Personal – Discover Dredging

Cees van Rhee Passed Away, a Visionary Leader for the Dredging Community

Cees van Rhee at the TU Delft Dredging Technology Laboratory (Credit: TU Delft)

This is an article I didn’t want to write. My professor Cees van Rhee passed away last weekend1. This was devastating news for his family and all those who surrounded him at the TU Delft. Cees was still enjoying life, he died doing his favourite hobby: fishing. Always looking ahead, he was determined to be my promotor for my PhD. project. I know him already so long. When he was doing his PhD. project, I was graduating on my masters in the same lab. It would be fitting to be his last PhD. student. Fate has decided differently. As he was a public figure, you will receive in the news probably some factual biographies about him2. But he was so much a person to me, that I want to highlight some of his thoughts and contemplations for you.

When Cees assumed his position as dredging professor3, he set three goals to work on:

Bring the department of dredging engineering under a single faculty
Improve the quality of research and education
Make the dredging community conscious of designing equipment for performance

He managed to merge the civil engineering branch and the mechanical engineering branch of the dredging engineering department as one of his first feats as new professor. The second goal can be sensed from the enormous increase in publications during his tenure4. And not only in the usual dredging literature, but also in highly regarded scientific journals. A standard he also imposed on my own PhD. project. The final goal is a real dot on the horizon and is therefore harder to achieve. He engaged with the rest of the dredging community through his numerous activities for the CEDA. Bringing his academic perspective to the industry.

In response to the drivers for dredging: population growth, transport demand and sea level rise, he saw the following challenges:

Continuous innovation to stay ahead of the competition
Re-allocation of labour for the manufacturing of equipment
Understanding the dredging processes on a fundamental level
Development of AI for supporting optimal operation

These challenges are still valid and are a sign of his visionary academic approach to dredging. Most of the research are contributing to solve these challenges. As a leader of the department of Dredging Engineering he lead his colleagues into a solid self-supporting team of specialists. I think we are still in a good position to tackle the challenges, but have to be careful to maintain this advantage.

Cees left a legacy of a high academic standard for dredging engineering. Torn away from life and so many projects ongoing, there will be a lot of loose ends to tie. And I am proud, that I can be part of it. When I approached him for my PhD. plans, he suggested to follow certain ideas that have been slumbering around, but were dormant because by now everybody uses finite element applications to study those problems. He was really happy that I came along with my old school analytic competences to pick up that gauntlet. I have some promising preliminary results already. And I am so sorry, he will never be there to enjoy the results that confirm he was onto something good.

We will all miss you. Thank you Cees.

Cees van Rhee welcoming the audience at the 2019 CEDA Dredging Days (Credit: CEDA)

References

Personal Announcement: Going Back To School To Cut Some Clay

Learning early or later in life, studying is always a joy when you make it practical

‘Never too old to learn’ is my motto. Everyday I look around me and I wonder how this beautiful world fits together. Whether it be the stars in the sky, the waves at sea or life as we know it, there is always something to be learned about it. At school, I was not a great pupil, but I was always curious to learn more. For my master thesis at the Delft University of Technology, I investigated the performance of a dredge and made recommendations to improve its operation1. As the project was more focussed on mixture forming (and turbidity) and the redesign of the auger head, there was no attention for the soil mechanics involved in the cutting process.

Fully covered cutter head in sticky clay

Now is the time to get that straight. In my daily business, I came across several projects where the clay cutting was a real problem. This was one of the triggers that sparked my interest in sticky clay and made me pursue a more detailed investigation into this nasty stuff. I am very grateful my management was willing to grant me time to go back to the university and start a PhD project with professor Cees van Rhee to learn more about clay.

Synthesis of clay and the relevant properties for dredging

Clay is a completely different material than sand or rock. Those are either plastic and non-cohesive or elastic and cohesive. Clay is the worst of both worlds: plastic and cohesive. It can be described with certain soil parameters as e.g. undrained shear strength and internal friction angle. The failure model is based on Mohr’s circle etc. But those are all continuum approaches2. When you zoom in to the particle level of clay, a whole new world opens up. I already wrote about the interesting particle interaction in a previous post3.

Boltzmann strain rate function in clay cutting

It appears, that the consistency, deformation and failure of clay is related to the tiny electric charges distributed over the platelet crystals. The movement along the charges needs energy. The model to describe dislocation energies along electric charges has been studied by Ludwig Boltzmann4,5. His model governs a wide range of applications, ranging from cosmology to particle physics. I really plunged into the deep end of science with just simple clay. It already took some time to get my head around the concepts involved. Slowly it dawns on my what possibilities there are to improve our understanding of the cutting of clay and possibly to improve our products eventually.

Gallery of my dredging professors (l) prof. de Koning, (m) prof. Vlasblom, (r) prof. van Rhee

My ‘old professor’ de Koning was a proponent of ‘thinking with your hands’6. Professor Vlasbom encouraged me to graduate on a practical problem and also my current professor van Rhee suggested to do some preliminary experiments with sticky stuff to get some feeling about what I am going to study. Of course I took some clay home to play with it. But the best suggestion was by my colleagues, who thoughtfully gave me stroopwafels7. The ultimate representation of sticky non-Newtonian stuff between layers of latticed disks.

Fresh supply of stroopwafels for practice and celebration

References

2021: Muddling Along To A Healthy Year In Dredging

Calendar picture of a sunny dredging site

Dear readers, I sincerely wish you all the best for this new year. As things are looking positive on the vaccine front, we should keep testing negative this year. There are lots of items and events to look forward. Last year was not quite what we’ve hoped for and wished each other.

I do hope all of you are OK and are still together with your loved ones. I am fortunately in that respect. So, next to the Covid situation, there were a lot of other noteworthy items. Most of them have been featured here on Discover Dredging. My trip to Bangladesh, just before all the lockdown measures. The graduation of Carsten1 and Omar2 that were completely over Teams. Some attention to our Damen Dredging Experience3. And some other items. Did you enjoy the Donald Duck review?4

Opening scene of ‘Muddy Fine Business’ or ‘Success Test’ (Credit: Disney)

One sad event was, the last issue of Dredging and Port Construction5. We’ve had to say goodbye to our trusted DPC. Although by now, there has been a kind of digital revival on the CEDA Website6. They opened up a section for Industry News, edited by Namrata Nadkarni. It stands out from the other online media covering dredging as there has been some attention to smaller topics, that would normally not get covered. As I think it is a good initiative, I urge you to subscribe and also participate by sending them any noteworthy news items for publication. Not specifically the usual company press releases, but also the more thought provocative opinions and perspectives on the activities of our dredging community. Active participation could make this CEDA Industry News flourish this year.

Announcement of the CEDA Industry News section (Credit:CEDA)

Further personal activities within CEDA are the Dredging Management Commission7 and I am looking forward to the exciting new concept for the CEDA Dredging Days8. Will you participate? Also, I already took the course on ‘Dredging for Sustainable Infrastructure’9, but you should keep an eye out on the next instalment, coming soon10.

A continuation from last year on my Discover Dredging will be some more articles on our Damen Dredging Experience. There are still some exhibit left to review and teaser:… There are some new exhibits arriving! Hope to have that covered when the pandemic will fizzle out we can show you around through our museum. And I hope to continue on pump and dredge technology.

Overview of the Damen Dredging Experience

Currently, there are some students working on their graduation thesis. Their very interesting topics will be highlighted here as well. Some others will start soon. When you are looking for a fun place to have your internship our your graduation, you might consider a visit to our career page11 or contacting Frank Bosman for any opportunities. Although most positions are filled at the moment, later this year we would welcome fresh brains again.

As our offices will be closed for regular work, I will be working from home most of the time. Probably most of you will do likewise. To keep track of the passage of time over the days, you should have a calendar. As a special service to my audience, I was granted the use of a set of beautiful pictures to create a calendar. You can download the file here and with some DIY skills you should have some original wall decoration for this year.

Stay healthy and stay safe. Hope to see you later this year.

Category: Personal

Cees van Rhee Passed Away, a Visionary Leader for the Dredging Community

References

See also

Personal Announcement: Going Back To School To Cut Some Clay

References

See also

2021: Muddling Along To A Healthy Year In Dredging

References

See also