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From page 138... ... 138 As discussed in Chapters 1 and 2, one of the critical issues associated with all erosion test devices is that they do not give the same erosion parameters and, therefore, do not lead to the same type of results. To overcome this issue, all tests need to be studied in the same fashion. Read the entire page →
From page 139... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 139 deformations such as those encountered in multiple-ship and floating pier interactions; green water and slamming impact of ships in random waves; vortex-induced motion of offshore platforms; and pier scour, abutment scour, and bridge scour, including overtopping. Both the soil roughness and bed load transport models are incorporated in CHEN4D for the simulation of erosion and accretion of deformable soils. Read the entire page →
From page 140... ... 140 Relationship Between Erodibility and Properties of Soils (2) a surface with 5% roughness to represent coarse sand and gravel. Read the entire page →
From page 141... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 141 on the point of impingement is zero, while the maximum shear stress occurs at a short distance from the center. Figure 99 shows that for soil with a smooth surface (clayey soil) Read the entire page →
From page 142... ... 142 Relationship Between Erodibility and Properties of Soils 6.1.3 HET Simulations CFD numerical simulations were performed for the Wan and Fell (2002) Read the entire page →
From page 143... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 143 velocity (in the hole) Read the entire page →
From page 144... ... 144 Relationship Between Erodibility and Properties of Soils Figure 103. Shear stress distribution through the drilled hole along the length of the sample for both smooth and 5% rough surfaces, considering an average velocity of 2.5 m/s in the hole. Read the entire page →
From page 145... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 145 where rw = density of water (kg/m3) , v = flow velocity (m/s) Read the entire page →
From page 146... ... 146 Relationship Between Erodibility and Properties of Soils Figure 105. Velocity evolution for the smooth case. Read the entire page →
From page 147... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 147 Figure 106. Shear stress distribution on both top surface (which is smooth) Read the entire page →
From page 148... ... 148 Relationship Between Erodibility and Properties of Soils Figure 109. Shear stress evolution captured in six time steps when the flow velocity in the conduit is 1 m/s (from top left to bottom right) Read the entire page →
From page 149... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 149 Figure 110. Shear stress evolution captured in six time steps when the flow velocity in the conduit is 3 m/s (from top left to bottom right) Read the entire page →
From page 150... ... 150 Relationship Between Erodibility and Properties of Soils Figure 111. Shear stress evolution captured in six time steps when the flow velocity in the conduit is 6 m/s (from top left to bottom right) Read the entire page →
From page 151... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 151 shows the schematic diagram of the BET: the jet induces shear stress both at the circular bottom surface and along the side walls in the z-direction. Shear stress results for both regions are presented below for the two aforementioned flow rates. Read the entire page →
From page 152... ... 152 Relationship Between Erodibility and Properties of Soils 90 gpm, 6-inch gap 90 gpm, 3-inch gap 90 gpm, 1-inch gap Figure 113. Shear stress distribution along the side wall surface of the drilled hole with 1-in., 3-in., and 6-in. Read the entire page →
From page 153... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 153 Figure 116 shows an example of the numerical simulations in four different time steps. In this example, the gap between the discharge orifice and the bottom of the borehole is 1 in. Read the entire page →
From page 154... ... 154 Relationship Between Erodibility and Properties of Soils test performed on the same soil sample. Figure 117 shows a flowchart describing the procedure for each numerical simulation. Read the entire page →
From page 155... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 155 6.2.2 Mesh Geometry and Soil–Water Interface For all three erosion tests (JET, HET, and BET) , two-dimensional axisymmetric models were created. Read the entire page →
From page 156... ... Figure 118. Axisymmetric model for the JET. Read the entire page →
From page 157... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 157 wall. The general formulation of the law of the wall (Equation 59) Read the entire page →
From page 158... ... 158 Relationship Between Erodibility and Properties of Soils to ε defined in the Moody diagram shown in Figure 104) Read the entire page →
From page 159... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 159 (1) Read the entire page →
From page 160... ... 160 Relationship Between Erodibility and Properties of Soils soil–water interface. This underestimation was more pronounced when the RH was close to 0 mm (smooth surface) Read the entire page →
From page 161... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 161 STAR-CCM+ Smooth STAR-CCM+ Roughness Height = 0.5 mm STAR-CCM+ Roughness Height = 1 mm STAR-CCM+ Roughness Height = 3 mm Observed Figure 124. Scour depth versus time for observed JET and simulated JET for B-1 (4–6 ft) Read the entire page →
From page 162... ... 162 Relationship Between Erodibility and Properties of Soils 6.2.3.2 EFA's Erosion Function on the HET The approach outlined in Figure 117 was used to compare the results of the EFA with the HET on the same soil samples. The erosion process for two samples (one silt and one clayey sand) Read the entire page →
From page 163... ... Time = 350 s Time = 700 s Time = 1,400 s Figure 127. Example of moving boundary for SH-1 with RH = 0.5 mm. Read the entire page →
From page 164... ... 164 Relationship Between Erodibility and Properties of Soils soil–water interface. This underestimation was even more pronounced when the surface was smoother. Read the entire page →
From page 165... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 165 Figure 129. Results of BET numerical simulation after 20 min using the EFA's erosion function. Read the entire page →
From page 166... ... 166 Relationship Between Erodibility and Properties of Soils (1) Read the entire page →
From page 167... ... Comparison of Selected Soil Erosion Tests by Numerical Simulation 167 Sample Name RH (mm) Final Observed Scour (mm) Read the entire page →

From page 138...

... 138 As discussed in Chapters 1 and 2, one of the critical issues associated with all erosion test devices is that they do not give the same erosion parameters and, therefore, do not lead to the same type of results. To overcome this issue, all tests need to be studied in the same fashion.