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Large-Eddy Simulation of typical industrial bends In-plane and - PowerPoint PPT Presentation

Products Solutions Services Large-Eddy Simulation of typical industrial bends In-plane and out-of- plane bend at Re =20000 by V. Kumar, B. Kissling*, P. Panathansiou and F. Aydin * Experimental data Slide 1 03/03/2014 V. Kumar Large-Eddy


  1. Products Solutions Services Large-Eddy Simulation of typical industrial bends In-plane and out-of- plane bend at Re =20’000 by V. Kumar, B. Kissling*, P. Panathansiou and F. Aydin * Experimental data Slide 1 03/03/2014 V. Kumar

  2. Large-Eddy Simulation of flows after typical industrial bends E+H Flowtec AG  Endress+Hauser Flowtec is a world leader in industrial flow meters  Flow meters based on the principles  Thermal, magnetic-inductive, vortex, ultrasonic and Coriolis  Production centers in four continents Europe North America Asia Reinach-CH Cernay-Fr Greenwood / USA Suzhou / China Asia S. America Aurangabad / India Itatiba / Brazil Slide 2 03/03/2014 V. Kumar

  3. Large-Eddy Simulation of flows after typical industrial bends Product Portfolio Line sizes from 1 mm to 3000 mm Promass ss 2 Line Display 4 Line Display Pushbutton Touch Control Promag Proso sonic c Flow Prowi wirl rl t-mass ss Slide 3 03/03/2014 V. Kumar

  4. Large-Eddy Simulation of flows after typical industrial bends Where CFD is playing its role?  Optimizing the design of the flow meters  Flow meters can resolve effects of the order of 0.05% to 1%  highly accurate models and high quality grids are required  To investigate installation effects on the flow meters  how does the flow develops after a disturbance  Typical disturbances are bends, diffusors, reducers → It is very important for a turbulence model to accurately model the effects near the wall Slide 4 03/03/2014 V. Kumar

  5. Large-Eddy Simulation of flows after typical industrial bends Bend Simulations Slide 5 03/03/2014 V. Kumar

  6. Large-Eddy Simulation of flows after typical industrial bends Bend configurations investigated In-plane or 90° bend Out-of-plane bend  Fully-developed inlet generated by a periodic pipe simulation  Approx. 40D downstream length in the simulation  LES, Realizable k-eps two-layer, RSM two-layer and SST models tested  Measurements done using clamp-on ultrasonic sensors over the 0 to 360° at different L/D’s downstream the bends. Slide 6 03/03/2014 V. Kumar

  7. Large-Eddy Simulation of flows after typical industrial bends Mesh For the LES simulation:  G rid resolution 𝑠 + ≅ 15, 𝑨 + ≅ 30, 𝜄 + =15; ∆𝑧 + < 1, 𝑇𝑠 < 1.2  Base size => 0.015 D  ∆𝑧 + is estimated from 𝑆𝑓 𝜐 = 0.199 𝑆𝑓 7/8  Approx. 10 Million Cells for both the cases → Mesh variation and boundary layer variations were also carried Slide 7 03/03/2014 V. Kumar

  8. Large-Eddy Simulation of flows after typical industrial bends LES mesh size and effort requirement  Computational effort goes with 𝑶 𝟐.𝟔 or 𝑺𝒇 𝟒.𝟘  10-20 Million cells grids are computationally affordable for LES ca. 2 days wall time with full 16 nodes, L/D~40 Affordable for industry Slide 8 03/03/2014 V. Kumar

  9. Large-Eddy Simulation of flows after typical industrial bends LES Methodology  Ratio of turbulent length scale and grid-size must be controlled  A RANS simulation carried out before starting an LES k 3/2 ∆ 𝑆 𝑀 = ≤ 0.5, 𝑚 𝑢𝑣𝑠𝑐 = 𝑚 𝑢𝑣𝑠𝑐 ε  CFL <1 in 96-99% cells  Second order time- and space (BCD) discretization  WALE Sub-grid model with wall-limiter and Cw =0.544  Simulations are carried until the averaged mean flow does not change anymore  100k time-steps with time-integration started after 20k steps. → Synthetic turbulence at the inlet to avoid laminarization Slide 9 03/03/2014 V. Kumar

  10. Large-Eddy Simulation of flows after typical industrial bends In-Plane Bend Velocity field downstream in-plane bend • Flow development using RKEPS slowest among all • SST shows artifacts close to the bend • RSM is closest to LES • Same grid for LES and RANS Slide 10 03/03/2014 V. Kumar

  11. Large-Eddy Simulation of flows after typical industrial bends Axial and radial velocity profiles • All RANS models predict much slower flow development for the in-plane bend Slide 11 03/03/2014 V. Kumar

  12. Large-Eddy Simulation of flows after typical industrial bends Comparison with measurements • LDA Measurements by Kalpakli and Orlu, Int. J Heat and Fluid Flow 2013 at 0.67D Downstream the 90° bend • Reasonably well agreement between two independent studies Slide 12 03/03/2014 V. Kumar

  13. Large-Eddy Simulation of flows after typical industrial bends Ultrasonic measurements vs Simulations 5D Downstream 30D Downstream • Deviation from mean flow velocity is plotted • LES shows a very good agreement throughout • RSM the best among RANS Slide 13 03/03/2014 V. Kumar

  14. Large-Eddy Simulation of flows after typical industrial bends Out of plane bend at Re =20’000 • RSM gives artifacts • SST results are similar to RSM • Realizable k-epsilon model seems to be best performing • LES predicts different swirl decay than all RANS models Slide 14 03/03/2014 V. Kumar

  15. Large-Eddy Simulation of flows after typical industrial bends Comparison with ultrasonic measurements-I • At 3D downstream • RKEPS-2L is underpredicting the flow distortion • LES is very close to the measurements • Both RSM and SST shows artificial effects → We performed transient RANS as well without much improvement Slide 15 03/03/2014 V. Kumar

  16. Large-Eddy Simulation of flows after typical industrial bends Comparison with ultrasonic measurements-II • At 11 D downstream • RSM model seems to recover further downstream • In LES, swirl seems to be much faster, i.e. tangential stresses are under predicted → We tested various mesh sizes and different subgrid models Slide 16 03/03/2014 V. Kumar

  17. Large-Eddy Simulation of flows after typical industrial bends Conclusions In-plane bend: • Both RSM and LES are well predicting the flow up to 30D downstream • Realizable K-Epsilon model predicts slower decay of disturbances • SST significantly worse than others Out-of-plane bend: • RANS are better predicting the rotational decay • Close to the bend, both RSM and SST are not performing well • LES is predicting very well close to the bend • However further downstream, swirl decay much slower than as predicted by RANS and in experiments • LES models and grid-resolution to be thoroughly investigated for swirling flows Slide 17 03/03/2014 V. Kumar

  18. Large-Eddy Simulation of flows after typical industrial bends Thank you Vortictiy field in 90° bend Slide 18 03/03/2014 V. Kumar

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