Theoretical and Computational Fluid Dynamics最新文献

{"title":"A three-dimensional analytical model for multiple jets based on reichardt’s hypothesis and velocity deflection interface concept","authors":"Fengsheng Qi,&nbsp;Liangyu Zhang,&nbsp;Deqiang Li,&nbsp;Xudong Tang,&nbsp;Zhongqiu Liu,&nbsp;Sheraman C. P. Cheung,&nbsp;Baokuan Li","doi":"10.1007/s00162-026-00782-4","DOIUrl":"10.1007/s00162-026-00782-4","url":null,"abstract":"<div><p>Analytical models are among the most direct and efficient methods for predicting jet behavior in engineering and practical applications. Based on Reichardt’s hypothesis, the momentum transformation equation for a single free jet was derived. Using a superposition approach, the momentum distribution for multiple jets was determined, enabling the development of a three-dimensional analytical model for multiple parallel jets. The effectiveness of this superposition technique in predicting the mean streamwise velocity components of multiple jets was validated through a combination of experimental and numerical simulations. For non-parallel jets, interactions between jets result in deflections as they enter the flow field, introducing the concept of a“velocity deflection interface”. Due to experimental limitations, accurately determining the position of the velocity deflection interface is challenging, making numerical simulations the preferred approach. The Shear-Stress transport (SST) k-<span>(upomega )</span> turbulence model was employed, and jet angles between 1<span>(^circ )</span> and 20<span>(^circ )</span> , commonly used in industrial applications, were analyzed. By fitting data along the flow direction, the position of the velocity deflection interface was identified, and its relationship with the jet angle was established. In the upstream region of the velocity deflection interface, the relationship between the velocity deflection interface and the initial jet exit characteristics was quantified. In the downstream region, the parallel jet theory based on Reichardt’s hypothesis was extended to derive analytical equations for three-dimensional non-parallel jets. Finally, a comparison of jet analysis results with experimental data and computational fluid dynamics (CFD) simulations confirmed the validity of the analytical model. It provides theoretical support for predicting the behavior of multiple jets in engineering applications.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 3","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738409","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":"Two-phase stratified MHD flows in wide rectangular ducts: analytical and numerical solutions","authors":"Ilya Barmak,&nbsp;Subham Pal,&nbsp;Alexander Gelfgat,&nbsp;Neima Brauner","doi":"10.1007/s00162-026-00780-6","DOIUrl":"10.1007/s00162-026-00780-6","url":null,"abstract":"<div><p>This study explores the effects of a non-conductive gas layer flowing concurrently with a conductive liquid on the two-phase flow characteristics in wide horizontal ducts under a constant vertical magnetic field. To this end, analytical solutions for the velocity profile and induced magnetic field are presented for laminar gas-liquid stratified magnetohydrodynamic (MHD) flow between two infinite plates of various conductivities. The contributions of the Lorentz force and wall shear stresses to the pressure gradient are examined. To the best of our knowledge, it is shown for the first time that, unlike the single-phase Hartmann flow, the velocity profiles in two-phase flow differ significantly depending on whether the bottom wall is conducting or insulating. In the case of an insulating bottom wall, the gas lubrication effect and potential pumping power savings are significantly greater (up to 50%), regardless of the magnetic Reynolds number. This conclusion also holds for gas-liquid MHD flows in rectangular ducts with finite width-to-height aspect ratios. To assess the applicability of the Two-Plate (TP) model to wide ducts, numerical solutions of the two-dimensional problem are used to investigate the influence of side walls on the two-phase flow characteristics, considering various combinations of bottom and side wall conductivities. In all cases, the results for high aspect ratios converge to the analytical solution obtained from the TP model with the same bottom wall conductivity. However, the influence of insulating side walls remains significant even at large aspect ratios when the bottom wall is conducting. Unexpectedly, in such cases, the change in the induced magnetic field due to the presence of side walls has a dramatic effect on the velocity profile, leading to a reduced pressure gradient compared to that predicted by the TP model. The results of this work are of practical significance for design of gas-liquid MHD flow systems with wide ducts of large, but finite, aspect ratio.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 2","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-026-00780-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147561639","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":"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}