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PhD "Understanding the melting dynamics in turbulent flows", Physics of Fluids Group, University of Twente (Netherlands)

Du 1 juillet 2022 au 30 septembre 2026

Starting date : as soon as possible
Duration : 4 years
Site actualite

Contact :
Sander Huisman 
s.g.huisman@utwente.nl

Melting, dissolving, and erosion are processes that are frequently found in nature and technology. Contrary to common believe these three processes do not always smooth the surface, but rather form structures and sometimes even sharpen the surface. This leeds to the formation of e.g. ice scallops and pinnacles, for some examples of patterning and roughening. The continuously changing shape of e.g. a melting iceberg and its interaction with the external turbulence is very complicated as it involves three boundary layers: kinetic, thermal, and solutal (due to the salt concentration). The interaction between those boundary layers is highly complex and not understood. In particular, what is the effect of the surface roughness on the melting rate? The aim is to study the interaction of these boundary layers in a controlled lab environment such as to increase our understanding of these phenomena and their relevance on e.g. the melting rate of ice of icebergs and (tidal) glaciers, all important in view of global war

Understanding the melting dynamics in turbulent flows

 

 

Project name : MeltDyn
Funding Agency : European Research Council (ERC)
Type : 3 PhD positions
Start : 2022–2023
Duration : 4 years

Location : University of Twente, Enschede, Netherlands
Faculty : Science & Technology
Group : Physics of Fluids (Chair: Professor Detlef Lohse)
Supervisor :Assist. Prof. Dr. Sander Huisman

Melting, dissolving, and erosion are processes that are frequently found in nature and technology. Contrary to common believe these three processes do not always smooth the surface, but rather form structures and sometimes even sharpen the surface. This leeds to the formation of e.g. ice scallops and pinnacles, see fig. 1 for some examples of patterning and roughening. The continuously changing shape of e.g. a melting iceberg and its interaction with the external turbulence is very complicated as it involves three boundary layers: kinetic, thermal, and solutal (due to the salt concentration). The interaction between those boundary layers is highly complex and not understood. In particular, what is the effect of the surface roughness on the melting rate? The aim is to study the interaction of these boundary layers in a controlled lab environment such as to increase our understanding of these phenomena and their relevance on e.g. the melting rate of ice of icebergs and (tidal) glaciers, all important in view of global warming and precision required in technological applications.

 

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FIG. 1. Patterns in melting, dissolving, and ablation: a: Submerged side of a freely-floating iceberg (size of a scallop (dimple) ≈ 10 cm) [1]. b: Overturned iceberg revealing scalloped surface [2]. c: Blue ice of Antarctica (penguins for scale) [3]. d: Ice tunnel with ≈ 1 m features [4]. e: Beverage cooled by melting ice cubes. f: Meteorite shows regmaglypts [5]. g: Dissolution by free convection of a salt block in water, striped instability visible (≈ 50 cm view) [6]. h: Surface morphology of salt surface exposed to water (≈ 1 cm features) [7]. i: Caramel block dissolving into water (5 mm features) [8].

This projects cover a wide variety of topics to be explored experimentally: 3D characterization of the scalloping surface, entrainment of the melting (or dissolving) substance in the recirculation zone of the scallops, heat flux measurements, study advancing/receding freezing/melting surfaces in a controlled manner, find the effective friction coefficient of a scalloped surface, melting/dissolving of freely-moving particles in turbulence, varying the saly-concentration since the object can either disappear through melting (heat transfer controlled) or through dissolution (salt transfer controlled), the transition between those regime has not been explored. We will use the latest PIV, PTV, LDA, thermistor, CTA, PLIF, torque measurements, and scanning laser sheet profilometry techniques using low and high speed cameras in combination with high-power pulsed lasers. These experiments will be performed in 5 world-leading flow facilities, see fig. 2.

 

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FIG. 2. All setups that will be used for this research. a: Homogeneous isotropic turbulence facility with 20 engines. b, c: Twente Water Tunnels [9, 10] with large test sections and active grids to enhance and control the turbulence. d, e: Turbulent Taylor–Couette facilities [11, 12], the flow between concentric, coaxial rotating cylinders. Ice (alternatively sugar) particle/surfaces are drawn in Fig. a–d, Fig. e has a replica surface. Each facility is brine proof and has a scale bar of 1 m.

Your profile:

– You have a strong background in (applied) physics, aerospace engineering, or mechanical engineering, or in a closely related discipline. You have strong communication skills, including fluency in written and spoken English. You are enthusiastic and highly motivated to do a PhD. Experimental experience, extended knowledge on fluid mechanics, and experience in image and data analysis are required.

Our offer:

  • –  We want you to play a key role in an ambitious project in an inspiring and stimulating international work environment.

  • –  We provide excellent mentorship and a stimulating, modern research environment with world-class research facilities.

  • –  You will have an employment contract for the duration of 4 years and can participate in all employee benefits the university offers.

  • –  You will be embedded in a dynamic research group with colleagues working on similar topics.

  • –  Additionally, the University of Twente is a green campus with excellent facilities and resources for

    professional and personal development, and offers a wide variety of sports facilities.

  • –  You will follow a high-quality personalized educational program.

  • –  The research will result in a PhD thesis at the end of the employment period.

  • –  We strive for diversity and fairness in hiring.

    Applicants should be in the possession of a master degree in physics, aerospace engineering, mechanical engineering, or closely related field. Applications should provide:

    1. A motivational letter (1 page max) describing why you want to apply for this precise position.

    2. Description of your research interests/experience and how do they connect to this position.

    3. A detailed CV.

    4. Academic transcripts from your Bachelor’s and Master’s degrees.

    5. To assess a variety of skills we ask you to perform analysis on a data set and write a tiny report.

    6. Name and email addresses of at least two visible references who are willing to send a letter of recommendation on your behalf.

    7. An interview with a scientific presentation on your previous work will be part of the interview process.

    Potential applicants are encouraged to apply to Assist. Prof. Sander Huisman. See details here https://pof.tnw.utwente.nl/vacancies/37.

References

  1. [1]  B. W. Hobson, A. D. Sherman, and P. R. McGill, Imaging and sampling beneath free-drifting icebergs with a remotely operated vehicle, Deep Sea Research Part II: Topical Studies in Oceanography 58, 1311 (2011).

  2. [2]  S. Weady, Self-sculpting of melting ice by natural convection, (2020).

  3. [3]  E. Rock, Blue ice, Daily Wild Life Photo (2014).

  4. [4]  P. Claudin, O. Dura ́n, and B. Andreotti, Dissolution instability and roughening transition, J. Fluid Mech. 832 (2017).

  5. [5]  G. Kurat, Personal photo (2016).

  6. [6]  C. Cohen, M. Berhanu, J. Derr, and S. C. du Pont, Buoyancy-driven dissolution of inclined blocks: Erosion rate and pattern formation, Phys. Rev. Fluids 5, 053802 (2020).

  7. [7]  T. S. Sullivan, Y. Liu, and R. E. Ecke, Turbulent solutal convection and surface patterning in solid dissolution, Phys. Rev. E 54, 486 (1996).

  8. [8]  C. Cohen, M. Berhanu, J. Derr, and S. C. du Pont, Erosion patterns on dissolving and melting bodies, Phys. Rev. Fluids 1, 050508 (2016).

  9. [9]  R. E. G. Poorte and A. Biesheuvel, Experiments on the motion of gas bubbles in turbulence generated by an active grid, J. Fluid Mech. 461, 127 (2002).

  10. [10]  B. Gvozdi ́c, O.-Y. Dung, D. P. M. van Gils, G.-W. H. Bruggert, E. Alm ́eras, C. Sun, D. Lohse, and S. G. Huisman, Twente mass and heat transfer water tunnel: Temperature controlled turbulent multiphase channel flow with heat and mass transfer, Rev. Sci. Instrum. 90, 075117 (2019).

  11. [11]  D. P. M. van Gils, G.-W. Bruggert, D. P. Lathrop, C. Sun, and D. Lohse, The Twente turbulent Taylor–Couette (T3C) facility: Strongly turbulent (multiphase) flow between two independently rotating cylinders, Rev. Sci. Instrum. 82, 025105 (2011).

  12. [12]  S. G. Huisman, R. C. A. van der Veen, G.-W. H. Bruggert, D. Lohse, and C. Sun, The boiling Twente Taylor–Couette (BTTC) facility: Temperature controlled turbulent flow between independently rotating, coaxial cylinders, Rev. Sci. Instrum. 86, 065108 (2015).