Effect Of Intersection Angle Research Articles

Effect of geometry and hydraulic parameters on the bed morphology in a confluence using numerical approach

The confluence of rivers is an important phenomenon that is really vital for irrigation and water transmission networks. Investigation on bed morphology at the junction of two streams is of great importance. Flow complexity at confluences, as well as being at risks of rising water levels and flooding, interfering with the use of bridges, filling the inlets of the ponds and reducing the efficiency of water transport are resulted by this phenomenon. The purpose of this research is to investigate the effect of geometric and hydraulic parameters, such as junction angle, width ratio of two intersected canals, and Froude number on the bed morphology at intersection, using SSIIM2. Validation of the results of numerical model in terms of hydraulic and morphology parameters indicated good correlations coefficients of 0.9 and 0.68, respectively. In the next step, the effect of intersection angle (45, 60, 75, 90 and 105 degrees) on the scour depth was investigated. By decreasing the junction angle from 105° to 45°, the maximum scour depth reduced to about 96% and the scour hole dimensions were smaller and moved toward the confluence shore. Furthermore, the results showed that by increasing the width ratio from 0.5 to 1, and also, decreasing the Froude number ratio of tributary to main channel from 3 to 0.68, maximum scour depth decreased by 25% and 30%, respectively.

Effects of fracture intersection on the hydraulic properties of 3D crossed rough-walled fractures

Characterization of hydraulic properties of crossed fractures is a key issue in understanding flow behavior of rock masses with complex fracture networks, which is of primary importance for many geoengineering practices. The effects of fracture intersection on fluid flow through 3D crossed rough-walled fractures in a linear flow regime were investigated by numerical simulations. A self-developed finite volume code was employed to solve the Navier–Stokes equation in 3D crossed fracture models. Different synthetic fractures were generated based on the data collected from three natural fracture surfaces. A series of numerical models were established by intersecting the different generations of the synthetic fractures to study the effect of surface roughness, intersection angle, intersection length, and scale on fluid flow through crossed rough-walled fractures. To evaluate the intersection effects, the effective transmissivity of the fracture segments, Teff, which is defined as the transmissivity affected by fracture intersection, was compared with the actual transmissivity of the fracture segments, Ta. The results showed that the ratio of Teff/Ta fluctuates more severely for the models with rougher fracture surfaces due to the formation of more complex geometry at fracture intersection. The ratio tends to reach a converged magnitude at large intersection lengths but with a wider ranges of variation for the models with rougher fracture surfaces. The results also showed that beside the complex geometry of intersection, the difference in the ratio of the mean aperture of the intersection facet to the actual hydraulic aperture of the corresponding fracture segment between different fracture segments may have an even more significant impact on the fluid flow in crossed fractures. The intersection angle affects the fluid flow through crossed fractures by altering the geometrical characteristics of the intersection in a heterogeneous manner, which stems from random nature of fracture surface roughness. The effects of intersection angle become negligible at large intersection lengths. The simulation results suggest one of the conditions to ignore the intersection effects on flow behavior of large-scale rough-walled fracture networks when flow is in a linear regime. Accordingly, all the fracture lengths in the fracture network should be larger than REV size of the fractures.

Effect of Intersection Angle and Wettability on Droplet Generation in Microfluidic Flow-Focusing Device

Abstract This article investigates the dynamics of droplet generation process in a microfluidic flow-focusing device under the effect of geometry altered by the intersection angle (φ), which the flanking inlets make with central inlet and wall wettability quantified by the contact angle (θ) using volume of fluid (VOF) model. These parameters have been found to alter the droplet shape and size greatly. The effect of intersection angles has been examined for φ = 15 deg, 30 deg, 45 deg, 60 deg, 90 deg, and 120 deg for generating size-controlled droplets. It was predicted that the diameter of droplet increased with the increase in intersection angle (φ = 15 deg, 30 deg, 45 deg, 60 deg, 90 deg, and 120 deg) and the maximum diameter has been generated at φ = 90. In addition, the wetting characteristics (hydrophilic to hydrophobic) have been studied numerically in detail by changing the contact angle of the dispersed phase with the channel wall ranging from 90 deg to 180 deg. It was indicated that the droplets of rectangular shape are formed in hydrophilic channel by completely wetting the wall when θ ≤ 90 deg. They transform their shape to slightly oval form with the increase in contact angle and start acquiring spherical shape when the channel becomes hydrophobic. Furthermore, Parameters such as dimensionless droplet diameter, droplet shape, and droplet breakup time have also been investigated extensively for flowrate ratios Q = 0.125, 0.25, 0.5, and 1, in order to optimize the microfluidic device.

The Effect of Intersection Angle on the Failure Mechanism of Utility Tunnel

Planning utility tunnel network in the area with geological disasters poses serious concerns, especial for the utility tunnel built in the ground fissures developed cities. Many prevention and control measures have been taken when the utility tunnel crossed the ground fissures, such as finding the right intersection angle when planning the utility tunnel. In order to study the effect of intersection angle for utility tunnel when crossing ground fissures, this paper compares outcomes when the utility tunnel crosses ground fissures with different intersection angle through numerical simulation method. Because actually the intersection angle of utility tunnel and ground fissures is varied, in order to make stress‐strain relationship of the model more realistic, a trilinear mode of reinforcing bar stress‐strain relationship was established, and the material property of utility tunnel and soil were assigned to concrete damaged plasticity and Mohr‐Coulomb plasticity, respectively. The simulation result shows that the axial tension stress and vertical shear stress of utility tunnel are increased with the increasing of intersection angle, but displacement and shear stress of utility tunnel in horizontal direction are increased with the decreasing of intersection angle. The variation of intersection angle of utility tunnel and ground fissures cannot significantly reduce the damage of utility tunnel. The vertical displacement of utility tunnel does not vary with intersection angle. Finally, this paper suggests that the strengthening length of utility tunnel should not be less than 50 meters (10 times the height of utility tunnel) on both sides of the ground fissures no matter the variation of intersection angle.

A Numerical Study on the Crack Development Behavior of Rock-Like Material Containing Two Intersecting Flaws

It is quite often that rocks contain intersecting cracks. Therefore, crack behavior cannot be completely studied by only considering several isolated, single flaws. To investigate the crack behavior of rock or rock-like material containing intersecting flaws under uniaxial loading, numerical simulations were carried out using parallel bonded-particle models containing two intersecting flaws with different inclination angles (varying β) and different intersection angles (varying αα). The crack propagation processes are analyzed and two typical patterns of linkage are observed between two intersecting flaws: (1) One-tip-linkage that contains three subtypes: Coalescence position near the tip; coalescence position at the flaw, but far away from the tip; coalescence position outside the flaw at a certain distance from the tip; and (2) two-tip-linkage with two subtypes: Straight linkage and arc linkage. The geometries of flaws influence the coalescence type. Moreover, the effects of intersection angle α and inclination angle β on the peak stress, the stress of crack initiation, and the stress of crack coalescence are also investigated in detail.

Lattice Numerical Simulations of Lab-Scale Hydraulic Fracture and Natural Interface Interaction

Hydraulic fracturing is the prime technology for enhancing production from unconventional reservoirs. Design and operation of hydraulic fracturing requires adequate knowledge of formation properties, in situ stresses and fluid properties, due to its complex nature. One of the challenges, that have been the subject of many past studies, is the interaction mechanism when hydraulic fracture intersects a natural interface (e.g., natural fracture or interbed). Crossing, arresting and opening are the known interaction mechanisms. The formation properties, state of in situ stresses, stress contrast, strength properties of the interface, angle of intersection and injecting fluid characteristics affect the interaction mechanism to different extents. The use of numerical models is widespread in simulation of hydraulic fracturing. The use of methods based on the continuum (e.g., FEM) and discontinum (e.g., DEM) representation of media is subjected to some limitations in predicting the correct geometry of the propagating fracture. Lattice method, which is based on the bonded particle approach, has shown promise in simulating hydraulic fracturing. In this paper, lattice modeling is used to simulate the interaction mechanism of lab experiments carried out on mortar samples but at larger scales. The cubical mortar samples of 10 cm size had two synthetically built natural fractures with different angles of approach and filled with different types of glue. The effect of intersection angle and the mechanical properties of the interface were simulated numerically under conditions of viscosity-dominated fracture propagation regime as occurred in the lab. The results demonstrate the advantages of lattice simulation to study the impact of each parameter on the fracture interaction. A larger angle of approach and stronger glues are shown to promote the crossing mode. The shear strength and stress anisotropy are the main parameters influencing the interaction mechanism.

Modeling Effect of Intersection Angle on Near-Bed Flows for Waves and Currents

The flow behavior of turbulent wave boundary layers with weak currents was described using a numerical model. Horizontal velocities, shear stresses, turbulent eddy viscosities, and apparent roughnesses were described. The numerical model is based upon the fluid continuity and momentum equations in the vertical plane. The momentum equations retain the advection terms with vertical orbital velocity in contrast to previous numerical models. The horizontal velocities were calculated from the momentum equations, and the vertical orbital velocity distribution was obtained from the continuity equation. The Reynolds terms were modeled by a mixing length hypothesis. The model was compared with existing models for the wave friction factor by switching off the advection terms and produced similar answers to two existing models. Next, the model was applied to a wave-only flow case iwth the advection terms retained. The model reproduced the measured mass transport profile by van Doorn and Godefroy reasonably well. The model was then applied to wave-current flow cases with arbitrary intersection angles. The model results for 0°, 180°, and 90° agreed well with measurements by van Doorn and Godefroy and van der Stel and Visser, respectively. The model produced significant differences between the following and opposing current cases for the same wave condition. The model results suggest that the wave boundary layer flows for relatively strong waves and weak currents can be accurately described by taking account of the nonlinear advection terms by means of the vertical wave orbital velocity.

Effect of intersection angle between saturation and probe beams on saturated absorption spectra of the Cs- D2 line

The effect of intersection angle between the saturation and probe beams in saturation spectroscopy of the Cs- D 2 line is analyzed. The spectral width of the resonance line increases almost linearly with the intersection angle, while the width of the cross-over line remains almost constant. The peak value of the resonance line decreases non-linearly with angle, while the peak value of the cross-over line is also almost constant.

Effect of intersection angle between saturation and probe beams on saturated absorption spectra

The effect of intersection angle between saturation and probe beams in saturation spectroscopy is analyzed. The spectral width of the resonance line almost linearly with the intersection angle, while the width of the cross-over line remains almost constant. The peak value of the resonance line decreases non-linearly with angle, while the peak value of the cross-over line is also almost constant.