FLOW AROUND A CYLINDER - istiarto

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– 3.12 – The spatial evolution of the v-velocity component in the planes � = 45°, 90°, and 135°, is displayed in Fig. 3.4. Shown on the left are the scalar values of the v velocity, normalized by the velocity in the approach flow, v U� . Shown on the right are the direction (in degrees) of the local velocity vector, V h�u,v �, with respect to the plane of symmetry, such as � � arctan�v u� with –90 ≤ � [°] ≤ 90. The negative values (indicated by the dashed contour lines) denote flow being deflected away from the plane of symmetry. � In the plane � = 45°, outside the scour hole the v-velocity component remains negligible, implying that the flow is unaltered either by the cylinder or the scour hole. Beginning at r = 35 [cm], it starts to show negative values (the flow deviates away from the plane of symmetry) and vice versa inside the scour hole. Approaching the cylinder, the negative deviation grows stronger in magnitude, v U � ≈ 0.35, in direction, � ≈ –20 [°], and in area, z ≥ –11 [cm] (see Fig. 3.4a,b). Inside the scour hole, a weak flow, v U � ≈ 0.1 to 0.15, deviates strongly, � ≈ 80 [°], towards the plane of symmetry. � In the plane � = 90°, a weak flow deviation, v U � ≈ ±0.1, is observed away from the cylinder at the upper layer, z > 0, and towards the cylinder inside the scour hole (see Fig. 3.4c,d). A small area, confined near the bed, of negative deviation is noticed. In the rest of the scour hole, r > 30 [cm], the flow is not deviated at all. Compared to the measurements on the flat channel bed (Yulistiyanto, 1997), this flow deviation is much less pronounced; the scour hole hinders the cylinder-induced deviating flow from developing. � In the plane � = 135°, a weak flow deviation is observed; although the maximum value is v U � ≈ 0.2, but it is largely around v U � ≈ 0.1. The deviation here is very much similar to that in the plane � = 90°. From the above observation on the transverse velocity component, it can be concluded that influence of the cylinder and the scour hole in deviating horizontally the approach flow is limited inside the scour hole and close to the cylinder. Outside the scour hole, the horizontal flow-direction remains the same as that of the far-field approach flow. This is supported further by the vector plots of the horizontal velocity, V h�u,v �, around the cylinder at different elevations z depicted in Fig. 3.5. Fig. 3.5 also reveals the horizontal component of a rotating flow inside the scour hole; at z = –10 [cm] a clockwise rotating flow is noticeable on the side of the cylinder, 0° < � ≤ 105°, with a weaker counter-clockwise one next to it (see Fig. 3.5c). Deeper inside the scour hole, z = –15 [cm], this structure remains but has become very weak (see Fig. 3.5d). Downstream, � > 90°, and close to the cylinder, the flow is accelerated and directed towards the wake behind the cylinder (see Fig. 3.5c,d). Immediately behind the cylinder, the flow meets the one coming from the other side of the symmetry plane; both together form an upward flow.�
– 3.13 – Fig. 3.4 Contours of the measured transverse velocity, v U � , (on the left) and of the angles formed by the transverse velocity and the longitudinal velocity, arctan v u � � in degrees, (on the right)
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FLOW AROUND A CYLINDER IN A SCOURED
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- iii - Flow around a Cylinder in a
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- v - Écoulement à Surface Libre
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- vii - Acknowledgements I wish to
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- ix - Table of Contents Abstract i
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- xi - 4.4 Pressure-velocity coupli
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Chapter 1 - 1.i - 1 Introduction 1.
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1 Introduction 1.1 Flow around a cy
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- 1.3 - pitot tubes. Ahmed and Raja
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Chapter 2 - 2.i - 2 Flow Measuremen
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2 Flow Measurements Abstract - 2.1
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2.1 Measurement design - 2.3 - The
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- 2.5 - The water circuit is a clos
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- 2.7 - Consider a target ―i‖ m
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- 2.9 - Obtaining the velocity comp
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- 2.11 - Fig. 2.4 Cartesian and cyl
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- 2.13 - transducer were used, a fo
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- 2.15 - typically needed for this
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- 2.17 - 2.3.3 Comparison to other
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- 2.19 - Fig. 2.7 Scour hole geomet
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- 2.21 - Fig. 2.8 Distributions of
Page 43 and 44: u ��u �� u� � Du exp�
Page 45 and 46: - 2.25 - �o , and accordingly the
Page 47 and 48: - 2.27 - Measurements in zone A. Th
Page 49 and 50: - 2.29 - and 0.3 u �� u ��
Page 51 and 52: - 2.31 - Fig. 2.12b Cont’d.
Page 53 and 54: - 2.33 - Fig. 2.12d Cont’d.
Page 55 and 56: 2.5.4 Measurements in the plane �
Page 61 and 62: - 2.41 - the solid boundary of the
Page 67 and 68: - 2.47 - Turbulence intensities in
Page 69 and 70: - 2.49 - Fig. 2.15a Vertical distri
Page 71 and 72: - 2.51 - Fig. 2.15c Cont’d.
Page 73 and 74: - 2.53 - Reynolds stresses in the p
Page 75 and 76: - 2.55 - Fig. 2.16c Cont’d.
Page 77 and 78: 2.6 Summary and conclusions - 2.57
Page 79 and 80: - 2.59 - Rolland, T. (1994). Develo
Page 81 and 82: Chapter 3 - 3.i - 3 Elaboration of
Page 83 and 84: - 3.1 - 3 Elaboration of the measur
Page 85 and 86: 3.1 Introduction - 3.3 - Presented
Page 87 and 88: - 3.5 - Fig. 3.1 Measured velocity
Page 89 and 90: 3.2.2 Flow pattern around the cylin
Page 91 and 92: - 3.9 - Fig. 3.2 Cont’d.
Page 93: Flow in the plane � = 45° and 90
Page 97 and 98: 3.2.4 Vertical velocity (downward f
Page 99 and 100: - 3.17 - flow may undergo a rotatin
Page 103 and 104: - 3.21 - A similar observation, in
Page 105 and 106: - 3.23 - Fig. 3.9 Measured turbulen
Page 107 and 108: The following is to be observed: -
Page 111 and 112: - 3.29 - 3.4 Bed shear-stresses alo
Page 113 and 114: x [cm] - 3.31 - Table 3.1 Estimated
Page 115 and 116: - 3.33 - Fig. 3.12 Estimated bed sh
Page 117 and 118: - 3.35 - (see Fig. 3.10 and Fig. 3.
Page 119 and 120: - 3.37 - Fig. 3.14 Axonometric pres
Page 121 and 122: - 3.39 - U, U∞ [m/s] sectional av
Page 123 and 124: Chapter 4 - 4.i - 4 Numerical Model
Page 125 and 126: - 4.1 - 4 Numerical Model Developme
Page 127 and 128: �u �t �v �t �w �t �
Page 129 and 130: - 4.5 - The volume integrals of the
Page 131 and 132: - 4.7 - Fig. 4.1 Overall iterative
Page 133 and 134: - 4.9 - increase the computer stora
Page 135 and 136: - 4.11 - �� 1 ��
Page 137 and 138: - 4.13 - convective transport throu
Page 139 and 140: - 4.15 - n,��1 during a time st
Page 141 and 142: � for 0 � Pe e � q eL PE �
Page 143 and 144: 4.3.8 Source terms - 4.19 - The sou
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2D � � � x �� b 2D �
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- 4.23 - b T � V P �t � n P
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- 4.25 - �� u ��1 � c i
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- 4.27 - Next, we need to define th
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4.5 Boundary conditions 4.5.1 Bound
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- 4.31 - The above relation holds a
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- 4.33 - � extrapolate all variab
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G � � t 2 �V t - 4.35 - 2 �
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with � �� nt,b � ��
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- 4.39 - boundary node B are then a
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- 4.41 - Wall function for the �
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k and � equations - 4.43 - � se
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�� z-momentum: - 4.45 - ��1
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- 4.47 - � reconstruct the mesh,
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- 4.49 - Fig. 4.13 The structure of
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- 4.51 - ��
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4.7 Summary - 4.53 - Development of
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- 4.55 - B, �B [-] constant and w
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- 4.57 - �, � 1 , � p [-] und
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Chapter 5 - 5.i - 5 Numerical Simul
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5 Numerical Simulation Abstract - 5
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5.2 Experimental data - 5.3 - 5.2.1
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- 5.5 - computational nodes. The ot
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- 5.7 - (i) Yulistiyanto data (ii)
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- 5.9 - ( p � � 1 [mm]), but th
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- 5.11 - Fig. 5.4 Model test result
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- 5.13 - within a greater number of
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- 5.15 - Fig. 5.6 Computational his
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- 5.17 - 5.5 Simulation of flow aro
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- 5.19 - Fig. 5.9 Definition sketch
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- 5.21 - Fig. 5.10 Computed (lines)
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- 5.23 - Fig. 5.11 Computed and mea
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- 5.25 - 1.2U ∞ of the measuremen
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Water-surface profile - 5.27 - The
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- 5.29 - using a Joukowski transfor
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- 5.31 - 5.6.3 Results of the simul
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Velocity fields around the cylinder
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- 5.35 - Fig. 5.18 Computed and mea
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- 5.37 - than the measured one. The
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- 5.39 - Production and dissipation
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- 5.41 - Production of turbulent ki
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- 5.43 - If the above approach were
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- 5.45 - and surface profiles (see
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- 5.47 - Fig. 5.24 Surface boundary
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- 5.49 - S [m 2 ] surface area. So,
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Chapter 6 - 6.i - 6 Summary and Con
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- 6.1 - 6 Summary and Conclusions 6
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- 6.3 - The spatial distributions o
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- 6.5 - � Laboratory measurements
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- 6.7 - Fig. 6.1 Measured and compu
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IDENTITE - 7.1 - Curriculum Vitæ N
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- iii - Appendices Appendix A: Expe
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A Experimental Data - A.1 - The exp
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B Numerical Model B.1 Program struc
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- B.3 -
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B.2 Input data file - B.5 - The inp
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- B.7 - #31 imon1, jmon1, kmon1 thr
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BLO for blocked cells, INL for inle
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FLOW AROUND A CYLINDER - istiarto

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