Theoretical and Computational Fluid Dynamics最新文献

Robustness and limitations of fractal-dimension estimation methods for complex fluid interfaces 复杂流体界面分形维数估计方法的鲁棒性和局限性

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-10-05 DOI: 10.1007/s00162-026-00800-5

Marco Herbert, Josef Hasslberger, Maximilian Bambauer, Nilanjan Chakraborty, Markus Klein

{"title":"Robustness and limitations of fractal-dimension estimation methods for complex fluid interfaces","authors":"Marco Herbert, Josef Hasslberger, Maximilian Bambauer, Nilanjan Chakraborty, Markus Klein","doi":"10.1007/s00162-026-00800-5","DOIUrl":"10.1007/s00162-026-00800-5","url":null,"abstract":"<div><p>Fractal geometry provides a useful framework for characterizing highly wrinkled interfaces arising in fluid-dynamical and combustion processes. In this work, the robustness of three methods for estimating the fractal dimension, <span>(D_f)</span>, of empirical fractals is assessed: a filtering-based approach, the correlation dimension, and a grid-based box-counting method. The methods are applied to two challenging three-dimensional DNS datasets, namely primary liquid-jet atomization with strong droplet formation and a flame interface subject to Richtmyer-Meshkov instability (RMI). While all three methods show excellent agreement for mathematically defined fractals and reasonable agreement for weakly wrinkled surfaces, they are pushed to their limits for the complex physical interfaces considered here. Differences arise from both numerical sensitivities and the distinct structural and textural features captured by the individual estimators, and may lead to values outside expected or even physical bounds. Although the inferred inner cut-off scales remain within plausible ranges, method-dependent differences persist. For jet atomization, the box-counting method deviates markedly from the other approaches, whereas for the RMI configuration the filtering-based method is the clear outlier. Overall, the results demonstrate that heterogeneous empirical interfaces do not possess a unique, method-independent fractal dimension. Among the investigated methods, the correlation-dimension approach proved to be the most robust and consistently yielded physically plausible estimates across the wide range of interface topologies considered.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 5","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00162-026-00800-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149132104","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}

引用次数: 0

Correction: Global instability onset in high-speed compression corner flows 修正：全局不稳定开始于高速压缩角流

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-09-30 DOI: 10.1007/s00162-026-00799-9

Anton Scholten, Pedro Paredes, Meelan Choudhari, Fei Li

引用次数: 0

A numerical study of mean corrected phase-averaging in geophysical flow equations 地球物理流动方程中平均校正相位平均的数值研究。

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-09-03 DOI: 10.1007/s00162-026-00797-x

Timothy C. Andrews, Beth A. Wingate

{"title":"A numerical study of mean corrected phase-averaging in geophysical flow equations","authors":"Timothy C. Andrews, Beth A. Wingate","doi":"10.1007/s00162-026-00797-x","DOIUrl":"10.1007/s00162-026-00797-x","url":null,"abstract":"<p>This paper introduces a new algorithm to improve the accuracy of numerical phase-averaging in the oscillatory, multiscale, differential equations that govern geophysical fluid flow. Phase-averaging is a timestepping method that averages a mapped modulation variable in which the equations no longer contain a highly oscillatory linear term. This allows phase-averaging to retain the main contribution of fast waves on the low frequencies without explicitly resolving the rapid oscillations, thus allowing larger timesteps for explicit timesteppers. Whilst the modulation variable mapping is also used in operator splitting methods, and is accurate for asymptotic regimes, the advantage of phase-averaging is that low-frequency oscillations are retained, allowing for accuracy in systems further from the asymptotic limit. However, this comes at the cost of introducing an averaging error when computing phase-averages using a smooth kernel. This paper proposes a method to offset some averaging error through a modified mapping that includes a mean correction term to capture an average measure of nonlinear oscillation. We show that the mean corrected algorithm reduces phase-averaging errors in the swinging spring system and the one-dimensional rotating shallow water equations, which are an important geophysical fluid system for weather and climate applications. We discuss potential new directions for the method based on the outcome of the numerical experiments.</p>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 5","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13541800/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148896282","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}

引用次数: 0

Rupture of thin film covering the liquid metal stirred by alternating magnetic field. Numerical simulation 在交变磁场的搅动下，覆盖在液态金属上的薄膜破裂。数值模拟

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-09-03 DOI: 10.1007/s00162-026-00795-z

I. L. Nikulin, V. A. Demin, S. A. Nukulina

{"title":"Rupture of thin film covering the liquid metal stirred by alternating magnetic field. Numerical simulation","authors":"I. L. Nikulin, V. A. Demin, S. A. Nukulina","doi":"10.1007/s00162-026-00795-z","DOIUrl":"10.1007/s00162-026-00795-z","url":null,"abstract":"<div><p>The present work deals with the technological process of induction melting of heat-resistant nickel alloys and, in particular, with the problem of formation and stability of oxide film on the surface of the melt. Our mathematical model describes the heat and mass transfer in the metal melt subjected to the influence of an alternating magnetic field, and the elastic stress states of the film on its surface. The governing equations of the problem are given and non-dimensional parameters are discussed. It is shown how the influence of the magnetic field strength on the flow of the metal melt changes at different frequencies. The states of the surface film are studied theoretically using numerical simulation. It is shown that the variation of the field strength at different frequencies leads to decaying oscillations in the velocity field. The causes of these oscillations are discussed in detail. The stress and destruction of thin the film by melt motion is considered. The mechanisms responsible for the primary destruction of the initial film and its fragments are revealed. The rupture of quasi-stable films at different frequencies is studied. It is shown that the result of the influence on the film state with the increase of the magnetic field strength depends on the field frequency. The frequency range was found in which the surface film is strong enough to prevent the intensification of the melt flow with the increase of the magnetic field strength. This effect provides the stability of the film.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 5","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148926715","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}

引用次数: 0

Flow through a settling mesh 流动通过沉降网

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-08-31 DOI: 10.1007/s00162-026-00798-w

Bruce R. Sutherland, Benjamin Reeves

{"title":"Flow through a settling mesh","authors":"Bruce R. Sutherland, Benjamin Reeves","doi":"10.1007/s00162-026-00798-w","DOIUrl":"10.1007/s00162-026-00798-w","url":null,"abstract":"<div><p>As a starting point to gain an understanding of settling porous objects with complex geometries, such as marine snow and biofouled microplastics, we study the settling of a thin porous mesh. Motivating the theoretical-numerical work presented here are laboratory experiments that show the meshes settle without tumbling and the settling speed is effectively independent of the mesh lateral extent. The numerical simulations model flow through the mesh using a time-relaxation method. This captures the qualitative features of the laboratory experiments and gives insight into the dynamics governing the steady state settling velocity. Specifically it shows that a steep pressure gradient develops across the thickness of the mesh equal in magnitude to the reduced gravity, which itself equals the difference of the fluid and mesh velocity divided by the relaxation time scale. In effect, fluid is sucked through the mesh which provides the balance between buoyancy forces and drag controlled primarily by the mesh thickness, not its lateral extent. This insight justifies a dimensional analysis approach which successfully collapses measurements of the steady state flow across the mesh and mesh settling speeds thus giving semi-empirical predictions for these speeds as they depend upon the reduced gravity, mesh thickness and relaxation time scale.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 5","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148928021","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}

引用次数: 0

Stability of Oldroyd-B viscoelastic film flow on a uniformly heated slippery inclined plane Oldroyd-B粘弹性膜在均匀加热光滑斜面上流动的稳定性

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-08-25 DOI: 10.1007/s00162-026-00796-y

Mohmad Ismail, Akshay S. Desai, Amlan K. Barua, Amar K. Gaonkar

{"title":"Stability of Oldroyd-B viscoelastic film flow on a uniformly heated slippery inclined plane","authors":"Mohmad Ismail, Akshay S. Desai, Amlan K. Barua, Amar K. Gaonkar","doi":"10.1007/s00162-026-00796-y","DOIUrl":"10.1007/s00162-026-00796-y","url":null,"abstract":"<div><p>This study investigates the stability of an Oldroyd-B viscoelastic thin liquid film flowing over a uniformly heated slippery incline. Wall slip at the solid–liquid interface is modeled using a shear-slip boundary condition in which the boundary velocity is proportional to the tangential stress of the viscoelastic fluid. Using the weighted residual method (WRM), we derive coupled evolution equations for the film thickness and flow rate to investigate the combined influence of viscoelasticity, thermocapillary stresses, and slip on the stability of the liquid film. The predictive capability of the WRM is further compared against a long-wave Benney equation model (BEM). Linear stability analysis using normal-mode perturbations shows that, for small slip lengths <span>(beta sim O(epsilon ))</span>, where <span>(epsilon )</span> is the ratio of length scales in the cross-stream and stream-wise direction, the WRM-based critical Reynolds number captures the influence of slip, whereas the BEM prediction fails to do so. In contrast, for moderate slip <span>(beta sim O(1))</span>, both WRM and BEM successfully reflect the slip effect. For the parameter ranges considered, increasing the Deborah number, the Marangoni number, and the slip parameter enhances the growth rate of unstable disturbances, indicating that viscoelasticity, thermocapillary stresses, and slip all act as destabilizing influences within this long-wave regime. In addition, numerical simulations of the WRM in a periodic domain corroborate the predictions of linear stability analysis. These findings establish the enhanced predictive capability of the WRM for stability analysis in viscoelastic films with slip and heat.\u0000</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 5","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148837929","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}

引用次数: 0

Study of a system of turbulent shear layers and vortices. Part II: Reynolds-averaged turbulence modelling 紊流剪切层和涡旋系统的研究。第二部分：雷诺平均湍流模型

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-08-22 DOI: 10.1007/s00162-026-00789-x

Andrea Sansica, David J. Lusher, Li Wang, Gary N. Coleman, Philippe R. Spalart

{"title":"Study of a system of turbulent shear layers and vortices. Part II: Reynolds-averaged turbulence modelling","authors":"Andrea Sansica, David J. Lusher, Li Wang, Gary N. Coleman, Philippe R. Spalart","doi":"10.1007/s00162-026-00789-x","DOIUrl":"10.1007/s00162-026-00789-x","url":null,"abstract":"<div><p>This study investigates modelling a wavy turbulent shear layer that rolls up into two turbulent vortices, which then merge into one. The flow was designed for the shear layer to quickly become fully turbulent, and therefore to include a regime for which models developed for thin shear layers succeed as expected, followed by a much more challenging phase with curved shear layers and vortices. Part I of this study introduced the flow - which has unsteady two-dimensional Reynolds-averaged statistics - and its Direct Numerical Simulation (DNS), in particular presenting discussions of turbulence depletion during vortex formation and the possible emergence of opposite-signed vorticity. After showing the limits of basic Reynolds-Averaged Navier-Stokes (RANS) models, we here test two eddy-viscosity models with Rotation/Curvature (RC) corrections and a Reynolds-Stress Model (RSM), using peak vorticity and other measures for comparison. Independent RANS solvers and varying orders of numerical accuracy are assessed. Baseline Eddy-Viscosity Models (EVMs) fail to capture the turbulence depletion without RC corrections, which succeed by reducing eddy viscosity significantly. A Quadratic Constitutive Relation (QCR) is less impactful than RC terms. EVMs also generate spurious opposite vorticity at turbulent-inviscid interfaces; the origin of this is explored. The RSM outperforms baseline EVMs without added RC corrections, matching the best RC-adjusted results. To guide EVM improvement, we derive target eddy-viscosity fields from DNS and quantify shortcomings of the Boussinesq approximation. In other words, we address both the magnitude and the anisotropy of the Reynolds-stress tensor. We also compute the <span>(C_{cr1})</span> factor in QCR that aligns with DNS anisotropy across space and time, finding values generally below the standard 0.3. The paper concludes with analysis of the RC functions and insight for improving the correction terms.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 5","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148783361","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}

引用次数: 0

Computation of the Schwarz function and its application to vortex dynamics Schwarz函数的计算及其在涡旋动力学中的应用

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-08-12 DOI: 10.1007/s00162-026-00794-0

Samuel J. Harris, Cyan White, N. R. McDonald

引用次数: 0

Operator theoretic causality analysis of fluid flows using linearized dynamics 基于线性化动力学的流体流动算子因果分析

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-07-30 DOI: 10.1007/s00162-026-00793-1

Ankit Srivastava, Víctor Jiménez-Fernández, Louis N. Cattafesta III, Scott T. M. Dawson

{"title":"Operator theoretic causality analysis of fluid flows using linearized dynamics","authors":"Ankit Srivastava, Víctor Jiménez-Fernández, Louis N. Cattafesta III, Scott T. M. Dawson","doi":"10.1007/s00162-026-00793-1","DOIUrl":"10.1007/s00162-026-00793-1","url":null,"abstract":"<div><p>This paper presents an operator-theoretic framework, Linear Operator Causality Analysis (LOCA), for analyzing causality in linearized dynamical systems, focusing here on fluid flows. Our proposed approach, which can be characterized as a special case of Dynamic Causal Effect (DCE) analysis, utilizes the matrix exponential of linearized differential equations to determine causal relationships between system modes at any future time. We further develop an upper bound that quantifies the presence and extent of global causality across all time horizons. This approach provides a physics-based alternative to data-driven statistical and information-theoretic causality measures such as Granger causality and transfer entropy. Unlike these data-driven techniques that infer causality from time-series data, LOCA leverages the linearized governing equations, yielding a physically-motivated and interpretable measure of causal interactions. We identify the conditions under which LOCA gives equivalent results to data-driven causality analysis methods, and further discuss connections to key system properties such as controllability, observability, and graph-theoretic transitive closure. To complement this operator-based approach, we introduce a data-driven methodology akin to Dynamic Mode Decomposition (DMD) that estimates causal connections directly from time series data by approximating the matrix exponential. We argue that LOCA also mitigates common issues in data-driven causality analyses, such as misleading inferences due to correlated variables or state truncation. We demonstrate our method on two fluid flow examples: linearized Couette flow, and a nonlinear wake flow featuring chaotic dynamics. In both cases, we demonstrate how our framework captures both direct and indirect causal interactions among flow structures.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148615028","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}

引用次数: 0

Study of a system of turbulent shear layers and vortices. Part I: direct numerical simulation and theoretical considerations 紊流剪切层和涡旋系统的研究。第一部分：直接数值模拟和理论考虑

IF 3.4 3区工程技术

Theoretical and Computational Fluid Dynamics Pub Date : 2026-07-23 DOI: 10.1007/s00162-026-00788-y

David J. Lusher, Andrea Sansica, Gary N. Coleman, Philippe R. Spalart

{"title":"Study of a system of turbulent shear layers and vortices. Part I: direct numerical simulation and theoretical considerations","authors":"David J. Lusher, Andrea Sansica, Gary N. Coleman, Philippe R. Spalart","doi":"10.1007/s00162-026-00788-y","DOIUrl":"10.1007/s00162-026-00788-y","url":null,"abstract":"<div><p>A new vortex-dominated flow problem was defined to reveal some flow physics and to aid the design and assessment of turbulence models. The case is rich in turbulence and vorticity and physically complex although two-dimensional in the mean and free of solid boundaries. The <i>z</i> direction is homogeneous, and used for averages in the DNS so that the turbulence quantities are functions of (<i>x</i>, <i>y</i>, <i>t</i>). The flow is periodic in the <i>x</i> direction. The initial condition is a thin shear layer straddling the (<i>x</i>, <i>z</i>) plane and given a slight wave in the (<i>x</i>, <i>y</i>) plane. It is seeded with random perturbations, and turbulence develops before the Kelvin-Helmholtz instability creates two primary vortices. Each vortex entrains the shear layer into spiral sheets around itself, like vortices do over wings. Most RANS models are inaccurate in these situations, which is confirmed in the present case; they miss how the turbulence rapidly decays in and near the young vortex. The two vortices later collide and merge. The flow is driven by concurrent inviscid and turbulent phenomena, and RANS is more accurate for the former than the latter. A variety of measures of the numerical quality of the DNS are presented. We seek evidence that the vorticity exceeds the bounds of its initial condition. This cannot happen in (2D) laminar flow, but is common in RANS: vorticity of the sign opposite to the initial condition is generated by many models. We see strong evidence that this is not meaningfully present in the DNS, and attribute the small opposite excursions to the finite spatial-averaging interval and residual numerical errors. This matches our intuition, although we know of no theorem stating that opposite vorticity is unphysical. Part II contains comparisons with models, including eddy viscosity with and without rotation corrections and Reynolds-stress transport.</p></div>","PeriodicalId":795,"journal":{"name":"Theoretical and Computational Fluid Dynamics","volume":"40 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148613669","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}

引用次数: 0