Numerical prediction of turbulent flows using Reynolds-averaged Navier-Stokes and large-eddy simulation with uncertain inflow conditions

2012 ◽  
Vol 72 (3) ◽  
pp. 341-358 ◽  
Author(s):  
Pietro Marco Congedo ◽  
Cedric Duprat ◽  
Guillaume Balarac ◽  
Christophe Corre
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flows ◽  
Numerical Prediction ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes ◽  
Inflow Conditions

A modified blending function for zonal hybrid Reynolds-averaged Navier—Stokes/large-eddy simulation methodology

2009 ◽  
Vol 223 (8) ◽  
pp. 1067-1081 ◽  
Author(s):  
M B Sun ◽  
J H Liang ◽  
Z G Wang
Keyword(s):  
Boundary Layer ◽  
Supersonic Flow ◽  
Large Eddy Simulation ◽  
Turbulent Flows ◽  
Navier Stokes ◽  
Empirical Constant ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes ◽  
Blending Function

A modified blending function for zonal hybrid Reynolds averaged Navier—Stokes/large eddy simulation (RANS/LES) methodology was developed using an empirical analogy from Menter k—ω shear stress transport (SST) turbulent model (Menter, 1994) to predict complex turbulent flows. Tests of slot jet in supersonic flow and supersonic flow over compression—expansion ramp was conducted and prediction of separations was well improved when certain model constant was forced on the traditional blending function (Baurle et al., 2003). Analysis based on calculations of flat plate boundary layer demonstrated that an efficient empirical constant could be used in blending function and boundary layer could be well calculated without heavy contamination of RANS on wake region. Validation of the modified zonal hybrid RANS/LES approach for slot jet in supersonic flow, supersonic flow over compression—expansion ramp, supersonic flow over backward facing step, and supersonic cavity flow was conducted. The simulated results showed that the modified blending function performs well on complex turbulent flows. Deficiencies of traditional hybrid zonal RANS/LES method in over-prediction of separations associated with adverse pressure gradient flows were favourably improved.

Hybrid Large Eddy Simulation/Reynolds-Averaged Navier–Stokes Analysis of a Premixed Ethylene-Fueled Dual-Mode Scramjet Combustor

AIAA Journal ◽  
2021 ◽  
pp. 1-17
Author(s):  
Tanner B. Nielsen ◽  
Jack R. Edwards ◽  
Harsha K. Chelliah ◽  
Damien Lieber ◽  
Clayton Geipel ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Navier Stokes ◽  
Dual Mode ◽  
Eddy Simulation ◽  
Scramjet Combustor ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes

scholarly journals Investigation of flow separation in a centrifugal pump impeller based on improved delayed detached eddy simulation method

2019 ◽  
Vol 11 (12) ◽  
pp. 168781401989783
Author(s):  
Yun Ren ◽  
Zuchao Zhu ◽  
Denghao Wu ◽  
Xiaojun Li ◽  
Lanfang Jiang
Keyword(s):  
Large Eddy Simulation ◽  
Centrifugal Pump ◽  
Flow Separation ◽  
Hybrid Algorithm ◽  
Internal Flow ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Reynolds Averaged Navier Stokes ◽  
Vorticity Flux

The mechanism of flow separation in the impeller of a centrifugal pump with a low specific speed was explored by experimental, numerical, and theoretical methods. A novel delayed Reynolds-averaged Navier–Stokes/large eddy simulation hybrid algorithm combined with a rotation and curvature correction method was developed to calculate the inner flow field of the original pump for the large friction loss in the centrifugal impeller, high adverse pressure gradient, and large blade curvature. Boundary vorticity flux theory was introduced for internal flow diagnosis, and the relative velocity vector near the surface of the blade and the distribution of the dimensionless pressure coefficient was analyzed. The validity of the numerical method was verified, and the location of the backflow area and its flow features were determined. Finally, based on flow diagnosis, the geometric parameters influencing the flow state of the impeller were specifically adjusted to obtain a new design impeller. The results showed that the distribution of the boundary vorticity flux peak values, the skin friction streamline, and near-wall relative velocities improved significantly after the design change. In addition, the flow separation was delayed, the force applied on the blade was improved, the head under the part-load condition was improved, and the hydraulic efficiency was improved over the global flow ranges. It was demonstrated that the delayed Reynolds-averaged Navier–Stokes/large eddy simulation hybrid algorithm was capable to capture the separation flow in a centrifugal pump, and the boundary vorticity flux theory was suitable for the internal flow diagnosis of centrifugal pump.

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