Recent publications of the Research Unit

2024

  • Till Zeugin, Fergal B. Coulter, Utku Gülan, André R. Studart, Markus Holzner
    In vitro investigation of the blood flow downstream of a 3D-printed aortic valve
    Scientific Reports, 2024, 14, 1572
    DOI: 10.1038/s41598-024-51676-6

Graphical Abstract
Grapical abstract: Schematic of the setup used to study the blood flow downstream of a 3D-printed aortic valve.

2023

  • F. Pelusi, F. Guglietta, M. Sega, O. Aouane, J. Harting
    A sharp interface approach for wetting dynamics of hydrophobic coated droplets and soft particles
    Physics of Fluids, 2023, 35, 082126
    DOI: 10.1063/5.0160096

Graphical Abstract
Sketch of the wetting dynamics of a generic particle with initial radius R initially placed in contact with a flat wall. The interface is resolved with a 3D triangular mesh.

  • F. Guglietta, F. Pelusi, M. Sega, O. Aouane, J. Harting
    Suspensions of viscoelastic capsules: effect of membrane viscosity on transient dynamics
    The Journal of Fluid Mechanics, 2023, 971, A13
    DOI: 10.1017/jfm.2023.694

Graphical Abstract
Grapical abstract: Immersed boundary–lattice Boltzmann (IB-LB) simulations of viscoelastic spherical capsule suspensions.

  • Yazdan Rashidi, Othmane Aouane, Alexis Darras, Thomas John, Jens Harting, Christian Wagner, Steffen M. Recktenwald
    Cell-free layer development and spatial organization of healthy and rigid red blood cells in a microfluidic bifurcation
    Soft Matter, 2023, 19, 6255-6266
    DOI: 10.1039/D3SM00517H

Graphical Abstract
Grapical abstract: cell free layers develop differently for cells with various rigidities.

  • Steffen M. Recktenwald, Katharina Graessel, Yazdan Rashidi, Jann Niklas Steuer, Thomas John, Stephan Gekle, and Christian Wagner
    Cell-free layer of red blood cells in a constricted microfluidic channel under steady and time-dependent flow conditions
    Phys. Rev. Fluids, 2023, 8, 074202
    DOI: 10.1103/PhysRevFluids.8.074202

Top view (left) and front view (right) of the microfluidic constriction.
Top view (left) and front view (right) of the microfluidic constriction.

  • Mohammed Nouaman, Alexis Darras, Thomas John, Greta Simionato, Minke A. E. Rab,Richard van Wijk, Matthias W. Laschke, Lars Kaestner, Christian Wagner, Steffen M. Recktenwald
    Effect of Cell Age and Membrane Rigidity on Red Blood Cell Shape in Capillary Flow
    Cells , 2023, 12(11), 1529
    DOI: 10.3390/cells12111529

Images of RBC shapes in confined flows.
Images of RBC shapes in confined flows.

  • Marcelle G.M. Lopes, Steffen M. Recktenwald, Greta Simionato, Hermann Eichler, Christian Wagner, Stephan Quint, Lars Kaestner
    Big Data in Transfusion Medicine and Artificial Intelligence Analysis for Red Blood Cell Quality Control
    Transfus Med Hemother , 2023, 50(3), 163-173
    DOI: 10.1159/000530458

Schematic overview of big data in transfusion medicine. The Matryoshka-structured rectangles represent the concept of this review.
Schematic overview of big data in transfusion medicine. The Matryoshka-structured rectangles represent the concept of this review.

  • Laura Hertz, Daniel Flormann, Lutz Birnbaumer, Christian Wagner, Matthias W. Laschke, and Lars Kaestner
    Evidence of in vivo exogen protein uptake by red blood cells: a putative therapeutic concept
    Blood Advances , 2023, 7, 1033–1039
    DOI: 10.1182/bloodadvances.2022008404

Mechanical red blood cell interactions enable intercellular protein transfer.
Mechanical red blood cell interactions enable intercellular protein transfer.

2022

  • O. Aouane, M. Sega, B. Bäuerlein, K. Avila, J. Harting
    Inertial focusing of a dilute suspension in pipe flow
    Physics of Fluids, 2022, 34, 113312
    DOI: 10.1063/5.0111680

 Graphical Abstract
Particle steady-state distribution over the pipe cross section, for Re = 38.

  • Steffen M. Recktenwald, Greta Simionato, Marcelle G.M. Lopes, Fabia Gamboni, Monika Dzieciatkowska, Patrick Meybohm, Kai Zacharowski, Andreas von Knethen, Christian Wagner, Lars Kaestner, Angelo D'Alessandro, and Stephan Quint
    Cross-talk between red blood cells and plasma influences blood flow and omics phenotypes in severe COVID-19
    eLife , 2022, 11, 1–17
    DOI: 10.7554/eLife.81316

Pathological RBC shapes found in COVID-19 patients during microcapillary flow.
Pathological RBC shapes found in COVID-19 patients during microcapillary flow.

  • Daniel Morón, Daniel Feldmann, and Marc Avila
    Effect of waveform on turbulence transition in pulsatile pipe flow
    J. Fluid Mech. , 2022, 948, A20
    DOI: 10.1017/jfm.2022.681

Colour map and isosurfaces of positive (blue) and negative (vermillion) axial vorticity ωz of the optimal helical perturbation of a pulsatile flow driven with a sine wave pulsation at Re=2000, A=1 and Wo=11. In both panels we show a cross-section of the pipe at z=0 to the left; and a section z=1.5D long of the pipe in the right.
Colour map and isosurfaces of positive (blue) and negative (vermillion) axial vorticity ωz of the optimal helical perturbation of a pulsatile flow driven with a sine wave pulsation.

  • Moritz Lehmann, Mathias J. Krause, Giorgio Amati, Marcello Sega, Jens Harting, and Stephan Gekle
    Accuracy and performance of the lattice Boltzmann method with 64-bit, 32-bit, and customized 16-bit number formats
    Phys. Rev. E , 2022, 106, 015308
    DOI: 10.1103/PhysRevE.106.015308

Roofline model analysis of FluidX3D with the D3Q19 velocity set, running on an Nvidia Titan Xp GPU. For each floating-point type, the three data points (left to right) correspond to the SRT, TRT, and MRT collision operators. The arithmetic hardware limit is different for FP64/xx and FP32/xx.
Roofline model analysis of FluidX3D with the D3Q19 velocity set, running on an Nvidia Titan Xp GPU.

  • Felix Maurer, Thomas John, Asya Makhro, Anna Bogdanova, Giampaolo Minetti, Christian Wagner, and Lars Kaestner
    Continuous Percoll Gradient Centrifugation of Erythrocytes—Explanation of Cellular Bands and Compromised Age Separation
    Cells , 2022, 11, 1296
    DOI: 10.3390/cells11081296

(a) Density gradient measurements of Percoll medium by GE Healthcare using colored beads in an angle head rotor at 20,000× g and varying centrifugation duration, (1) 15 min, (2) 30 min, (3) 60 min, (4) 90 min. (b) scheme of the cell-extraction process of from a single band using micro medical tubing and a syringe pump.
Density gradient measurements of Percoll medium.

  • Steffen M. Recktenwald, Marcelle G. M. Lopes, Stephana Peter, Sebastian Hof, Greta Simionato, Kevin Peikert, Andreas Hermann, Adrian Danek, Kai van Bentum, Hermann Eichler, Christian Wagner, Stephan Quint, and Lars Kaestner
    Erysense, a Lab-on-a-Chip-Based Point-of-Care Device to Evaluate Red Blood Cell Flow Properties With Multiple Clinical Applications
    Front. Physiol. , 2022, 13, 1-10
    DOI: 10.3389/fphys.2022.884690

Erysense® device and principle of measurement. (A) Image of the Erysense® device. (B) Representative images of a croissant-shaped and a slipper-shaped RBC at low (1 mm/s) and high (10 mm/s) velocity, respectively. Scale bars represent 5 µm. Flow is from left to right and the dashed white line indicates the channel centerline in the y-direction with a channel width W. (C) Representative histograms and probability density functions (pdf) of the normalized cell’s center-of-mass in y-direction at a low (1 mm/s) and high (10 mm/s) velocity. (D) Representative shape phase diagram of a healthy control showing croissant-like, slipper-like, and other RBC shapes as a function of the cell velocity.
Erysense® device and principle of measurement.

  • Greta Simionato, Antonia Rabe, Joan Sebastián Gallego-Murillo, Carmen van der Zwaan, Arie Johan Hoogendijk, Maartje van den Biggelaar, Giampaolo Minetti, Anna Bogdanova, Heimo Mairbäurl, Christian Wagner, Lars Kaestner, and Emile van den Akker
    In Vitro Erythropoiesis at Different pO2 Induces Adaptations That Are Independent of Prior Systemic Exposure to Hypoxia
    Cells , 2022, 11, 1082
    DOI: 10.3390/cells11071082

Hemoglobin expression is increased at onset of erythroblast differentiation with a changed globin composition. (A) Quantification of Hb levels determined by spectrophotometry showed a significant increase at day 0 for cells at 3% O2. (B) HPLC analysis of hemoglobins at the end of differentiation (day 13). HbF expression was doubled in cells at 3% O2, reflected by a lower expression of HbA1. Moreover, HbA2 expression was retained in cultures performed at 3% O2. (C) Cytospins showed formed reticulocytes at 3% O2 at day 0, when cells were still suspended in the expansion medium. Occasional orthochromatic erythroblasts were found in 20% O2 and 20% O2 JJ cultures. (D) Statistical analysis on such images revealed a higher number of formed reticulocytes at day 0 and day 6 differentiation on a count of about 300 cells per volunteer. (E) No differences were found between 20% O2 and 20% O2 JJ.
Hemoglobin expression is increased at onset of erythroblast differentiation with a changed globin composition.

  • Daniel Flormann, Min Qiao, Nicoletta Murciano, Giulia Iacono, Alexis Darras, Sebastian Hof, Steffen M. Recktenwald, Maria Giustina Rotordam, Nadine Becker, Jürgen Geisel, Christian Wagner, Marieke von Lindern, Emile van den Akker, and Lars Kaestner
    Transient receptor potential channel vanilloid type 2 in red cells of cannabis consumer
    Am J Hematol. , 2022,
    DOI: 10.1002/ajh.26509

 Confocal images of RBCs stained deep red with cell mask in a HEPES-buffered solution of a 29-year-old male proband, who is a regular marijuana smoker. (A) Under control conditions the sample presents mainly discocytes as expected. (B) After stimulation with 30μM Δ9-THC, the RBCs showed considerable swelling. The light gray arrowheads indicate cells of the large fraction of super-hydrated spherocytes and the dark arrowheads indicate stomatocytes.
Confocal images of RBCs stained deep red with cell mask.

  • Mattia Cenedese, Joar Axås, Bastian Bäuerlein, Kerstin Avila, and George Haller
    Data-driven modeling and prediction of non-linearizable dynamics via spectral submanifolds
    Nat Commun , 2022, 13 872
    DOI: 10.1038/s41467-022-28518-y

 Data-driven nonlinear reduced-order model on the slowest SSM of fluid sloshing in a tank. (a) Setup for the sloshing experiment. (b) Decaying model-testing trajectory and its reconstruction from an unforced, SSM-based model (c) The geometry of the embedded SSM (d) Nonlinear damping α(ρ) from the SSM-reduced dynamics (e), (f) Closed form, SSM-based predictions of the FRCs and the response phases ψ0 for three different forcing amplitudes (solid lines), with their experimental confirmation superimposed (dots).
Data-driven nonlinear reduced-order model on the slowest SSM of fluid sloshing in a tank.

  • Alexis Darras, Anil Kumar Dasanna, Thomas John, Gerhard Gompper, Lars Kaestner, Dmitry A. Fedosov, and Christian Wagner
    Erythrocyte Sedimentation: Collapse of a High-Volume-Fraction Soft-Particle Gel
    Phys. Rev. Lett. , 2022, 128, 088101
    DOI: 10.1103/PhysRevLett.128.088101

 Measurements of relative height reduction of the dense erythrocyte suspension below the free liquid phase (plasma), for various hematocrits. Note that Δh corresponds to the height of top plasma layer.
Measurements of relative height reduction of the dense erythrocyte suspension.

  • Anil Kumar Dasanna, Alexis Darras, Thomas John, Gerhard Gompper, Lars Kaestner, Christian Wagner, and Dmitry A. Fedosov
    Erythrocyte sedimentation: Effect of aggregation energy on gel structure during collapse
    Phys. Rev. E , 2022, 105, 024610
    DOI: 10.1103/PhysRevE.105.024610

 ESR experiments. Cuvettes containing blood samples with various levels of fibrinogen are shown after 2 hours at rest. Hematocrit (i.e., erythrocyte volume fraction) in all containers has been adjusted to φ = 0.45. The very left container corresponds to erythrocytes suspended in autologous serum (no fibrinogen), while the very right contains erythrocytes in autologous blood plasma (maximum amount of fibrinogen). Middle containers contain cells suspended in a mixture of serum and plasma, with volume proportions of 25%, 50%, and 75% of plasma, from left to right.
Cuvettes containing blood samples with various levels of fibrinogen are shown after 2 hours at rest.

  • Alexis Darras, Hans Georg Breunig, Thomas John, Renping Zhao, Johannes Koch, Carsten Kummerow, Karsten König, Christian Wagner, and Lars Kaestner
    Imaging Erythrocyte Sedimentation in Whole Blood
    Front. Physiol. , 2022, 12, 729191
    DOI: 10.3389/fphys.2021.729191

 Light-sheet microscopy. (A) Scheme of the setup. The position of the taken pictures and the location of the reconstructed are also represented. (B) Picture of the device. One can see the opening (a) through which the samples are introduced in (b) the microscopy chamber, filled with water through the neighboring pipes. (C) Zoom on the microscopy chamber, containing (c) the sample, and surrounded by (d) the lenses focusing the laser into vertical sheets. The objective is seen behind the sample. (D) Raw picture as obtained during the experiment. (E) Reconstructed picture obtained after postprocessing of a z-stack. This stack was obtained after 90 min sedimentation time of the sample. The brightness of each pixel is created by the fluorescence of the plasma, erythrocytes are then present in the black areas.
Light-sheet microscopy.

  • Steffen M. Recktenwald, Katharina Graessel, Felix M. Maurer, Thomas John, Stephan Gekle, and Christian Wagner
    Red blood cell shape transitions and dynamics in time-dependent capillary flows
    Biophys. J , 2022, 121, 23-36
    DOI: 10.1016/j.bpj.2021.12.009

 Dynamics of single RBCs in time-dependent flows for (a) an experiment and (b) a simulation. The left and right columns in (a) and (b) correspond to upward and downward ramps, respectively. The bottom panels in (a) and (b) show the y coordinate of the cell's center of mass. The inset images show the cells at the start and end points of the shape transitions, highlighted by the magenta markers. The horizontal, dashed black lines correspond to the channel center axis. The scale bars represent a length of 5 μm.
Dynamics of single RBCs in time-dependent flows for an experiment and a simulation.

2021

  • Greta Simionato, Konrad Hinkelmann, Revaz Chachanidze, Paola Bianchi, Elisa Fermo, Richard van Wijk, Marc Leonetti, Christian Wagner, Lars Kaestner, and Stephan Quint
    Red blood cell phenotyping from 3D confocal images using artificial neural networks
    PLoS Comput Biol, 2021, 17, e1008934
    DOI: 10.1371/journal.pcbi.1008934

 (A) After sample staining and imaging by confocal microscopy, each cell is cropped individually and the full stack is interpolated in the z direction to achieve isotropic resolution (B). (C) The isosurface is retrieved by applying a constant threshold to each cell.
Workflow for automatic classification by the dual-stage ANN.

  • George H. Choueiri, Jose M. Lopez, Atul Varshney, Sarath Sankar, and Björn Hof
    Experimental observation of the origin and structure of elastoinertial turbulence
    PNAS, 2021, 118, e2102350118
    DOI: 10.1073/pnas.2102350118

Fluctuations level and flow structure near the onset of elastoinertial instability. (A) Evolution of the pressure fluctuations amplitude with increasing Re close to the instability threshold for experiments using 600 ppm of PAAm dissolved in a 50% water glycerol mixture. (B) Flow structures composition at Reynolds numbers near transition. Top and Middle show streamwise velocity fluctuations obtained from PIV measurements in a longitudinal cross-section. Lower shows the most unstable mode in the linear stability analysis..
Fluctuations level and flow structure near the onset of elastoinertial instability.

  • Clément Bielinski, Othmane Aouane, Jens Harting, and Badr Kaoui
    Squeezing multiple soft particles into a constriction: Transition to cloggings
    Phys. Rev. E , 2021, 104, 065101
    DOI: 10.1103/PhysRevE.104.065101

 Numerical setup used to study the flow of capsules (orange-colored spheres). The microfluidic constriction forms an angle of 90° with the channel walls. The flow direction is from the left lower preconstriction chamber to the right upper postconstriction chamber.
Numerical setup used to study the flow of capsules.

  • M. Wouters, O. Aouane, M. Sega, and J. Harting
    Lattice Boltzmann simulations of drying suspensions of soft particles
    Philos. Trans. R. Soc. A Math. Phys. Eng. Sci. , 2021, 379, 20200399
    DOI: 10.1098/rsta.2020.0399

 Snapshot of a simulation of 4806 particles. The boundary elements of the particles are coloured according to their height. For clarity, the fluid-fluid interface is not shown.
Snapshot of a simulation of 4806 particles.

  • Evgeny S. Asmolov, Tatiana V. Nizkaya1, Jens Harting, and Olga I. Vinogradova
    Instability of particle inertial migration in shear flow
    Phys. Fluids , 2021, 33, 092008
    DOI: 10.1063/5.0063566

 (a) Sketch of the particle motion in a shear flow. A particle translating across the streamlines experiences a transverse drag and a lift force. (b) Particle velocity in a neutral equilibrium.
Sketch of the particle motion in a shear flow.

  • Daniel Feldmann, Daniel Morón, and Marc Avila
    Spatiotemporal Intermittency in Pulsatile Pipe Flow
    Entropy, 2021, 23, 46
    DOI: 10.3390/e23010046

 Instantaneous representation of localised turbulent structures in a pulsatile pipe flow DNS at (Re=2400, Wo=8, A=1.4). The DNS was initialised at t/T=0.25 using the corresponding SW profile and by introducing a local bump like body force. Grey surfaces represent low-speed streaks and blue/red surfaces represent positive/negative axial vorticity. (a–d) Local bump. (e–h) Tilted bump. The direction of the mean bulk flow is always from left to right.
Instantaneous representation of localised turbulent structures in a pulsatile pipe flow.

  • Steffen M. Recktenwald, Christian Wagner, and Thomas John
    Optimizing pressure-driven pulsatile flows in microfluidic devices
    Lab Chip, 2021, 14, 4680-4687
    DOI: 10.1039/D0LC01297A

 (a) Schematic representation of the microfluidic setup. The feedback control system consists of the pressure controller and sensor, the tubing, the sample containers, and the microfluidic chip. The effect of the optimization approach is schematically shown in (b). While the non-optimized device output pressure deviates from the desired waveform (top), the optimization approach enhances the time-dependent pressure output and hence the flow velocity in the microfluidic chip (bottom).
Schematic representation of the microfluidic setup and the effect of the optimization approach.

  • Alexis Darras, Kevin Peikert, Antonia Rabe, François Yaya, Greta Simionato, Thomas John, Anil Kumar Dasanna, Semen Buvalyy, Jürgen Geisel, Andreas Hermann, Dmitry A. Fedosov, Adrian Danek, Christian Wagner, and Lars Kaestner
    Acanthocyte Sedimentation Rate as a Diagnostic Biomarker for Neuroacanthocytosis Syndromes: Experimental Evidence and Physical Justification
    Cells, 2021, 10, 788
    DOI: 10.3390/cells10040788

 Comparison of the erythrocyte sedimentation rate (ESR) between neuroacanthocytosis patients and healthy controls. ESR measurement setup: Standard Westergren tubes were filled with full blood and left to rest. The sedimentation height was measured over time. The picture was taken after 2 h. The first two tubes contain blood from an MLS patient, and the last two tubes contain blood from a healthy control donor.
Comparison of the erythrocyte sedimentation rate (ESR) between neuroacanthocytosis patients and healthy controls.

  • Christian Bächer, Diana Khoromskaia, Guillaume Salbreux, and Stephan Gekle
    A Three-Dimensional Numerical Model of an Active Cell Cortex in the Viscous Limit
    Front. Phys., 2021, 9, 753230
    DOI: 10.3389/fphy.2021.753230

 Dynamically deforming viscous active cortex. (A) The active surface stress is shown color coded on the initially spherical, discrete cortex. Towards the equator the isotropic active surface stress increases. (B) Resulting velocity profile on the initial cortex and (C) velocity after the cortex has reached its final shape where the normal velocity vanishes.
Dynamically deforming viscous active cortex.

  • Antonia Rabe, Alexander Kihm, Alexis Darras, Kevin Peikert, Greta Simionato, Anil Kumar Dasanna, Hannes Glaß, Jürgen Geisel, Stephan Quint, Adrian Danek, Christian Wagner, Dmitry A. Fedosov, Andreas Hermann, and Lars Kaestner
    The Erythrocyte Sedimentation Rate and Its Relation to Cell Shape and Rigidity of Red Blood Cells from Chorea-Acanthocytosis Patients in an Off-Label Treatment with Dasatinib
    Biomolecules, 2021, 11, 727
    DOI: 10.3390/biom11050727

 Measurements of the ESR with the standard Westergren method using EDTA blood. (A) Plots of the color-coded sedimentation curves retrieved from optical images taken every minute, i.e., the density of the data points corresponds approximately to the printed resolution.
Measurements of the ESR with the standard Westergren method using EDTA blood.

  • Pascal Corso, Jonas Walheim, Hannes Dillinger, George Giannakopoulos, Utku Gülan, Christos Emmanouil Frouzakis, Sebastian Kozerke, and Markus Holzner
    Toward an accurate estimation of wall shear stress from 4D flow magnetic resonance downstream of a severe stenosis
    Magn Reson Med., 2021, 00, 1– 13
    DOI: 10.1002/mrm.28795

 Magnitude of wall shear stress from the posterior view obtained A, from DNS complemented with the arrow representation of the WSS vector at the aorta wall; B, from MRI data using the direct and formal definition of WSS; C, using the first model M1 for the evaluation from MRI measurements; D, using the second model M2 for the MRI-based assessment.
Magnitude of wall shear stress from the posterior view.

  • Greta Simionato, Richard van Wijk, Stephan Quint, Christian Wagner, Paola Bianchi, and Lars Kaestner
    Rare Anemias: Are Their Names Just Smoke and Mirrors?
    Front. Physiol., 2021, 12, 690604
    DOI: 10.3389/fphys.2021.690604

 Investigation of hereditary spherocytosis red blood cell shapes. Three patients diagnosed with hereditary spherocytosis caused by different mutations (panels A–C) showed a spherocyte count of 11% (A), 8% (B), and 10% (C) in their stained peripheral blood smears, as exemplified in panel A (arrows, objective-magnification 100x). Comparison with 3D-rendered confocal recordings (objective-magnification 60x) of glutaraldehyde fixed and CellMask stained cells, however, demonstrated a different percentage of “true spherocytes”: 2.5% (A), 0% (B), and 0.08% (C). They are visualized in the dark colored boxes, each showing one cell from three perpendicular directions and mostly reflecting the amount observed in healthy subjects (0–0.3%, examined in 15 donors). In contrast, many cells look like spherocytes from one direction (leftmost view in all boxes) but the other faces reveal different morphologies, such as mushroom-shaped cells, stomatocytes or other irregular-shaped cells (all light colored boxes) representing “pseudo spherocytes.” These observations could be confirmed in 10 hereditary spherocytosis patients after 3D-imaging of about 1,000 cells per subject.
Investigation of hereditary spherocytosis red blood cell shapes.

  • Othmane Aouane, Andrea Scagliarini, and Jens Harting
    Structure and rheology of suspensions of spherical strain-hardening capsules
    J. Fluid Mech., 2021, 911, A11
    DOI: 10.1017/jfm.2020.1040

 Relative viscosity as a function of the effective volume fraction. The dashed and dotted lines corresponds to fits of the numerical data.
Relative viscosity as a function of the effective volume fraction. The dashed and dotted lines corresponds to fits of the numerical data.

  • François Yaya, Johannes Römer, Achim Guckenberger, Thomas John, Stephan Gekle, Thomas Podgorski, and Christian Wagner
    Vortical Flow Structures Induced by Red Blood Cells in Capillaries
    Microcirculation, 2021, 28 e12693
    DOI: 10.1111/micc.12693

 3D view showing the provenance (blue arrow) of the tracers and their trajectories for a cell velocity of 2.2 mm/s.
3D view showing the provenance (blue arrow) of the tracers and their trajectories for a cell velocity of 2.2 mm/s.

  • Bastian Bäuerlein, and Kerstin Avila
    Phase lag predicts nonlinear response maxima in liquid-sloshing experiments
    J. Fluid Mech., 2021, 925 A22
    DOI: 10.1017/jfm.2021.576

 Sketch of the experiment. A motor (a) drives an eccentric disk which converts the rotary motion of the motor via a pushing rod (b) into a quasi-harmonic horizontal oscillation of the platform. A positioning sensor (c) directly records the motion of the platform on which the tank (d), two high speed cameras (e) and a USB-camera (f) are mounted. For the particle image velocimetry measurements a light sheet (g) is provided by a laser passing through a cylinder lens (implemented in the stationary laser guiding arm).
Sketch of the liquid-sloshing experiment.

  • Alexander Kihm, Stephan Quint, Matthias W. Laschke, Michael D. Menger, Thomas John, Lars Kaestner, and Christian Wagner
    Lingering Dynamics in Microvascular Blood Flow
    Biophysj, 2021, 4, 1-8
    DOI: 10.1016/j.bpj.2020.12.012

 Probability density functions of scaled void durations for all branches if only lingering events are taken into account. The inset graph shows both the probability densities in the case of lingering and nonlingering, respectively to represent extreme cases of the median shift.
Probability density functions of scaled void durations for all branches if only lingering events are taken into account. The inset graph shows both the probability densities in the case of lingering and nonlingering, respectively to represent extreme cases of the median shift.

  • Julie Martin-Wortham, Steffen M. Recktenwald, Marcelle G. M. Lopes, Lars Kaestner, Christian Wagner, and Stephan Quint
    A deep learning-based concept for high throughput image flow cytometry
    Appl. Phys. Lett., 2021, 118, 123701
    DOI: 10.1063/5.0037336

 Single cells in a microfluidic channel are passing the optical detection zone. In the simulated setup, the cells are illuminated by a collimated light source and the transmitted light is modulated by a binary amplitude mask that is placed in between the channel and a simple light sensor.
Single cells in a microfluidic channel are passing the optical detection zone.

  • Duo Xu, Baofang Song, and Marc Avila
    Non-modal transient growth of disturbances in pulsatile and oscillatory pipe flows
    J. Fluid Mech., 2021, 907, R5
    DOI: 10.1017/jfm.2020.940

 Contours of stream-wise vorticity (on an r-θ cross-section) of the helical disturbance at t<sub>0</sub>/T = 0.5.
Contours of stream-wise vorticity (on an r-θ cross-section) of the helical disturbance at t0/T = 0.5.

  • Katharina Graessel, Christian Bächer, and Stephan Gekle
    Rayleigh–Plateau instability of anisotropic interfaces. Part 1. An analytical and numerical study of fluid interfaces
    J. Fluid Mech,, 2021, 910, A46
    DOI: 10.1017/jfm.2020.947

 Illustration of the set-up. We consider a complex interface which can be either a liquid jet of Newtonian fluid in the limit of vanishing viscosity η or the membrane of a vesicle or cell immersed in a fluid in the limit of the Stokes equation, i.e. density ρ=0 . The fluid jet is immersed in an ambient fluid with η<sub>0</sub>,ρ<sub>0</sub> . The cylindrical interface of initial radius R<sub>0</sub> (dashed line) is subjected to a periodic perturbation with amplitude ϵ (solid blue line). The interface is parametrised by the position along the cylinder axis z and the radius R(z,t) . We consider the interfacial tension in the axial direction (orange) different from that in the azimuthal direction (green), both of which contribute to the membrane force acting onto the fluid with different curvature components (grey circles).
Illustration of the set-up; Rayleigh–Plateau instability.

2020

  • Maarten Wouters, Othmane Aouane, Marcello Sega, and Jens Harting
    Capillary interactions between soft capsules protruding through thin fluid films
    Soft Matter, 2020, 16, 10910–10920
    DOI: 10.1039/d0sm01385d

 Time evolution of the gap between two soft particles: (solid line) β = 10, (dashed line) β = 25, (dot-dashed line) β = 50. The grey area indicates the repulsive region. Inset: Final state of two particles with β = 50 (solid lines) at the interface (dashed line).
Time evolution of the gap between two soft particles: (solid line) β = 10, (dashed line) β = 25, (dot-dashed line) β = 50. The grey area indicates the repulsive region.

  • Moritz Lehmann, Sebastian Johannes Müller, and Stephan Gekle
    Efficient viscosity contrast calculation for blood flow simulations using the lattice Boltzmann method
    Int. J. Numer. Methods Fluids, 2020, 92, 1463–1477
    DOI: 10.1002/fld.4835

 The center of mass radial displacement averaged over the last 0.2 seconds for different values of 𝜆. Lattice Boltzmann method with our inside/outside tracking and local viscosity change reproduces the 𝜆-phase-transition from boundary-integral simulations quite accurately.
The center of mass radial displacement averaged over the last 0.2 seconds for different values of 𝜆.

  • Duo Xu, Matthias Heil, Thomas Seeböck, and Marc Avila
    Resonances in Pulsatile Channel Flow with an Elastic Wall
    Phys. Rev. Lett., 2020, 125, 254501
    DOI: 10.1103/PhysRevLett.125.254501

 (a),(b) Sketch of the model. (c) Oscillation amplitude, where the solid and the dashed lines denote the viscous and the inviscid prediction, and black and blue correspond to β = 0.25 and β = 0. The black symbols show the results from the simulations. The dotted lines mark the corresponding eigenfrequencies.
(a),(b) Sketch of the model. (c) Oscillation amplitude, where the solid and the dashed lines denote the viscous and the inviscid prediction, and black and blue correspond to β = 0.25 and β = 0. The black symbols show the results from the simulations. The dotted lines mark the corresponding eigenfrequencies.

  • Tatiana V. Nizkaya, Evgeny S. Asmolov, Jens Harting, and Olga I. Vinogradova
    Inertial migration of neutrally buoyant particles in superhydrophobic channels
    Phys. Rev. Fluids, 2020, 5, 014201
    DOI: 10.1103/PhysRevFluids.5.014201

 Sketch of the system: side (a) and top (b) views, with a schematic of vertical and transverse migration.
Sketch of the system: side (a) and top (b) views, with a schematic of vertical and transverse migration.

  • Tatiana V. Nizkaya1, Anna S. Gekova, Jens Harting, Evgeny S. Asmolov, and Olga I. Vinogradova
    Inertial migration of oblate spheroids in a plane channel
    Phys. Fluids, 2020, 32, 112017
    DOI: 10.1063/5.0028353

 An oblate spheroid orienting in a pressure-driven flow to perform a stable log-rolling state.
An oblate spheroid orienting in a pressure-driven flow to perform a stable log-rolling state.

  • Duo Xu, Atul Varshney, Xingyu Ma, Baofang Song, Michael Riedl, Marc Avila, and Björn Hof
    Nonlinear hydrodynamic instability and turbulence in pulsatile flow
    PNAS, 2020, 117, 11233–11239
    DOI: 10.1073/pnas.1913716117

 Visualization of the numerical simulation of a turbulent blood stream.
Visualization of the numerical simulation of a turbulent blood stream.

  • Asena Abay, Steffen M. Recktenwald, Thomas John, Lars Kaestner, and Christian Wagner
    Cross-sectional focusing of red blood cells in a constricted microfluidic channel
    Soft Matter, 2020,16, 534-543
    DOI: 10.1039/C9SM01740B

 Schematic representation of red blood cells (RBCs) flowing through a contraction–expansion microfluidic device. Passing the contraction, RBCs are mainly focused in two lines near the shorter faces in the channel center plane (z = 0 and y/W ≈ ±0.4) and at the top and bottom of the channel near the walls (z/H ≈ ±0.3 and −0.4 ≤ y/W ≤ 0.4).
Schematic representation of red blood cells flowing through a contraction–expansion microfluidic device.



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