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Figure 2.33 Comparison of CFD and PIV velocity contour under the condition of 0.3D bed elevation and 0.71 fps for 9 inch water depth (velocity: 21.6 cm/s) 2.3.1.2. Model accuracy analysis When the data from two different methods are compared (for example, CFD and PIV), the difference can somewhat vary through the cross section. The root-mean-square-deviation (RMSD) is used in this study to provide a single measure of difference for the comparison of a large number of data points in an entire cross section. RMSD is defined as: TRACC/TFHRC Y2Q2 Page 49
RMSD area area ( V1 V2 ) n area 2 2.14 where V 1 and V 2 are velocity magnitudes from two different approaches. The RMSD tends to be greater for greater average velocity. A relative percentage error is used as a normalized measure of the error. It is defined as: Relative error (%)=100 x RMSD/V average 2.15 Based on the 5mm-by-5mm interpolated grid data, the RMSD are calculated for each flow and bed condition. RMSD and relative error vary from 2.182 cm/s to 9.515 cm/s and from 9.48% to 28.38%, respectively. The RMSD number and relative error for each situation are listed in Table 2.3: Table 2.3 RMSD and relative error between CFD and experimental results for different conditions Bed elevation(inch) 0 5.4 Velocity (fps) 0.71 1.1 0.71 1.1 Water depth (inch) PIV and CFD RMSD(cm/s) Relative error(%) ADV and CFD RMSD(cm/s) Relative error(%) 4.5 5.185 23.96 2.545 11.76 6 4.337 20.04 4.043 18.68 9 4.317 19.95 4.116 19.02 4.5 9.515 28.38 7.838 23.38 6 6.227 18.57 3.177 9.48 9 7.316 21.82 6.241 18.61 4.5 2.654 12.26 2.572 11.89 6 4.520 20.89 2.327 10.75 9 2.298 10.62 2.182 10.08 4.5 3.466 10.34 3.828 11.42 6 4.863 14.50 6.300 18.79 TRACC/TFHRC Y2Q2 Page 50
Page 1 and 2: ANL/ESD/12-27 Energy Systems Divisi
Page 3 and 4: ANL/ESD/12-27 Computational Mechani
Page 5 and 6: List of Figures Figure 2.1: Bridge
Page 7 and 8: Figure 2.35: Two different transiti
Page 9 and 10: 1. Introduction and Objectives The
Page 11 and 12: 2. Computational Fluid Dynamics for
Page 13 and 14: flat surface assumption is good exc
Page 15 and 16: conditions from Example 1 defined i
Page 17 and 18: scour rate is initially highest nea
Page 19 and 20: Figure 2.6 Dividing streamline posi
Page 21 and 22: 2.1.3. Resolving Issues of the Seco
Page 23 and 24: educe the rate of increase for y wh
Page 25 and 26: Design Scour Depth 0.400 0.350 0.30
Page 27 and 28: extend the impact of the findings t
Page 29 and 30: Table 2.2 Contour plots comparing C
Page 31 and 32: Figure 2.14 Comparison of CFD and P
Page 37 and 38: consistent with the lab test setup,
Page 49: Figure 2.32 Comparison of CFD and P
Page 53 and 54: 2. Marian Muste, Hao-Che Ho, Daniel
Page 55 and 56: Honeycomb Streamline Trumpet Unifor
Page 57 and 58: (a) Streamline trumpet transition c
Page 59 and 60: 2.6. Training and Technology Transf
Page 61: Figure 2.40: Announcement for CFD t

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