Pedro Lopes

Numerical and experimental investigation of a gully under surcharge conditions

This paper deals with numerical and experimental investigation of a gully under exceptional situations after the sewer system becomes pressurized. These results are useful for the calibration and validation of the linking elements found in Dual Drainage (DD) models. The experimental results were obtained in the MLE (Multiple-Linking-Element) experimental installation that allows the simulation of full surcharge flow through a gully. The installation consists of an 8 m long and 0.5 m wide channel, fitted with a 0.6 × 0.3 × 0.3 m gully with a 80 mm diameter pipe inlet at the bottom. The numerical results were obtained using a three-dimensional structured mesh simulated in the OpenFOAMTM Toolbox. The results characterization focuses mainly on the jet area, whereby pressure-flow relations were derived for this specific gully. The good agreement found between numerical and experimental results, allowed the extrapolation to larger flow rates.

Assessment of the Ability of a Volume of Fluid Model to Reproduce the Efficiency of a Continuous Transverse Gully with Grate

This paper deals with the numerical investigation of the drainage efficiency of a continuous transverse gully with the grate’s slots aligned in the flow direction and compared with experimental data sets. The gully efficiency attained with a three-dimensional (3D) numerical model is compared and validated against experimental data. The numerical simulations are performed using a computational fluid dynamics volume of fluid solver. Different slopes, from 0 to 10%, and a wide range of drainage flows, from 6.67 to 66.67??L/s/m66.67??L/s/m, are simulated. The linear relation between Froude number and efficiency of the gully is in agreement to the one experimentally obtained.

Autonomous Selection of Closing Posture of a Robotic Hand Through Embodied Soft Matter Capacitive Sensors

Soft matter capacitive sensors are developed and integrated into the silicone skin of finger tips and palm of a robotic hand. Distributed sensing nodes are used for obtaining preliminary pre-touch information about the object that should be grasped. This includes conductive objects taking advantage of proximity sensing from changes in electric field and non-conductive objects taking advantage of pressure sensing from the deforming capacitive electrodes. We argue that this system can eventually address one important challenge in control of multi-DOF bionic hands, i.e., autonomously choosing the right closing pattern. Sensor fabrication, characterization, and integration into the hand are described. An algorithm for detection and activation of closing patterns is suggested, and results are discussed.

Numerical Investigation of the Flow Field inside a Manhole-Pipe Drainage System

Urban drainage networks contain a large number of structures. The manhole is the most common and the most important as it connects pieces of sewer pipes to form sewer networks. Understanding the hydraulics of a manholepipe drainage system is important as this may sometimes become the bottlenecks of the sewer systems. In this study, the flow structure and flow hydraulics of a specific manhole-pipe sewer system was analysed numerically in view of further research to investigate sediment and suspended solid transport in the system. The numerical model was compared with discharge and water pressure/depth data from an experimental model. Different discharges and water levels at the inlet pipe were applied, and corresponding change of flow hydraulics were analysed. Two scenarios were tested: (1) free surface flow and (2) pressurized flow condition in the pipe. In the numerical analysis, the k-e turbulent model was used within open source CFD tool OpenFOAM®. The numerical results showed similar flows and water pressure levels to that of the experimental work. Different flow patterns were observed in the manhole at different discharges. This flow pattern will give further insight in assessing pollutant flow inside the system.

Investigation of the Flow Field inside a Drainage System: Gully - Pipe - Manhole

Gully drop connected with manhole is one crucial structural part in several urban drainage systems. This paper analyses the flow pattern and flow hydraulics of a gully-manhole drainage structure. Analysis is done numerically using computational fluid dynamics CFD tools OpenFOAM®. Data from the Dual Drainage / Multi Link Element installation (DD-MLE) at the University of Coimbra hydraulic lab is used to validate the numerical simulations. The experimental model setup consists of a 0.5 m wide channel, a 0.6 × 0.24 × 0.32 m (L × W × D) gully, a gully outlet with an 80 mm diameter pipe and a manhole of 1 m diameter with a 300 mm inlet and outlet pipe connected. The flow pattern is observed under drainage flow conditions with different surcharge heights of the manhole. It has been observed that the intercepted flow through the gully decreases with the increase of surcharge in the manhole. The shear stress at the gully floor is found much higher than that of manhole floor. This indicates the probability that bigger sediment particle can be transported through gully but will remain deposited at the manhole floor. The flow pattern in the manhole changes with the change of surcharge height. The flow through the manhole inlet seems to disperse less at higher surcharge.

Numerical and experimental study of the fundamental flow characteristics of a 3D gully box under drainage

Numerical studies regarding the influence of entrapped air on the hydraulic performance of gullies are nonexistent. This is due to the lack of a model that simulates the air-entrainment phenomena and consequently the entrapped air. In this work, we used experimental data to validate an air-entrainment model that uses a Volume-of-Fluid based method to detect the interface and the Shear-stress transport k-ω turbulence model. The air is detected in a sub-grid scale, generated by a source term and transported using a slip velocity formulation. Results are shown in terms of free-surface elevation, velocity profiles, turbulent kinetic energy and discharge coefficients. The air-entrainment model allied to the turbulence model showed a good accuracy in the prediction of the zones of the gully where the air is more concentrated.

Self-Aeration Modelling Using a Sub-Grid Volume-Of-Fluid Model

Abstract The accurate prediction of self-aerated flow is not always easy to obtain, particularly if the computational performance is the main concern. Two-fluid formulation is suitable to simulate the dispersed air in a continuous water phase (e.g. bubbly flows) in a fine mesh, whereas the interface tracking methods are used for sharp interfaces with two continuous and contiguous phases (e.g. free-surface flows). Several approaches have emerged to combine both methods; however all found a gap in the transition between resolved and unresolved scales of air at the interface. Including a source term that predicts the self-aeration process is viewed as a promising step to overcome such difficulty. In this work, we added to the volume-of-fluid formulation an extra advection-diffusion equation connected to a source of air at the free surface to simulate the dispersed bubble phase. One-way coupling and two-way coupling versions of this model are tested along with sensitivity tests to show the accuracy of the new source term that does not require calibration. The location of the aeration is analysed and investigated. Results are obtained in terms of free-surface flow depths, air–concentration profiles and velocity fields and compared to experimental data acquired in a scaled stepped spillway model with good agreement. The free-surface given by the air-entrainment model is in good agreement in both non-aerated and aerated zone of the spillway.

SCALA—A Scalable Rail-based Multirobot System for Large Space Automation: Design and Development

In this paper, a prototype of the SCAlable ModuLar (SCALA) multiagent robotic system is developed and implemented. This system for automation in large spaces relies on mobile agents that move on a planar and modular mesh of rails with embedded accurate positioning sensors. Groups of three mobile agents are joined together to drive a parallel manipulator, thus allowing fine manipulation tasks to be performed on a large workspace. The mechanical, mechatronics, and control solutions adopted on the prototype are reported and discussed, as well as its performance on the several tests performed.