The European Physical Journal E最新文献

{"title":"Inertial forces and elastohydrodynamic interaction of spherical particles in wall-bounded sedimentation experiments at low (textit{Re}_textrm{P})","authors":"Isabell Noichl,&nbsp;Clarissa Schönecker","doi":"10.1140/epje/s10189-026-00594-8","DOIUrl":"10.1140/epje/s10189-026-00594-8","url":null,"abstract":"<p>Unsteady, wall-bounded sedimentation of spheres at low particle Reynolds numbers, Re<span>(_textrm{P}lesssim 0.1)</span>, under the influence of small elastic deformation was investigated experimentally. The complete kinematics of elastic and rigid spheres sedimenting from rest at various initial distances from a rigid plane wall in a rectangular duct were measured. Several previously unrecognized phenomena arising from fluid inertia and superimposed elastohydrodynamic effects were identified and analyzed. Among these is an <i>inertial wall attraction</i>, whereby particles migrate toward the wall during the initial acceleration phase. After this initial phase, rigid spheres sedimenting at Re<span>(_textrm{P}approx O(10^{-1}))</span> followed behavior consistent with classic wall-lift models, including approximately linear migration away from the wall. In contrast, at smaller Reynolds numbers, Re<span>(_textrm{P}approx O(10^{-2}))</span>, both rigid and elastic spheres exhibited persistently unsteady sedimentation, characterized by deceleration despite increasing wall distance. These results enable the formulation of a conceptual framework that classifies near-wall sedimentation regimes according to particle Reynolds number and the position of boundaries relative to the Stokes length scale. For increasing deformability, the unsteady behavior was further modulated by nonlinearities. The observations suggest the presence of an <i>elastohydrodynamic memory</i> effect arising from the coupling of fluid inertial forces with particle deformability. The experimental findings are supported by computational fluid dynamics simulations that provide qualitative insight into the evolving flow field. Overall, the results demonstrate that classic assumptions commonly applied to particle sedimentation in creeping flows break down in the presence of nearby boundaries and reveal a counterintuitive trend: as the particle Reynolds number decreases, fluid inertia can play an increasingly important role in governing particle motion near walls. The proposed conceptual framework may therefore aid the interpretation of the near-wall dynamics of deformable microplastic particles, for which comparable material properties and flow regimes are encountered in environmental and wastewater flows.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00594-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148300523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Avalanches in the random organization model with long-range interactions","authors":"Tristan Jocteur,&nbsp;Kirsten Martens,&nbsp;Romain Mari,&nbsp;Eric Bertin","doi":"10.1140/epje/s10189-026-00599-3","DOIUrl":"10.1140/epje/s10189-026-00599-3","url":null,"abstract":"<p>Oscillatory sheared suspensions, when observed stroboscopically, exhibit a reversible–irreversible transition as a function of the strain amplitude, which is an absorbing phase transition, separating diffusive states on the irreversible side from absorbing states on the reversible side. So far studies of this transition focused on global quantities, e.g., quantifying the irreversibility on the one side of the transition or the time to reach a reversible state on the other side. Here, inspired by depinning-type transitions, we focus on intermittent dynamics close to the transition. We perform simulations of a modified Random Organization Model (ROM), a minimal particle model which we recently adapted to take into account the generic presence of long-range interactions mediated by the fluid, taking the power-law decay exponent <span>(alpha )</span> as an additional control parameter of the model. We show that at the absorbing phase transition, this model displays power-law distributed avalanches. We characterize the avalanche statistics in terms of avalanche size, duration and number of particles involved, and we determine the associated exponents. By varying the exponent <span>(alpha )</span>, the fractal dimension of avalanches crosses space dimension <i>d</i>, inducing a qualitative change of the spatial structure of avalanches, from compact avalanches when interactions have a short range, to sparse avalanches when interactions are long-ranged. Finally, we characterize the clusters within the avalanches, which we also find to be power-law distributed.</p><p>Spacetime plots of avalanches of irreversible events (in red) in presence of mediated mechanical noise. Left: long-ranged mechanical noise leads to sparse avalanches. Right: short-ranged mechanical noise leads to compact avalanches.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148281827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Semi-analytical modeling and simulation of human red blood cell deformation under non-linear strain","authors":"Gaurav D. Bhabhor,&nbsp;Rishabh Bhatt,&nbsp;Arun Anand,&nbsp;Kirit N. Lad","doi":"10.1140/epje/s10189-026-00601-y","DOIUrl":"10.1140/epje/s10189-026-00601-y","url":null,"abstract":"<div><p>The study of red blood cell (RBC) deformability remains an active area of research due to its linkage to health and normal physiological functions of RBCs in the circulatory system. RBC deformability is commonly analyzed using force-based experimental and theoretical approaches. Complementary to these methods, geometric descriptions of RBC shape provide insight into curvature redistribution and bending energetics independent of explicit constitutive modeling. In this work, we present a semi-analytical, surface-based framework to study RBC deformation under axial stretching by imposing an affine geometric strain on a triangulated biconcave membrane, with volume conservation enforced throughout. Linear strain and a non-linear Hencky-type strain are compared. While linear strain reproduces experimental trends only for small deformations, nonlinear strain yields global shape variations—axial and transverse diameters and elongation index—that are consistent with reported optical tweezers data over a wide deformation range. The surface formulation enables detailed mapping of Gaussian and mean curvature redistribution during elongation. Evaluation of the Helfrich bending energy, including spontaneous curvature treated as an effective geometric parameter, yields energetically consistent values when non-linear strain is employed. Analysis of the curvature-bending energy of the RBC subjected to axial stretching suggests that nonlinear strain and spontaneous curvature should be the primary considerations to ensure that the membrane bending energy remains within the range of 10–100 eV during RBC biomechanical deformation. The framework does not resolve force balance or membrane constitutive behavior, but provides a computationally efficient geometric surrogate linking imposed deformation to curvature and bending energetics.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div><div><p>Geometrical affine deformation of RBC under non-linear strain</p></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148292946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vector nematodynamics with symmetry-driven energy exchange","authors":"L. M. Pismen","doi":"10.1140/epje/s10189-026-00600-z","DOIUrl":"10.1140/epje/s10189-026-00600-z","url":null,"abstract":"<p>We review inadequacy of existing nematodynamic theories based on Onsager’s near-equilibrium relations and suggest a novel way of establishing relations between nematic orientation and flow, based on the <i>local</i> symmetry between simultaneous rotation of nematic alignment and flow, which establishes energy and momentum exchange between the two without reducing the problem to near-equilibrium conditions. This approach, applied in the framework of the vector-based theory with a variable modulus, involves antisymmetric interactions between nematic alignment and flow. It avoids spurious instabilities in the absence of active inputs and elucidates their cause.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 7","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00600-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148261774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Drop volume effect on the advancing macroscopic contact angle","authors":"Roudy Issa,&nbsp;Houssine Benabdelhalim,&nbsp;Marc Medale,&nbsp;David Brutin","doi":"10.1140/epje/s10189-026-00577-9","DOIUrl":"10.1140/epje/s10189-026-00577-9","url":null,"abstract":"<p>We investigate the influence of drop volume on partial wetting of sessile drops on a horizontal solid substrate for up to large Bond numbers, considering water on both polymethyl methacrylate (PMMA) and aluminum-coated substrates, as well as glycerol on PMMA. The horizontal orientation of the substrate, along with methods for creating sessile drops, facilitated the rotational symmetry of drops to perform controlled and reproducible experiments. In particular, we explore the manner in which the statistic macroscopic contact angle (MCA) depends on the sessile drop volume or related Bond numbers, whether the drop is injected via a syringe positioned above the substrate (DSA30 Krüss equipment) or from below the substrate through a tiny hole drilled in it. In both cases, experimental results exhibit that as the drop volume is increased spanning Bond numbers in the range [0.1–14], the contact line advances on the substrate and the MCA significantly decreases down to an asymptotic value.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148148050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Giant nonequilibrium fluctuations in dilute and semidilute polymer solutions subjected to large temperature gradients","authors":"J. Kantelhardt,&nbsp;D. Zapf,&nbsp;W. Köhler","doi":"10.1140/epje/s10189-026-00591-x","DOIUrl":"10.1140/epje/s10189-026-00591-x","url":null,"abstract":"<p>Shadowgraph experiments have been performed on giant nonequilibrium fluctuations in solutions of polystyrene in toluene with polymer molar masses between 2.1 and 90.9 kg/mol and mass fractions ranging from 0.002 up to 0.6. Due to the large Soret coefficient of the polymer and the applied temperature difference of 50 K, a linear model is not sufficient to describe the time-dependent and static structure functions. Nonlinearities stemming mainly from the highly nonlinear concentration profile, as well as from the temperature and concentration dependence of various thermophysical parameters, are taken into account using a previously developed layer model. This model enables a detailed analysis of the signal generation within the shadowgraph cell. The thermal structure function mainly emerges from the hot top plate. For short polymer chains and/or low concentrations, the solutal structure function is dominated by the cold side. However, due to the complicated interplay between the Soret effect, the viscosity, and the gravitational quench, this can change for long chains and high concentrations, with the strongest solutal signal emerging from the hot side. Situations involving a non-monotonous layer sequence are also possible. The simulated structure functions agree reasonably with experimental data.</p><p>Dispersion of the structure functions due to nonlinearities in strong temperature gradients</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00591-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148148052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study of the interference colors of the microscopic textures simulated along the lyotropic phase sequence: cholesteric discotic–cholesteric biaxial–unwound cholesteric calamitic","authors":"D. D. Lüders,&nbsp;E. Akpinar,&nbsp;G. E. Delmanoco","doi":"10.1140/epje/s10189-026-00593-9","DOIUrl":"10.1140/epje/s10189-026-00593-9","url":null,"abstract":"<div><p>The interference colors of the microscopic textures, observed under a polarized microscope for the oriented cholesteric discotic (Ch_D)–cholesteric biaxial (Ch_B)–unwound cholesteric calamitic (N_C^*) phases sequence in the presence of a magnetic field, were studied in this work. The referred textures were interpreted from both experimental and theoretical views. The lyotropic nematic host mixtures consisted of potassium laurate (KL), 1-undecanol (unDeOH), potassium sulphfate (K₂SO₄), and water (H₂O). The chiral guest molecule brucine was added to the host nematic mixture to induce the cholesteric phases. The refractive indices and birefringences of the lyotropic samples were measured along the nematic calamitic (N_C)–nematic biaxial (N_B)–nematic discotic (N_D) phases sequence as a function of temperature, and they were used to simulate the stripe textures of the oriented cholesteric phases, Ch_D and Ch_B, theoretically. It was shown that the experimental and simulated results are in good agreement with each other.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00593-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148136418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodiffusion and thermo-osmosis in thin membranes with slit pores","authors":"Bjørn Hafskjold,&nbsp;Signe Kjelstrup","doi":"10.1140/epje/s10189-026-00592-w","DOIUrl":"10.1140/epje/s10189-026-00592-w","url":null,"abstract":"<p>Waste heat sources are potentially useful for component separation in fluid mixtures. To better understand how thermal driving forces can contribute to separation, we have investigated the Soret balances of forces for thermodiffusion and thermo-osmosis. A set of two-component fluid isotope mixtures with mass ratio <span>(m_2/m_1)</span> has been investigated in membranes with molecular-sized pores. Numerical support generated by molecular dynamics simulations is achieved for two models; one for the Soret coefficient, <span>(S = a_m (m_2-m_1)/(m_2+m_1) + b_{varepsilon }(varepsilon _{2text {m}} -1))</span>, and one for the thermo-osmotic coefficient, <span>(D_{p} = a (Delta H/Delta T) + b)</span>, where <span>(varepsilon _{2text {m}})</span> is a parameter for the fluid–membrane interactions, <span>(Delta )</span> refers to a difference across the membrane, <i>H</i> is the bulk fluid enthalpy, and <i>T</i> is the temperature. In these formulas <span>(a_m, b_{varepsilon }, a, b)</span> are system-specific constants. The results apply to Lennard–Jones/spline isotope mixtures of mass ratios <span>(0.1&lt; (m_2/m_1) &lt; 10)</span>, with thermally insulating membrane materials, and component-specific fluid–pore interactions. The results give information about how the Soret balances depend on membrane properties, which potentially can be used to tailor membranes for efficient separation.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00592-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148136420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cruising and jumping: the effect of microplastics on the swimming behavior of copepods measured by 3D Lagrangian particle tracking velocimetry","authors":"F.-G. Michalec,&nbsp;O. Praud,&nbsp;M. Lorite-Diez,&nbsp;S. Cazin,&nbsp;S. Souissi,&nbsp;E. Climent","doi":"10.1140/epje/s10189-026-00587-7","DOIUrl":"10.1140/epje/s10189-026-00587-7","url":null,"abstract":"<p>Calanoid copepods are key components of marine and estuarine food webs. Exposure to various classes of pollutants induces changes in their swimming behavior. This raises concerns about potential effects on critical processes such as feeding, mating, predator avoidance and vertical migration. The effect of pollution by microplastics is not well known. We investigated in a large experimental tank the effects of the smallest size fraction of microplastics on the swimming behavior of the estuarine copepod <i>Eurytemora affinis</i>. Because the motion of zooplankton is intrinsically linked to that of the ambient fluid, we recorded copepods moving freely in calm water and in grid-generated turbulence to recreate some of the hydrodynamic conditions they experience in their natural environment. Using an advanced implementation of 3D Lagrangian particle tracking velocimetry, we simultaneously measured copepod trajectories and the surrounding flow field at high temporal resolution. In calm water, copepods alternated between periods of cruising and sudden relocation jumps. In turbulence, copepod motion was dominated by transport by the flow, yet jumps allowed copepods to deviate from the flow streamlines. The measurement of the relative velocity of copepods with respect to the underlying flow enabled us to characterize the statistics of these jumps. Turbulence significantly increased jump frequency without modifying their amplitude or duration. Following a 12-hour exposure to polyethylene fragments at 300 <span>(mu )</span>g/L, copepods showed increased jump frequency in calm water corresponding to 40 % increase in energetic cost. In contrast, exposure to microplastics produced weak additional effects on swimming behavior under turbulent conditions. These results confirm the existence of an active response to turbulence in <i>E. affinis</i> and are consistent with a hyperactive behavior triggered by exposure to microplastic pollution.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 6","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-026-00587-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148021069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the heat of formation of indium telluride via graph entropy descriptors and curve fitting techniques","authors":"Wakeel Ahmed,&nbsp;Amman Farzeen,&nbsp;Kashif Ali,&nbsp;Shahid Zaman,&nbsp;Asad Ullah","doi":"10.1140/epje/s10189-026-00588-6","DOIUrl":"10.1140/epje/s10189-026-00588-6","url":null,"abstract":"<div><p>This study presents an extensive graph-theoretic analysis of the thermodynamic properties of indium telluride (InTe). We analyze the significant relationship between the molecular structure of InTe and its macroscopic behavior through the application of graph entropy, a fundamental metric in information theory and statistical thermodynamics. In this framework, the chemical structure is depicted as a graph, with atoms as vertices and chemical bonds as edges. We calculate a set of topological indices for InTe, a material that is very useful in thermoelectrics, phase-change memory, and infrared optics. These indices encode the material’s structural connectivity in numbers. These indices are used to figure out a range of graph entropies, which measure how complex and information-rich the molecular lattice is. The main part of this work shows strong quantitative links between these graph entropies and important thermodynamic properties, such as heat capacity and heat of formation. We use suitable quadratic surface-fitting models that show exactly how these thermodynamic responses depend on pairs of graph entropies in a nonlinear way. All computational modeling and analysis are conducted to enhance statistical fit, guaranteeing that the chosen models deliver the most dependable predictive capability for comprehending and anticipating the material’s stability and thermal characteristics.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture><span>The alternative text for this image may have been generated using AI.</span></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"49 5","pages":""},"PeriodicalIF":2.2,"publicationDate":"2026-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147938358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}