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. DFT, 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 the 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, LNN

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,  qFLOW (a Helmholtz research initiative project,2026-2029), ENAMIC (a DFG project, 2026-2029), HZDR-Joint-Doctorate (2026-2029).

Collaboration Partners:

IFUNSURF, TU Dresden (TUD), Leibniz Institut für Polymerforschung Dresden (IPF), North Carolina State University (NC State), Peking University, PolyU, KIT, Seoul National University (SNU), IIT Bombay, Sabanci University (SU), Inha University (IU), CUMT, etc.  

Selected Publications

• Zhou, M.; Lin, Y.; Geng, Z.; Zhang, F.; Zhou, L.; Shen, Y.; Zhang, L.; Ding, W.; Bonaccurso, E.;; Chen, L.; Wallmersperger, T.; Zhao, B.; Auernhammer, G. (2026);
  Dual pathways of air cavity evolution during droplet impact on superhydrophobic nanoporous surfaces;
  Physical Review Letters 136(11) 114001;
• Dai, H.; Ding, W.; Schwarzenberger, K.; Vadlamudi, S.R.G.; Yang, X.; Eckert, K. (2026);
  Inerfacial mass transfer enhancement induced by bubble bouncing and shape oscillations;
  Journal of Colloid and Interface Science, 140205;
• Zhao, P.; Vadlamudi, SRG.; Zhou, M.; Zhao, B.; Huang, J.; Auerhammer, GK.; Hampel, U.; Ding, W. (2026);
  Large contact angle hysteresis enhances post-impact droplet oscillations;
  Droplet e70047;
• Yu, F.; Luo, X.; Hampel, U.; Wang, Q.; Ding, W. (2026);
  Experimental study of flow boiling performance in novel space-filling fractal-tree minichannel rectangular heat sinks;
  Applied Thermal Engineering, 288 (1) 129577
• Manthey, J.; Ding, W.; Mehdipour, H.; Guesmi, M.; Unz, S.; Hampel, U.; Beckmann, M. (2025);
  Growth of a Single Bubble Due to Super-Saturation: Comparison of Correlation-Based Modelling with CFD Simulation;
  ChemEngineering 9(3), 63; https://doi.org/10.3390/chemengineering9030063
• 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. (2025);
  Electrolyte spraying within H2 bubbles during water electrolysis;
  Nature Communication16, 4580 https://doi.org/10.1038/s41467-025-59762-7.
• 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
• 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