4D Data Assimilation for Large Eddy Simulation of High Speed Turbulent Combustion

2015 ◽  
Author(s):  
Hessam Mirgolbabaei ◽  
Conrad Patton ◽  
Thomas Wignall ◽  
Jack R. Edwards ◽  
Tarek Echekki
Keyword(s):  
Data Assimilation ◽  
Large Eddy Simulation ◽  
Turbulent Combustion ◽  
High Speed ◽  
Eddy Simulation ◽  
Large Eddy

RANS and Large Eddy Simulation of Internal Combustion Engine Flows—A Comparative Study

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Xiaofeng Yang ◽  
Saurabh Gupta ◽  
Tang-Wei Kuo ◽  
Venkatesh Gopalakrishnan
Keyword(s):  
Large Eddy Simulation ◽  
High Speed ◽  
Combustion Engine ◽  
Flow Analysis ◽  
Partial Geometry ◽  
Computational Domain ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Rans Simulations

A comparative cold flow analysis between Reynolds-averaged Navier–Stokes (RANS) and large eddy simulation (LES) cycle-averaged velocity and turbulence predictions is carried out for a single cylinder engine with a transparent combustion chamber (TCC) under motored conditions using high-speed particle image velocimetry (PIV) measurements as the reference data. Simulations are done using a commercial computationally fluid dynamics (CFD) code CONVERGE with the implementation of standard k-ε and RNG k-ε turbulent models for RANS and a one-equation eddy viscosity model for LES. The following aspects are analyzed in this study: The effects of computational domain geometry (with or without intake and exhaust plenums) on mean flow and turbulence predictions for both LES and RANS simulations. And comparison of LES versus RANS simulations in terms of their capability to predict mean flow and turbulence. Both RANS and LES full and partial geometry simulations are able to capture the overall mean flow trends qualitatively; but the intake jet structure, velocity magnitudes, turbulence magnitudes, and its distribution are more accurately predicted by LES full geometry simulations. The guideline therefore for CFD engineers is that RANS partial geometry simulations (computationally least expensive) with a RNG k-ε turbulent model and one cycle or more are good enough for capturing overall qualitative flow trends for the engineering applications. However, if one is interested in getting reasonably accurate estimates of velocity magnitudes, flow structures, turbulence magnitudes, and its distribution, they must resort to LES simulations. Furthermore, to get the most accurate turbulence distributions, one must consider running LES full geometry simulations.

Toward Validation of Large Eddy Simulation for Turbulent Combustion

AIAA Journal ◽  
2006 ◽  
Vol 44 (3) ◽  
pp. 418-433 ◽  
Author(s):  
Joseph C. Oefelein ◽  
Robert W. Schefer ◽  
Robert S. Barlow
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Combustion ◽  
Eddy Simulation ◽  
Large Eddy
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