Risks and Sustainability in Construction

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Publications

Design and characterisation of customised-roughness beds for open-channel flow experiments

Publication . Isidoro, Jorge; Martins, Ricardo; Pereira, Luísa Gomes; de Lima, João L.M.P.

The use of laboratory channels or flumes for open-channel flow research is widespread. However, this type of equipment is often expensive, susceptible to damage, and require regular maintenance. In open-channel flow, the roughness of the channel bed is a critical property in governing the flow characteristics. Unfortunately, changing the bed properties, particularly its roughness, proves to be a challenging and time-consuming task in most laboratory channels. To address these limitations, this stud introduces a novel and cost-effective technique to build laboratory channel beds with tailored roughness. Additionally, we describe a precise photogrammetric based method for quantifying the absolute roughness of the bed. These engineered beds can be seamlessly in tegrated into various laboratory channels without posing any risk of equipment damage. In addition, they offer the flexibility to be modified to meet specific roughness conditions, thus advancing the capabilities of experi mental setups in hydraulic studies Furthermore, these specially designed beds can find utility in other facilities where control of surface properties is necessary.

2023Journal article

Restricted access

Estimating sheet flow velocities using quinine as a fluorescent tracer: bare, mulched, vegetated and paved surfaces

Publication . Zehsaz, Soheil; de Lima, João L. M. P.; de Lima, M. Isabel P.; MGP Isidoro, Jorge; Martins, Ricardo

When direct flow velocity measurements are not feasible, the use of tracers can be a valuable tool. In the present study, both laboratory and field experiments were conducted to evaluate the applicability of quinine as a fluorescent tracer for estimating mean sheet flow velocities in different ambient light and surface morphology conditions. Quinine excels in low-light conditions when exposed to UVA light. This tracer was compared with dye and thermal tracers, all in liquid form. In these tracing techniques the tracers were injected into the flow, after which surface velocity was estimated by tracking the leading edge of the tracer plumes and applying a correction factor to calculate the mean velocity (in a water column). The visibility of the tracers was evaluated by measuring the relative luminance and contrast ratio of the quinine and dye tracer plumes. Results show that the quinine tracer can be used to estimate sheet flow velocities over a wide variety of soil and urban surfaces; it has better visibility in comparison to the dye tracer but, in some conditions, lower visibility than the thermal tracer. Although quinine is invisible under bright ambient light conditions, this tracer technique requires low-cost experimental setup and is useful in low-light conditions (e.g., night; twilight; shielded environments).

2022-10-29Journal article

Open access

Fluorescent quinine-based tracking techniques for measurement of open-channel surface flow velocities under low luminosity conditions using a UAS

Publication . Zehsaz, Soheil; L. M. P. de Lima, João; Isidoro, Jorge; de Lima, M. Isabel P.; Martins, Ricardo

This study presents techniques based on the use of fluorescent quinine as a visual tracer for surface flows, to assess surface flow velocities in channels and streams under low luminosity conditions. Fieldwork was conducted in three open channels, with different hydraulic characteristics. A quinine solution, in both liquid and solid (ice cube) forms, was applied on the water flow surface and an Unmanned Aerial System (UAS) was used to record the movement of the fluorescent quinine. The results were compared to the velocities estimated using the thermal tracer technique and flowmeter-based velocity maps. The findings show that the quinine solution, in both liquid and solid forms, can be used to estimate open-channel surface flow velocities under low luminosity conditions. While the solid form of the quinine tracer was applied in a smaller volume than the liquid tracer, its fluorescence effect persisted longer. By comparison, the liquid tracer had the advantage of continual availability and was devoid of the constraint of melting.

2023Journal article

Open access