ◽  
Tomofuyu Matsuuki ◽  
Takuji Nakashima
Keyword(s):  
Large Eddy Simulation ◽  
Numerical Method ◽  
Unsteady Aerodynamics ◽  
Static Condition ◽  
Wind Tunnels ◽  
Wind Gust ◽  
Heavy Duty ◽  
Heavy Duty Truck ◽  
Eddy Simulation ◽  
Large Eddy

Unsteady aerodynamic forces acting on a full-scale heavy duty truck were investigated using a large-eddy simulation technique. The numerical method adopted was first validated on a static condition measured at the DNW German-Dutch wind tunnels. After the correction of the blockage ratio in the wind tunnel, the drag coefficient obtained by our numerical method showed good agreement with the experimental data within the errors of less than 5%. Effect of an air deflector mounted on the top of a cabin was also discussed. Then the method was applied to non-stationary conditions in which the truck was subjected to ambient perturbation of approaching flow. The perturbation of the flow is a model of atmospheric turbulence and sinusoidal crosswind velocity profiles were imposed on the uniform incoming flow with its wavelength comparable to the vehicle length. As a result, it was confirmed that when the wavelength of the crosswind is close to the vehicle length, averaged drag increases by more than 10% and down-force decreases by about 60%, compared with the case without perturbation.

Application of a Dynamic Global-Coefficient Subgrid-Scale Model for Large-Eddy Simulation in Complex Geometries

2007 ◽  
Author(s):  
Donghyun You ◽  
Parviz Moin
Keyword(s):  
Large Eddy Simulation ◽  
Eddy Viscosity ◽  
Viscosity Model ◽  
Scale Model ◽  
Complex Geometries ◽  
Subgrid Scale ◽  
Eddy Simulation ◽  
Eddy Viscosity Model ◽  
Large Eddy ◽  
Model Coefficient

The application of a dynamic global-coefficient subgrid-scale eddy-viscosity model for large-eddy simulation in complex geometries is presented. The model employs a dynamic procedure for closure of the subgrid-scale eddy-viscosity model developed by Vreman [Phys. Fluids 16, 3670 (2004)]. The model coefficient which is globally constant in space but varies in time is dynamically determined assuming the “global equilibrium” between the subgrid-scale dissipation and the viscous dissipation of which utilization was proposed by Park et al. [Phys. Fluids 18, 125109 (2006)]. Like the Vreman’s model with a fixed coefficient and the dynamic-coefficient model of Park et al., the present model predicts zero eddy-viscosity in regions where the vanishing eddy viscosity is theoretically expected. The present dynamic model is especially suitable for large-eddy simulation in complex geometries since it does not require any ad hoc spatial and temporal averaging or clipping of the model coefficient for numerical stabilization and requires only a single-level test filter.

scholarly journals Jet Noise in Airframe Integration and Shielding

2020 ◽  
Vol 10 (2) ◽  
pp. 511
Author(s):  
Saman Salehian ◽  
Reda Mankbadi
Keyword(s):  
Experimental Data ◽  
Large Eddy Simulation ◽  
Jet Noise ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Complex Geometries ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes

This paper reviews and presents new results on the effect of airframe integration and shielding on jet noise. Available experimental data on integration effects are analyzed. The available options for the computation of jet noise are discussed, and a practical numerical approach for the present topic is recommended. Here, it is demonstrated how a hybrid large eddy simulation—unsteady Reynolds-averaged Navier-Stokes approach can be implemented to simulate the effect of shielding on radiated jet noise. This approach provides results consistent with the experiment and suggests a framework for studying more complex geometries involving airframe integration effects.

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