An L2-stable approximation of the Navier-Stokes convection operator for low-order non-conforming finite elements

2010 ◽  
Vol 66 (5) ◽  
pp. 555-580 ◽  
Author(s):  
G. Ansanay-Alex ◽  
F. Babik ◽  
J. C. Latché ◽  
D. Vola
Keyword(s):  
Finite Elements ◽  
Navier Stokes ◽  
Stable Approximation ◽  
Low Order

A Low-Order Model for Predicting Turbocharger Turbine Unsteady Performance

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Teng Cao ◽  
Liping Xu
Keyword(s):  
Power Output ◽  
Three Dimensional ◽  
Pulsating Flow ◽  
Navier Stokes ◽  
Order Model ◽  
Wave Dynamics ◽  
Predicting Performance ◽  
Set Up ◽  
Cfd Method ◽  
Low Order

In this paper, a low-order model for predicting performance of radial turbocharger turbines is presented. The model combines an unsteady quasi-three-dimensional (Q3D) computational fluid dynamics (CFD) method with multiple one-dimensional (1D) meanline impeller solvers. The new model preserves the critical volute geometry features, which is crucial for the accurate prediction of the wave dynamics and retains effects of the rotor inlet circumferential nonuniformity. It also still maintains the desirable properties of being easy to set-up and fast to run. The model has been validated against a experimentally validated full 3D unsteady Reynolds-averaged Navier–Stokes (URANS) solver. The loss model in the meanline model is calibrated by the full 3D RANS solver under the steady flow states. The unsteady turbine performance under different inlet pulsating flow conditions predicted by the model was compared with the results of the full 3D URANS solver. Good agreement between the two was obtained with a speed-up ratio of about 4 orders of magnitude (∼104) for the low-order model. The low-order model was then used to investigate the effect of different pulse wave amplitudes and frequencies on the turbine cycle averaged performance. For the cases tested, it was found that compared with quasi-steady performance, the unsteady effect of the pulsating flow has a relatively small impact on the cycle-averaged turbine power output and the cycle-averaged mass flow capacity, while it has a large influence on the cycle-averaged ideal power output and cycle-averaged efficiency. This is related to the wave dynamics inside the volute, and the detailed mechanisms responsible are discussed in this paper.

Stable and Semistable Low Order Finite Elements for Viscous Flows

1985 ◽  
Vol 22 (3) ◽  
pp. 474-492 ◽  
Author(s):  
J. M. Boland ◽  
R. A. Nicolaides
Keyword(s):  
Finite Elements ◽  
Viscous Flows ◽  
Low Order

Added Mass and Damping for Cylinder Vibrations Within a Confined Fluid Using Deforming Finite Elements

1987 ◽  
Vol 109 (3) ◽  
pp. 283-288 ◽  
Author(s):  
R. Chilukuri
Keyword(s):  
Finite Elements ◽  
Vibration Amplitude ◽  
Stokes Equations ◽  
Outer Cylinder ◽  
Added Mass ◽  
Navier Stokes ◽  
Element Analysis ◽  
Damping Coefficients ◽  
Moving Cylinder ◽  
Fluid Damping

Added mass and fluid damping coefficients for vibrations of an inner cylinder that is enclosed by a concentric outer cylinder are determined by finite element analysis of the unsteady, laminar, incompressible flow in the annulus. Continuously deforming space-time finite elements are used to track the moving cylinder and the changing shape of the space domain. For small cylinder vibration amplitudes, the present results agree well with the work of earlier investigators who solved the linearized Navier-Stokes equations on a fixed mesh. Fluid damping coefficients are shown to increase with vibration amplitude. Added mass coefficients may either increase or decrease with increasing vibration amplitude.

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