Direct Numerical Simulation of Spatial Transition to Turbulence Using Fourth-Order Vertical Velocity Second-Order Vertical Vorticity Formulation

2002 ◽  
Vol 180 (1) ◽  
pp. 200-228 ◽  
Author(s):  
Kiran Bhaganagar ◽  
Dietmar Rempfer ◽  
John Lumley
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Fourth Order ◽  
Vertical Velocity ◽  
Second Order ◽  
Transition To Turbulence ◽  
Vertical Vorticity ◽  
Spatial Transition

Direct numerical simulation of the flow over a sphere at Re = 3700

2011 ◽  
Vol 679 ◽  
pp. 263-287 ◽  
Author(s):  
IVETTE RODRIGUEZ ◽  
RICARD BORELL ◽  
ORIOL LEHMKUHL ◽  
CARLOS D. PEREZ SEGARRA ◽  
ASSENSI OLIVA
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Shear Layer ◽  
Large Scale ◽  
Power Spectra ◽  
Numerical Data ◽  
Transition To Turbulence ◽  
Stream Velocity ◽  
Sphere Diameter ◽  
Mean Flow

The direct numerical simulation of the flow over a sphere is performed. The computations are carried out in the sub-critical regime at Re = 3700 (based on the free-stream velocity and the sphere diameter). A parallel unstructured symmetry-preserving formulation is used for simulating the flow. At this Reynolds number, flow separates laminarly near the equator of the sphere and transition to turbulence occurs in the separated shear layer. The vortices formed are shed at a large-scale frequency, St = 0.215, and at random azimuthal locations in the shear layer, giving a helical-like appearance to the wake. The main features of the flow including the power spectra of a set of selected monitoring probes at different positions in the wake of the sphere are described and discussed in detail. In addition, a large number of turbulence statistics are computed and compared with previous experimental and numerical data at comparable Reynolds numbers. Particular attention is devoted to assessing the prediction of the mean flow parameters, such as wall-pressure distribution, skin friction, drag coefficient, among others, in order to provide reliable data for testing and developing statistical turbulence models. In addition to the presented results, the capability of the methodology used on unstructured grids for accurately solving flows in complex geometries is also pointed out.

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