Assistant Professor Wind Energy Dries Allaerts passed away

News - 14 October 2024

We are very sad to have to inform you that our colleague Dries Allaerts passed away on 10th October. Dries was Assistant Professor Wind Energy.

Dries Allaerts made a significant impact in the field of wind plant aerodynamics. He was the first researcher to look in detail at the phenomenon of (especially offshore) wind farms triggering atmospheric gravity waves that could affect their efficiency. During his PhD and later as a post-doctoral researcher, he developed and applied both high fidelity and reduced order models to quantify the two-way interaction between wind farms and the atmosphere and the impact on wind farm performance. He was recruited to the faculty’s Wind Energy section to research the impact of large offshore wind farm clusters in the North Sea.

Dries Allaerts studied Mechanical Engineering at KU Leuven (Belgium), receiving his MSc degree in 2012. In 2016, he completed his PhD degree in Mechanical Engineering at KU Leuven in the group of Prof. Johan Meyers on the topic of ‘Large-eddy simulation of wind farms in conventionally neutral and stable atmospheric boundary layers’. He was then appointed as a post-doctoral researcher in two institutions: first at KU Leuven, then at the National Renewable Energy Laboratory (USA) in the group of Dr. Matt Churchfield. During his time at NREL, he worked on mesoscale to microscale coupling of models for wind energy resource assessment. After his stay in the USA, he relocated to Europe and was a R&D engineer at the company Diabatix (Belgium) for 6 months before joining TU Delft as an Assistant Professor in May 2020.

In June 2023, Dries was diagnosed with cancer and despite treatment he passed away on 10th October 2024, surrounded by his family.

Dries touched and inspired us, and we shall miss him deeply, but we will continue to carry a little of his spirit within us. We send our heartfelt condolences to his wife Fran and their children Emil, Nore and Suzie, wishing them the strength to get through this very difficult period.

We have set up a memorial corner with a condolence book in the entrance hall of the faculty for those who wish to express their condolences to Dries' loved ones.

You can also leave a condolence message or make a donation to the ‘Kom op tegen Kanker Fund’ in commemoration of Dries through this link.

Henri Werij, Dean

Axelle Viré, Department Chair Flow Physics and Technology Simon Watson, Chair Holder Wind Energy Systems

In Memoriam Dries Allaerts

Scarcely three years after completing his PhD under the supervision of Prof Johan Meyers at KU Leuven, Dries had already created quite a stir with his work investigating how large offshore wind farms could induce atmospheric gravity waves and the impact they might have on the performance of wind farms such as those in the Belgian-Dutch cluster. It was already known that this could occur, but Dries was the first researcher to really draw attention to the fact that the two-way interaction between wind farms and the atmosphere should be properly modelled to really understand their performance. His passion for mathematics led him to develop a reduced-order model of wind farm output that allowed a rapid assessment of different wind farm layouts. This model has been further developed by others such as Sebastiano Stipa, then doing his PhD at UBC in Canada, who spent a highly productive research visit working with Dries at Delft in 2022.

Back in 2019, his reputation had preceded him. When we were looking for a new assistant professor to work in the Wind Energy Systems group and I saw his name on the applicant list, I knew we had a very able candidate and in 2020 he was appointed to the Wind Energy Section. Prior to starting at Delft, Dries had made quite an impression at the National Renewable Energy Laboratory in the US within the group of Dr Matt Churchfield. It was there that he worked on the coupling of mesoscale and microscale models which was then and is still now a very hot topic. During his time at NREL, he made many friends, and his network held him in good stead for his research at TU Delft. Boulder and the Rocky Mountains allowed Dries and his wife Fran to indulge their passion for trekking. Nonetheless, an urge to return to Europe led to a brief period working in the private sector back in Belgium before we snapped up this young talent. Once settled in the Section, Dries set about making his mark reaching out to colleagues in the AE faculty and beyond to further his research on wind plant aerodynamics. This included working with Prof Stefan Hickel in the Aerodynamics Section on LES models and with Prof Jan-Willem van Wingerden on data-driven control of wind turbines and wind farms. He was instrumental in resurrecting the bi-weekly seminars in the Wind Energy Section so that the young researchers could present their latest work and get feedback from their colleagues.

His appointment came during the Covid period, and our first interactions were via Teams. Nevertheless, I would always look forward to our meetings. Dries was always full of new ideas and enthusiasm. We shared a similar sense of humour which always helped of course. When the Covid period ended, face-to-face meetings became possible again. This led to meetings around the coffee table downstairs in the cafeteria. Many is the time that Dries would nag me to use the stairs rather than the lift – probably testament to his love of hiking. Occasionally, meetings would take place after work at some local pub in Delft. Needless to say, this Belgian had little time for the likes of Jupiler or Heineken. Only the best Belgian beers would do and quite right too!  Experiencing this kind and warm-hearted Belgian during rare moments outside work was truly enjoyable.

Dries had a keen eye for detail and a passion for mathematics. I made use of this when I wanted someone to proofread my book. He cared very much about his PhD candidates and encouraged them to think carefully about their research including what they were doing and why. His willingness to make a difference and promote open science led him to publish his codes whenever possible using GitHub, e.g. the Linear Buoyancy Wave Package (LBoW) for solving uniform stratified flow over terrain features.

Although, Dries was very passionate about his work, he understood what was important in life and made plenty of time for his young family. He also had a passion for music playing clarinet in an orchestra which was where he was to meet his future wife, Fran. Family life meant he had less time for this in later years.

In the summer of 2023, he was diagnosed with cancer and had to go on long-term sick leave. But this did not dampen his passion for atmospheric modelling of wind farms. He continued to spend his time reading and meeting his PhD candidates online (and occasionally in person) when he was able to between bouts of treatment. We will remember Dries for the great passion for his work and he would think nothing about commuting 180km to be part of the right research group (he continued to live near his family in Belgium). He had a commitment to doing fundamental science but science that would make a practical difference and this was something that was especially inspiring.

He had an amazing drive to make a difference, and had incredible strength. It was impressive to witness that these qualities never left him during his sickness. As a true Belgian, he also had a unique sense of humour. We will never forget how he was able to make us all laugh, even in the toughest moments.

His presence at the Torque 2024 wind energy conference was something which brought him much energy despite the toll that his illness was clearly having. It was joy to see him so happy and energised during that period. Sadly, this period of re-energisation was to be short-lived.

A bright star has been extinguished far too young, but his spirit will live on. We will miss him deeply.

Simon Watson, with contributions from others in the Wind Energy Section and Department of Flow Physics and Technology