Download presentation

Presentation is loading. Please wait.

Published byWilliam Greene Modified over 2 years ago

1
LARGE-EDDY SIMULATION and LAGRANGIAN TRACKING of a DIFFUSER PRECEDED BY A TURBULENT PIPE Sep 07, 2006 Fabio Sbrizzai a, Roberto Verzicco b and Alfredo Soldati a a Università degli studi di Udine: Centro Interdipartimentale di Fluidodinamica e Idraulica Dipartimento di Energetica e Macchine b Politecnico di Bari: Dipartimento di Ingegneria Meccanica e Gestionale Centre of Excellence for Computational Mechanics

2
LARGE-EDDY SIMULATION OF THE FLOW FIELD Flow exits from a turbulent pipe and enters the diffuser. Kelvin-Helmholtz vortex-rings shed periodically at the nozzle. Pairing/merging produces 3D vorticity characterized by different scale structures.

3
NUMERICAL METHODOLOGY Two parallel simulations: Turbulent pipe DNS LES of a large- angle diffuser DNS velocity field interpolated and supplied to LES inlet. Complex shape walls modeled through the immersed- boundaries (Fadlun et al., 2000) L=8 r l=10 r r

4
LAGRANGIAN PARTICLE TRACKING O(10 5 ) particles having diameter of 10, 20, 50 and 100 m with density of 1000 kg/m 3 Tracked using a Lagrangian reference frame. Particles rebound perfectly on the walls. How to model immersed boundaries during particle tracking? BLUE = particles released in the boundary layer RED = particles released in the inner flow

5
PARTICLE REBOUND Particles rebound on a curved 3D wall. curve equation:

6
LOCAL REFERENCE FRAME To properly model particle rebound within Lagrangian tracking, we use a local reference frame X-Y. X-axis is tangent to the curve, Y is perpendicular. Particle bounces back symmetrically with respect to surface normal. X-Y reference frame is rotated with respect to r-z by angle .

7
FRAME ROTATION 1.Calculation of angle : 2.Rotation matrix. Position: XYXY = sin cos cos -sin rzrz = sin cos cos -sin Ux Uy Ur Uz Velocity:

8
PARTICLE REFLECTION = reflection coefficient ( = 1 perfect rebound)

9
FINALLY… Particle coordinates and velocities are rotated back by the inverse (transposed) of the rotation matrix. That’s it!

Similar presentations

Presentation is loading. Please wait....

OK

Turbulent Fluid Flow daVinci [1510].

Turbulent Fluid Flow daVinci [1510].

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on phonetic transcription ipa Ppt on series and parallel circuits lab Download ppt on coordinate geometry for class 9th chemistry Ppt on symbols of french revolution Ppt on adobe photoshop tools Ppt on power system stability studies Detail ppt on filariasis Ppt on employee motivation Ppt on duty roster template Ppt on job evaluation compensable factors