OK, one last time we will revisit the CEDA Dredging Days. There was so much to see and experience, that there could be some more posts about them. However, daily life already demands more of my focus and there are fun facts to tell about them also. The conclusion of this series is about a well-deserved IADC award to Jordy Boone. Both, because he did write a terrific article and we will read more about it in the Terra et Aqua journal soon enough.
So, why was his article and presentation so special? Hopper loading is one of the key process components in the production cycle of a trailing suction hopper dredge. And therefore there is a lot of interest in this subject. Countless articles and numerous experiments have been performed on this topic, resulting in a lot of different hopper models. Traditionally a literature review starts with Camp (1936). And there are a lot of models that build on that approach. Camp and the derived models are similar to the Lagrangian approach, where they follow the trajectory of a single particle.
A whole different approach is to follow Euler and fix the frame of reference. The contents of the system has to be modelled as a continuum. Ground breaking work has been done by van Rhee. He modelled the hopper in a 2D environment and based a more comprehensive 1DV model on that. Others have followed up and so does Jordy Boone.
Other approaches don’t take any physics in their modelling, but consider the hopper as a process block in a control system. At the moment they are only useful for monitoring and controlling an existing system, they don’t have a predictive value, yet.
In this overview, we can see, that the 1DH Boone model is part of the Euler family. Normally solving multi-dimensional 2D and 3D Euler problems tend to be slow. Van Rhee already pointed this out and part of his PhD. thesis was the presentation of a more comprehensive 1DV model. Basically a column cross-section through the hopper. Mixture would be deposited on the bed and water flows up and out of the system. Where that model does lack the influence of the density current, Boone literally upended this simplification by using horizontal strata in the hopper. Here, the mixture section can incorporate the horizontal density current conditions. This will give correct mass and momentum equations. Vertical exchange processes are than calculated by closure relations.
On top of the cake, Boone also verified his approach in laboratory experiments and prototype measurements. As his manuscript is also well written and accessible, he rightfully received the IADC Young Authors Award. Keep up the good work Jordy, we hope to see more interesting work from you.
J. Boone, J, de Nijs, M.A.J., (2017) “1DH Modeling of Transport and Sedimentation Inside a Hopper of a Trailing Suction Dredger” CEDA Dredging Days 2017
Note: Not available online yet. Depending on publication by CEDA.
Overview of hopper loading models by Ben Sloof
Nice report with an overview of the various hopper loading models