Theoretical and Computational Fluid Dynamics最新文献

{"title":"Rheological fingerprints for a Bautista-Manero-Puig model-variant with Elasto-Visco-Plastic features under a true yield-stress approach","authors":"Michelle Figueroa-Landeta,&nbsp;Miguel Moyers-Gonzalez,&nbsp;Octavio Manero,&nbsp;J. Esteban López-Aguilar","doi":"10.1007/s00162-026-00781-5","DOIUrl":"10.1007/s00162-026-00781-5","url":null,"abstract":"<div><p>In this work, a new model-variant in the Bautista-Manero-Puig (BMP) model is proposed, with the peculiarity of providing true yield-stress features under vanishing deformation rates. This proposed model is devised to predict an Elasto-Visco-Plastic (EVP) rheological response through the assumption of a null fluidity (infinite viscosity) limit, and inherits the BMP ability to track the material-structure temporal evolution through a thixotropic kinetic equation. This new model, termed BMP-EVP, is systematically compared against the parent original BMP model, which provides solid-like features in an apparent yield-stress modality, through diminishing solvent fractions. The rheological fingerprints of both BMP and BMP-EVP models are exposed and contrasted under typical steady and transient rheometrical tests, under shearing and extensional deformations, alongside oscillatory protocols under Small and Large Angle Oscillatory Shear (SAOS and LAOS, respectively). Here, plasticity is measured through the definition of critical deformations for material fluidisation that appeared explicitly and directly correlated with the BMP thixotropic parameters. Conventional steady-state simple shear and uniaxial extensional flows render the BMP and BMP-EVP models comparable in their material-function predictive capabilities. In contrast, non-linear transient tests show attractive differences across these models, for which secondary loops in LAOS and non-monotonic stress-growth coefficient in start-up flows, evidence the interplay between the thixo-viscoelastic features of these models and their distinct plastic responses.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-026-00781-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147560536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Implementation of spectral difference method for solving discrete Boltzmann equation","authors":"Mohammad Abotalebi,&nbsp;Kazem Hejranfar","doi":"10.1007/s00162-026-00776-2","DOIUrl":"10.1007/s00162-026-00776-2","url":null,"abstract":"<div><p>In this study, the spectral difference method is implemented for the numerical solution of the discrete Boltzmann equation to provide a robust and high-order accurate compressible gas kinetic scheme for effectively computing compressible rarefied gas flows. To this aim, the discrete Boltzmann equation with the Shakhov model is considered and the spatial discretization in the resulting equation is performed by the spectral difference method and the fourth-order Runge-Kutta method is used for the temporal discretization. Different one- and two-dimensional test cases are simulated to examine the accuracy and performance of the present methodology based on the spectral difference solution of the Boltzmann equation (SDBE). At first, the two-dimensional incompressible flow problems, namely, the Taylor-Green vortex flow and the cavity flow are simulated by applying the third-order SDBE and the results obtained are compared with the analytical solution and the available gas-kinetic and direct simulation Monte Carlo (DSMC) results which exhibit good agreement. Then, some compressible flow problems including the one-dimensional Riemann shock tube, the one-dimensional normal shock structure and the supersonic flow over a cylinder problem are computed to better examine the accuracy and robustness of the present method by applying the SDBE in different conditions. To further assess the accuracy and performance of the third-order SDBE, the simulations are also performed by the third-order upwind finite-difference solution of the Boltzmann equation (UFDBE) and the results of these two numerical schemes are thoroughly compared with each other. It is indicated that the high-order gas kinetic scheme implemented based on the spectral difference solution of the Boltzmann equation (SDBE) can be applied for accurately and effectively computing rarefied gas flows in a wide range of Knudsen numbers.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147559990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Controlling droplet breakup and routing in microfluidic T-Junctions via wettability contrast","authors":"Mohanad Radhi,&nbsp;Derek Tretheway","doi":"10.1007/s00162-026-00779-z","DOIUrl":"10.1007/s00162-026-00779-z","url":null,"abstract":"<div><p>In this study, we investigate how the asymmetric wetting conditions affect the droplet dynamics in microfluidic T-junctions using a three-dimensional multicomponent lattice Boltzmann method based on the two-component Shan–Chen model. The model has been validated against theoretical and benchmark cases, including the Young–Laplace law and classical symmetric droplet breakup. Through a series of simulations, we have explored the effects of contact angle contrast, droplet length, capillary number, channel geometry, and viscosity ratio on the margins that split breakup and non-breakup regimes. The results demonstrate that spatial wettability asymmetry significantly alters droplet evolution, which promotes controlled redirection or suppression of breakup. Increasing the upper-lower contact angle difference promotes droplet steering toward the more wettable side, whereas higher capillary numbers and longer droplets tend to experience more breakup. Additionally, geometric parameters such as aspect ratio and side-to-main channel width ratio regulate the competition between surface and hydrodynamic forces, critically influencing droplet final state. The viscosity ratio affects the droplet dynamics in two ways: impacting internal recirculation and interfacial stress resistance. This work aims to provide a physics-based framework for passive droplet control by utilizing wettability engineering and geometrical design to offer practical insights for lab-on-a-chip devices and multiphase flow systems. Future work will incorporate non-Newtonian effects and dynamic wetting to extend applicability to more complex flow regimes.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147335923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"CLIP: A CUDA-Accelerated lattice boltzmann framework for interfacial phenomena with application to liquid jet simulations","authors":"Mehdi Shadkhah,&nbsp;Mohammad Taeibi Rahni,&nbsp;Azadeh Kebriaee,&nbsp;Mohammad Reza Salimi","doi":"10.1007/s00162-026-00777-1","DOIUrl":"10.1007/s00162-026-00777-1","url":null,"abstract":"<div><p>This work introduces CLIP, a CUDA-accelerated phase-field lattice Boltzmann framework for simulating immiscible two-phase flows with high density and viscosity ratios in both two- and three-dimensional domains. By leveraging GPU parallelism, the framework delivers substantial computational speedups, enabling large-scale simulations to be performed efficiently on standard desktop hardware without the need for high-performance computing clusters. It employs the Weighted Multi-Relaxation Time (WMRT) collision operator to enhance numerical stability and improve interface tracking under challenging multiphase conditions. The model is validated through a series of benchmark cases, including capillary wave dynamics, stationary drop tests, two-phase Poiseuille flow, shear-driven interface deformation, and Rayleigh–Taylor instability. It is further applied to simulate liquid jet breakup, capturing the transition from dripping to jetting regimes and identifying a critical Weber number of approximately 2.2. The results closely match experimental observations, offering detailed insights into breakup length, drop size distributions, and flow regime transitions. With its efficiency, accuracy, and scalability, the proposed framework serves as a powerful and accessible tool for investigating complex interfacial phenomena in multiphase flow physics.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147340092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Curvature-dependent area preserving immersed boundary method for binary immiscible fluids","authors":"Haobo Hua,&nbsp;Pu Han,&nbsp;Seunggyu Lee,&nbsp;Huan Han,&nbsp;Hyundong Kim,&nbsp;Junseok Kim","doi":"10.1007/s00162-026-00778-0","DOIUrl":"10.1007/s00162-026-00778-0","url":null,"abstract":"<div><p>We propose an immersed boundary method (IBM) with a curvature-dependent, area-preserving correction algorithm for binary immiscible incompressible fluid flows. The IBM was first proposed to solve biofluid dynamics in complex geometries, and researchers later used it for multiphase fluid flows due to its direct and simple representation of complex interfaces. In this method, two types of grids are needed: an Eulerian formulation for the computation of fluid flow and a Lagrangian representation for the movement of the immersed boundary. If the conventional method is used, area loss or area increases occur due to numerical discretization errors. In the proposed correction method, the positions of the Lagrangian interface points are adjusted along the normal direction in proportion to the local curvature. Numerical examples of droplet deformation under various flow conditions show that the proposed algorithm can discretely preserve the initial area while the interface undergoes large deformation.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147338620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The coherent structures of EVP fluid flow past a circular cylinder","authors":"Adrián Corrochano,&nbsp;Kazi Tassawar Iqbal,&nbsp;Saeed Parvar,&nbsp;Soledad Le Clainche,&nbsp;Outi Tammisola","doi":"10.1007/s00162-026-00775-3","DOIUrl":"10.1007/s00162-026-00775-3","url":null,"abstract":"<div><p>This study investigates the impact of elasticity and plasticity on two-dimensional flow past a circular cylinder at Reynolds number <span>(Re = 100)</span>. Ten direct numerical simulations were performed using the Saramito-Herschel–Bulkley model to represent viscoelastic and elastoviscoplastic (EVP) fluids. The flow evolves from a periodic von Kármán vortex street to chaotic-like regimes. Proper Orthogonal Decomposition (POD) and Higher Order Dynamic Mode Decomposition (HODMD) are applied to extract dominant flow structures and their temporal dynamics. For viscoelastic fluids, increasing the Weissenberg number <i>Wi</i> elongates the recirculation bubble and shifts it downstream, resulting in more intricate but still periodic behavior. In EVP fluids, seven cases explore variations in Bingham number <i>Bn</i>, solvent viscosity ratio <span>(beta _s)</span>, and power law index <i>n</i>, aiming to qualitatively assess their influence rather than determine critical thresholds. Results indicate that stronger plastic effects, especially with <span>(n ge 1)</span>, lead to increased flow complexity. Three dynamic regimes are identified: (i) periodic; (ii) transitional, with elongated recirculation and disrupted periodicity; and (iii) fully complex, with breakdown of recirculation. Overall, the study highlights the interplay between inertia, elasticity, and yield stress in non-Newtonian flows past obstacles and identifies key parameters driving the transition from periodic to complex regimes.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-026-00775-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145983272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Natural and mixed convection in a vertical rectangular duct under solar radiation","authors":"Milan Rashevski,&nbsp;Slavtcho Slavtchev","doi":"10.1007/s00162-025-00774-w","DOIUrl":"10.1007/s00162-025-00774-w","url":null,"abstract":"<div><p>The paper deals with natural and mixed convection in a vertical rectangular duct exposed to solar radiation. The physical problem under consideration describes flow and heat transfer processes in a water-filled glazing chamber irradiated from the side. Due to the absorption properties of water, the near-infrared irradiance initiates a non-uniform volumetric heat source described by the Beer-Lambert law. Based on the Navier-Stokes equations with Boussinesq approximation and the energy equation, a mathematical problem for well-developed viscous flows in a rectangular duct is formulated. New exact analytical solutions in series are obtained, which include terms accounting for the effect of the heat source. The influence of the duct aspect ratio on the temperature and velocity fields is evaluated. While natural convection flow is always reversible, in the case of combined free and forced convection, a condition for the appearance of flow reversal is derived. Hydrodynamic and thermal characteristics such as Fanning friction factor, bulk liquid temperature, and Nusselt numbers at the walls are determined. The influence of the lateral walls diminishes with the increase of the aspect ratio, and when the duct is sufficiently narrow, the thermal characteristics of the flow approach the corresponding values for a plane-parallel channel.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145983271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the swimming velocity of an inertial ellipsoidal microswimmer in a square tube","authors":"Tongxiao Jiang,&nbsp;Geng Guan,&nbsp;Yuxiang Ying,&nbsp;Jianzhong Lin","doi":"10.1007/s00162-025-00773-x","DOIUrl":"10.1007/s00162-025-00773-x","url":null,"abstract":"<div><p>We use three-dimensional numerical simulations based on the lattice Boltzmann method to study how an ellipsoidal microscopic swimmer moves through a square microchannel. Three key factors are varied: the strength of inertial effects in the flow, the swimmer’s shape (from spherical to three times longer than it is wide), and the degree of confinement by the channel walls (from narrow channels about three swimmer diameters across to wider channels about eight diameters). We consider both pushers (which drive the fluid backward with their rear end like sperm cells) and pullers (which pull the fluid forward with their front end like algae). As inertia increases, pushers swim faster whereas pullers slow down, and the change in speed is much stronger for pushers. The swimming speed can be captured by a simple quadratic trend when expressed in terms of a single combined measure of inertia and swimming stroke. More elongated swimmers move faster overall and are less influenced by inertia, while nearly spherical swimmers are the most sensitive to changes in inertia. As the channel becomes wider, the walls constrain the swimmer less, and variations in inertia have a more pronounced impact on the swimming speed.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145983141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the instabilities of a three-dimensional viscoplastic Rayleigh-Bénard convection","authors":"Marco A. Ferrari,&nbsp;Paulo R. M. Santos,&nbsp;Luiz A. Hegele,&nbsp;Admilson T. Franco","doi":"10.1007/s00162-025-00771-z","DOIUrl":"10.1007/s00162-025-00771-z","url":null,"abstract":"<div><p>Rayleigh-Bénard convection is a canonical problem in fluid mechanics, where an adverse temperature gradient between the opposing boundaries induces instabilities that drive natural convection. For viscoplastic fluids, a minimal perturbation is required to initiate the flow. This study presents a numerical investigation of the three-dimensional Rayleigh-Bénard convection within a cubic cavity heated from below, with lateral walls subject to a linear temperature profile. The fluid behavior is modeled using the Bingham constitutive model. The moment-based Lattice Boltzmann Method was employed as the numerical method to solve the mass and momentum transport equations, with an extended formulation to incorporate the energy transport equation using a local diffusion coefficient approach. Simulations are performed for Rayleigh numbers between 10⁴ and 10⁷. Within this range, we observed a region of Yield numbers, between 0.004 and 0.007, that fluid plastifies. Increasing the Rayleigh number led to a transition from a stationary to a chaotic state, while larger Prandtl numbers damped the fluctuations in the velocity field. Notably, the imposition of a linear temperature profile on the lateral boundaries enhances flow instability, thereby amplifying plastic instabilities as the critical Yield number is approached.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modelling rectangular-jet screech via dimensional reduction","authors":"Grant Lu,&nbsp;Jayson Beekman,&nbsp;Soudeh Mazharmanesh,&nbsp;Daniel Edgington-Mitchell,&nbsp;Petrônio Nogueira","doi":"10.1007/s00162-025-00772-y","DOIUrl":"10.1007/s00162-025-00772-y","url":null,"abstract":"<div><p>This work presents a linear stability analysis of the waves involved in the screech resonance loop generated within a rectangular supersonic jet. Linear stability analysis of rectangular jets has often been performed using a planar-jet approximation, due to the significant reduction in complexity and computational cost. However, the impact of this simplification on the predictive power of the stability model has not been considered in detail thus far. In this work, the predictions of both a simplified planar model and a more representative two-dimensional model are compared for two waves of particular relevance to jet noise. These waves are the downstream-propagating Kelvin-Helmholtz (KH) instability, and the upstream-propagating guided-jet mode (GJM). Disparity in the predicted wavenumber for both waves is considered, as well as disparities in the KH growth rate, and the GJM band of existence. A parametric sweep through nozzle-pressure ratio is performed for rectangular jets with aspect ratios ranging from a square jet with <span>(textrm{AR}=1)</span> to an <span>(textrm{AR}=8)</span> rectangular jet. It is demonstrated that the KH wavenumber can be well approximated by a planar model for rectangular geometries with an aspect ratio as low as 2. The growth rate is more sensitive, but for <span>(textrm{AR} ge 4)</span> the differences between the two models are negligible. In contrast to the KH waves, the band of existence of the GJM, defined as the frequency range between the mode’s branch and saddle points, shows significant dependence on the modelling approach. For higher aspect ratios, the planar model can reasonably predict the saddle point of the GJM, but the predicted branch point of the GJM differs significantly from that predicted by the two-dimensional model. Performing the analysis about an experimentally derived mean-flow profile demonstrates that the predictions for the GJM are sensitive to small changes in the flow profile, with both branch and saddle points showing a strong dependence on the thickness of the shear layer. In all cases tested, the two-dimensional model predicts a much narrower band of frequencies over which the GJM is supported by the flow, as compared to the planar model. To verify the predictions made from the two models, screech frequency predictions are made using the modified weakest-link model and compared to experimental data. The planar model, though it overpredicts the band of existence of the GJM, still produces correct predictions of screech frequency. The two-dimensional model, when linearized about the experimental mean flow, also correctly predicts the screech tones, though performs no better than the planar model.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 1","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145772156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}