Nano- and Micro scale modelling

Motivation

We focus on nano/micro-scale modeling of fluid dynamics and mass transport in phase change processes involving solid walls. Our primary strategy is to apply nano/micro-scale simulations and experiments (E.g. Molecular Simulation, Kinetic Monte Carlo, Direct Numerical Simulation, Laser Interferometry Method, Sychrontron X-ray Radiography) to achieve a fundamental understanding of wetting phenomena, taking into account the local instantaneous bubble/droplet oscillation dynamics. We further apply this understanding to explore innovative surface designs for various applications, such as boiling, cavitation, and spray cooling, aiming to enhance both safety and efficiency.

Bubble Related,  Cavitation Related, Droplet Related, Exemplary Applications, Team Members, Projects, Selected Publication.

Bubble Related 

j.zhang@hzdr.de; s.vadlamudi@hzdr.de;

Goals:

The primary objective of this research is to unravel the physics governing microlayer morphology and its impact on heat transfer in nucleate boiling. Specifically, this study aims to:

1. Develop a fundamental understanding of microlayer formation and evaporation across smooth and structured surfaces and provide an accurate description of the microlayer morphology.

2. Establish a comprehensive relationship between the surface characteristics, microlayer morphology, and microlayer heat transfer performance in nucleate boiling based on a thorough understanding of the interactions between surface and microlayer.

3. Develop a strategy for surface engineering to enhance the heat transfer performance of the microlayer and nucleate boiling guided by the established relationship.

Highlights

- A multiscale approach integrating Molecular Dynamics (MD) simulations, Direct Numerical Simulations (DNS), and experimental investigations.

- Development of a three-region microlayer morphology description that bridges nanoscale wetting dynamics with mesoscale microlayer structures.

- Identification of distinct microlayer morphologies (undisturbed, disturbed, and disrupted) on micro-pillar arrayed surfaces and their influence on heat transfer.

- Experimental validation of microlayer morphology using high-speed imaging and synchrotron X-ray techniques.

- Establishment of design principles for optimizing nucleate boiling heat transfer through surface engineering.

 

Cavitation Related

m.abdelsalam@hzdr.de

Goals

The cavitation - vortex - turbulence (CVT) interaction, which determines the cavitation intensity, location and shape is not yet understood quantitatively. Accordingly, the promotional effect of CVT on diffusion and reaction of OH radicals cannot be assessed. In this project, the effect of the CVT interactions will be characterized in terms of vortex stretching and dilation. These micro-scale models based on direct numerical simulations (DNS) will quantitatively predict the location and intensity of collapsing cavities, and the reactions of OH radicals.

 

 

 

 

Objectives:

- Characterize the impact of the CVT interaction on cavitation (DNS with the parallel, hierarchic code PHASTA) on a scale of tens of bubbles.

- Quantify the impact of related physical mechanisms on the concentration and diffusion rate of OH radicals with DNS.

- Quantify interactions of diffusion and reactions of OH radicals considering the CVT interaction for different hydraulic conditions.

Droplet Related

P.Zhao@hzdr.de

Goals

Contact angle hysteresis (CAH) plays a critical role in governing droplet dynamics on solid surfaces, with significant implications for industrial applications such as spray cooling, inkjet printing, and coating processes. Droplets impact on low-CAH surfaces and move with minimal resistance on contact line motion, whereas high CAH induces pinning of the contact line. Despite extensive research, the impact of CAH on droplet shape oscillations remains poorly understood. In this study, we investigate droplet dynamics on functionalized surfaces with various CAH, unveiling the underlying mechanisms that govern droplet oscillations and providing insights to optimize surface design for fluidic applications. 

Exemplary Applications:

We further extended our fundamental understanding to applications. Two exemplary applications are introduced here. One is the optimized fractal structure microchannels heat exchanger and twisted heat exchanger pipes. In these two works, we employed the multiobjective optimization method (Genetic Algorithm) and the E/E multiphase simulation code together with our CFD department.

Team Members

Involved Computational Codes and Measurement Facilities

·         High-speed/IR camera, thermal anemometry probes, Boiling facility, Droplet facility, µ-focus X-ray radiation/CT, ROFEX, High-resolution Synchrotron X-ray facility, RC 318 Loop, MORENA for CHF

·         Computational fluid dynamics tools: DNS Code: house developed version of Basilisk, PHASTA, MD code: LAMMPS, Oscillation Mode Decomposition Code

Related Projects:

BMWi-NUBEKS (2014-2019), BMBF-SINEWAVE (2021-2025), EU-MSCA-DN Cavipro (2023-2028), A.v. Humboldt (2024-2026), TUD-Faculty of Engineering-EvoBub (2024-2025), TUD-Faculty of Engineering-EvoDrop (2024-2025), CSC, GEP, DST-DAAD 

Collaboration Partners:

TU Dresden (TUD), Leibnitz Institut für Polymerforschung Dresden (IPF), Nord Calorana State University (NC State), Peking Univeristy, PolyU, KIT, Seoul National University (SNU), IIT Bombay, Sabanci University (SU), Inha University (IU) etc.  

Selected Publications

Zhang, J.; Li R., Vadlamudi S.R.G, Pang C.; Hampel U.; Ding W.; (2025) Heat transfer enhancement for nucleate boiling via microlayer disruption on micro pillar arrayed surfaces, International Journal of Heat and Mass Transfer 241, 126770

Wu, W.; Hampel, U.; Ding, W.*; Sun, B. (2025) A numerical study on heat transfer and boiling crisis in twisted heat exchanger tubes, International Journal of Heat and Mass Transfer 241, 126745

S.R.G. Vadlamudi; Moiz, M; Srivastava, A; Hampel, U.; Ding, W. (2024) On the Quantification of Microlayer Contribution towards Bubble Growth under Subcooled Flow Boiling Regime, Physics of Fluids 36, 9, 091706

Bois, G.; Ding, W.; etc. (2024) Benchmark DEBORA: Assessment of MCFD compared to high-pressure boiling pipe flow measurements. International Journal of Multiphase Flow 179, 104920

Wu, W.; Ding, W.*; Hampel, U.; Sun, B. (2024) Analysis of the influence of swirling flow on the boiling heat transfer characteristics of two-phase flow, International Journal of Heat and Mass Transfer 221, 125075

Dai, G.; Huang, J.; Ding, W.; Qiu, L.; Zhang, W.; Gu Q.; Wang, Z.; Hu, Z.; Duan, C.; Li P. (2024) Orientational mercury removal from aqueous solution using CuxS nanocluster anchored attapulgite. Chemical Engineering Journal 482, 1488831

Bashkatov, A.; Bürkle, F.; Demirkır, Ç.; Ding, W.; Sanjay, V.; Babich, A.; Yang, X.; Mutschke, G.; Czarske, J.; Lohse, D.; Krug, D.; Büttner, L.; Eckert, K. (2024) Electrolyte spraying within H bubbles during water electrolysis. arXiv preprint arXiv:2409.00515, 2nd revision in Nature Communication.

Maestri, R.; Radhakrishnakumar, S.; Bürkle, F.; Ding, W.; Büttner, L.; Czarske, J.; Hampel, U.; Lecrivain, G. (2024) Equilibrium Taylor bubble in a narrow vertical tube with constriction, Physics of Fluids 36, 032108

Yu F.; Ding, W.*; Luo X.*; He B.; Hampel U. (2023) Multi-objective optimization of fractal-tree microchannels in a rectangular heat sink by a distributed-adaptive genetic algorithm, International Journal of Heat and Mass Transfer 217,124672

Zhang, J.; Rafique J.; Ding, W.*; Bolotnov I.; Hampel U. (2023) A direct numerical simulation study to elucidate the enhancement of heat transfer for nucleate boiling on surfaces with micro-pillars, International Communications in Heat and Mass Transfer 147, 106943

Zhang, J.; Rafique J.; Ding, W.*; Bolotnov I.; Hampel U. (2023) Direct numerical simulation of microlayer formation and evaporation underneath a growing bubble driven by the local temperature gradient in nucleate boiling, International Journal of Thermal Sciences 193, 108551

Zhang, J.; Ding, W.*; Hampel U. (2023) How droplet pin on solid surfaces, Journal of Colloid and Interface Science 640, 940-948

Zhang, J.; Ding, W.*; Wang, Z.; Wang H.; Hampel U.; (2023) Microscopic fluid-gas interface effect on liquid wetting, Journal of Colloid and Interface Science, 813-822

Setoodeh, H.; Moonesi Shabestary, A.; Ding, W.*; Lucas D.; Hampel U. (2022) CFD-Modelling of Boiling in a Heated Pipe Including Flow Pattern Transition, Applied Thermal Engineering, 117962

Setoodeh, H.; Ding W.*; Lucas D.; Hampel U. (2021) Modelling and simulation of flow boiling with an Eulerian-Eulerian approach and integrated models for bubble dynamics and temperature-dependent heat partitioning, International Journal of Thermal Sciences 161, 106709

Zhang, X.; Wu, J.; Zhang, H; Ding, W.; Zhang, J. (2021) Visualization of Liquid Reaction in Submerged Top‐blow Agitation Process Fuel Cells 21(1), 18-23

Ding, W.*; Zhang, J.; Sarker D.; Hampel U. (2020) The role of microlayer for bubble sliding in nucleate boiling: a new viewpoint for heat transfer enhancement via surface engineering. International Journal of Heat and Mass Transfer, Vol 149 119239