Measurement of forces on towed objects through cohesive sediment: design, development and data processing
Mahmodi, A. (2014). Measurement of forces on towed objects through cohesive sediment: design, development and data processing. MSc Thesis. KU Leuven. Faculteit Industriële Wetenschappen - Campus Gent: Gent. IV, 112 pp.
Siltation is a huge problem in the estuaries, harbours and water ways. To keep the safe navigable depth one has to apply expensive and time consuming maintenance dredging. One is aware that the current maintenance dredging processes are not efficient. Because of this reason one is looking for new methods to maintain navigable waterways, which cuts drastically in the maintenance costs. An interesting method that could be applied is liquefying the seabed, with a specific critical density. Therefore an excellent understanding is needed in the resistance of dense cohesive sediments against shear stress, caused by an object with a certain speed. This study will provide the necessary parameters concerning the effects exerted by the cohesive sediment on the floating object.
The research is carried out by the Flanders Hydraulic Research in two parallel projects, namely: an experimental research carried out in Flanders Hydraulic Research which is the subject of this thesis and a simulation made by using CFD-software.
In order to start, a measurement set-up is needed to measure the forces exerted on the towed object submerged with a fixed depth in a homogeneous dense cohesive sediment suspension with a specific density. This measurement set-up needs to be calibrated and tested in order to improve the measurement set-up by detecting the start-up problems.
The result of the performed tests has indicated that the data obtained by using the current measurement set-up contains a great noise (the motor and its gear are great sources of noise), which makes it not reliable to take conclusions about the relation between the speed of the submerged towing object, the density of the cohesive sediment suspension and the exerted forces on the towed object. Therefore it is recommended to rebuild the existing set-up and use an alternative driving.
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