5.3 DOWNSTREAM SIDE, WITH FIN
CFD predictions, hexahedralmesh, No fin, 45 degree yaw Upstream side, 0.500 m/s
0.2 0.2
Vector magnitude, m/s
0 0.250.15 -0.2 0.1 0.05 0.35 0.4 -0.4 -0.4 -0.6 -1.6 -1.4 -1.2 -1 y(flow grid) Figure 10, Flow vectors for hexahedral mesh 5.2 DOWNSTREAM SIDE, WITHOUT FIN 0.2
CFD predictions, tetrahedral mesh, No fin, 45 degree yaw Downstreamside, 0.500 m/s
0.2 0 -0.2 -0.4 -0.6
Vector magnitude, m/s
0.5 0.35 0.2
0.1 0.4
0.45 -0.6 -1 -0.8 -0.6 -0.4 y (flow grid) -1 -0.8 -0.6 -0.4 -0.2 y (flow grid) Figure 11, Flow vectors for tetrahedral mesh
6. QUANTITATIVE COMPARISON OF FLOW PATTERNS PREDICTED BY CFD AGAINST MEASURED PIV DATA
CFD predictions, hexahedralmesh, No fin, 45 degree yaw Downstreamside, 0.500 m/s
Vector magnitude, m/s
0 0.5
-0.2 55
-0.4 -0.6 0.25 0.5 0.45 0.15 0.4
A numerical method was developed for comparing measured flow pattern data with the flow patterns predicted using CFD (Molyneux & Bose, 2007). This data compared the 3-dimensional flow vectors measured in experiments with CFD predictions for the same components over a common plane. This section describes the results of
the same analysis applied to the PIV
experiments on the escort tug (Molyneux et al., 2007) with the CFD predictions for the same flow conditions described above.
-1 -0.8 -0.6 -0.4 -0.2 y (flow grid) Figure 12, Flow vectors for hexahedral mesh 0 0.2 0.4
The CFD data was reduced to a plane larger than the area covered by the measurements,
but smaller than the
complete plane within the CFD simulations. Each velocity component (Vx, Vy, Vz) was plotted as a contour over the reduced plane. In the PIV experiments two measurement grids were used. One was a fine grid, based
B-50 ©2008: Royal Institution of Naval Architects 0 0.2 0.4 Figure 14, Flow vectors for hexahedral mesh 0.5 0.5 -0.2 0 0.2 0.4 -0.2 0.1 0.05 0.35 -0.4 0.4 0
Vector magnitude, m/s
0.5 Figure 13, Flow vectors for tetrahedral mesh
CFD predictions, hexahedralmesh Tugwithfin, 45 degree yaw Downstreamside, 0.500 m/s
-0.8 -0.6 -1 -0.8 -0.6 -0.4 y(flow grid) -0.2 0 0.2 0.5 -0.2 0.2 0.3 0.1 0
Vector magnitude, m/s
0.5
CFD predictions, tetrahedralmesh Tugwithfin, 45 degree yaw, Downstreamside, 0.500 m/s
0.5
0.05
0.5
0.05
0.25
0.15
0.25
0.3
0.3
0.45
Z
Z
Z
0.25
Z
Z
0.45
0.35
0.1
0.2
0.1
0.1 0.2 0.4
0.4
0.2
0.45
0.5
0.45
0.35
0.2
0.4
0.45
0.3
0.5
0.35
0.55
0.35
0.05
0.2
0.4
0.45
0.3
0.5 0.55
0.5
0.5 0.1
0.3
0.4
0.5
0.15
0.3 0.2
0.55
0.25
0.5
0.3
0.35
0.55
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