arXiv - PHYS - Fluid Dynamics最新文献_第6页

Characterizing Turbulence at a Forest Edge: Comparing Sub-filter Scale Turbulence Models in Simulations of Flow over a Canopy 描述森林边缘的湍流：在模拟树冠上的水流时比较亚过滤器尺度的湍流模型

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-09 DOI: arxiv-2409.06047

Dorianis M. Perez, Jesse M. Canfield, Rodman R. Linn, Kevin Speer

{"title":"Characterizing Turbulence at a Forest Edge: Comparing Sub-filter Scale Turbulence Models in Simulations of Flow over a Canopy","authors":"Dorianis M. Perez, Jesse M. Canfield, Rodman R. Linn, Kevin Speer","doi":"arxiv-2409.06047","DOIUrl":"https://doi.org/arxiv-2409.06047","url":null,"abstract":"In wildfires, atmospheric turbulence plays a major role in the transfer of\u0000turbulent kinetic energy. Understanding how turbulence feeds back into a\u0000dynamical system is important, down to the varying small scales of fuel\u0000structures (i.e. pine needles, grass). Large eddy simulations (LES) are a\u0000common way of numerically representing turbulence. The Smagorinsky model (1963)\u0000serves as one of the most studied sub-grid scale representations in LES. In\u0000this investigation, the Smagorinsky model was implemented in HIGRAD/FIRETEC,\u0000LANL's coupled fire-atmosphere model. The Smagorinsky turbulent kinetic energy\u0000(TKE) was compared to FIRETEC's 1.5-order TKE eddy-viscosity subgrid-scale\u0000model, known as the Linn turbulence model. This was done in simulations of flow\u0000over flat terrain with a homogeneous, cuboidal canopy in the center of the\u0000domain. Examinations of the modeled vertical TKE profile and turbulent\u0000statistics at the leading edge, and throughout the canopy, show that the\u0000Smagorinsky model provides comparable results to that of the original closure\u0000model posed in FIRETEC.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Interaction between corner and bulk flows during drainage in granular porous media 粒状多孔介质排水过程中角流和散流的相互作用

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-09 DOI: arxiv-2409.05574

Paula Reis, Gaute Linga, Marcel Moura, Per Arne Rikvold, Renaud Toussaint, Eirik Grude Flekkøy, Knut Jørgen Måløy

{"title":"Interaction between corner and bulk flows during drainage in granular porous media","authors":"Paula Reis, Gaute Linga, Marcel Moura, Per Arne Rikvold, Renaud Toussaint, Eirik Grude Flekkøy, Knut Jørgen Måløy","doi":"arxiv-2409.05574","DOIUrl":"https://doi.org/arxiv-2409.05574","url":null,"abstract":"Drainage in porous media can be broken down into two main mechanisms: a\u0000primary piston-like displacement of the interfaces through the bulk of pore\u0000bodies and throats, and a secondary slow flow through corners and films in the\u0000wake of the invasion front. In granular porous media, this secondary drainage\u0000mechanism unfolds in connected pathways of pendular structures, such as\u0000capillary bridges and liquid rings, formed between liquid clusters. To\u0000represent both mechanisms, we proposed a dynamic dual-network model for\u0000drainage, considering that a gas displaces a wetting liquid from quasi-2D\u0000granular porous media. For this model, dedicated analyses of the capillary\u0000bridge shapes and hydraulic conductivity were conducted so that the secondary\u0000drainage mechanism could be properly quantified at finite speeds. With the\u0000model, an investigation of the wetting-phase connectivity and flow during\u0000drainage was carried out, covering a broad range of flow conditions. Results\u0000indicate that the span of liquid-connected structures in the unsaturated\u0000region, as well as their ability to contribute to flow, varies significantly\u0000with Capillary and Bond numbers.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212730","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Rough surfaces in under-explored surface morphology space and their implications on roughness modelling 探索不足的表面形态空间中的粗糙表面及其对粗糙度建模的影响

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-09 DOI: arxiv-2409.06089

Shyam S. Nair, Vishal A. Wadhai, Robert F. Kunz, Xiang I. A. Yang

{"title":"Rough surfaces in under-explored surface morphology space and their implications on roughness modelling","authors":"Shyam S. Nair, Vishal A. Wadhai, Robert F. Kunz, Xiang I. A. Yang","doi":"arxiv-2409.06089","DOIUrl":"https://doi.org/arxiv-2409.06089","url":null,"abstract":"We report direct numerical simulation (DNS) results of the rough-wall\u0000channel, focusing on roughness with high $k_{rms}/k_a$ statistics but small to\u0000negative $Sk$ statistics, and we study the implications of this new dataset on\u0000rough-wall modelling. Here, $k_{rms}$ is the root-mean-square, $k_a$ is the\u0000first order moment of roughness height, and $Sk$ is the skewness. The effects\u0000of packing density, skewness and arrangement of roughness elements on mean\u0000streamwise velocity, equivalent roughness height ($z_0$) and Reynolds and\u0000dispersive stresses have been studied. We demonstrate that two-point\u0000correlation lengths of roughness height statistics play an important role in\u0000characterizing rough surfaces with identical moments of roughness height but\u0000different arrangements of roughness elements. Analysis of the present as well\u0000as historical data suggests that the task of rough-wall modelling is to\u0000identify geometric parameters that distinguish the rough surfaces within the\u0000calibration dataset. We demonstrate a novel feature selection procedure to\u0000determine these parameters. Further, since there is not a finite set of\u0000roughness statistics that distinguish between all rough surfaces, we argue that\u0000obtaining a universal rough-wall model for making equivalent sand-grain\u0000roughness ($k_s$) predictions would be challenging, and that each rough-wall\u0000model would have its applicable range. This motivates the development of\u0000group-based rough-wall models. The applicability of multi-variate polynomial\u0000regression and feedforward neural networks for building such group-based\u0000rough-wall models using the selected features has been shown.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"114 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Critical latitude in global quasi-geostrophic flow on a rotating sphere 旋转球体上全球准地转流的临界纬度

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-09 DOI: arxiv-2409.05432

Arnout Franken, Erwin Luesink, Sagy Ephrati, Bernard Geurts

{"title":"Critical latitude in global quasi-geostrophic flow on a rotating sphere","authors":"Arnout Franken, Erwin Luesink, Sagy Ephrati, Bernard Geurts","doi":"arxiv-2409.05432","DOIUrl":"https://doi.org/arxiv-2409.05432","url":null,"abstract":"In this paper, we study geostrophic turbulence without external forcing or\u0000dissipation, using a Casimir-preserving numerical method. The research examines\u0000the formation of large zonal jets, common in geophysical flows, especially in\u0000giant gas planets. These jets form due to the east-west stretching of vortices,\u0000influenced by the gradient of the Coriolis parameter, leading to a critical\u0000latitude beyond which jets do not form. Using a global quasi-geostrophic model with a fully latitude-dependent\u0000Coriolis parameter, we investigate this critical latitude, which is theorized\u0000to depend only on the product of the Rossby number and the Lamb parameter. By\u0000simulating random flow fields, the critical latitude was identified through\u0000zonally averaged zonal velocity profiles. Results align with geostrophic theory, especially near typical Rossby and\u0000Lamb parameter values for Earth's atmosphere. However, in the regime of weak\u0000rotation (high Rossby numbers) and strong stratification (high Lamb values), no\u0000clear critical latitude emerges; instead, zonal jet amplitude and width\u0000decrease gradually towards the poles. This research paves the way for further\u0000study of jet dynamics under a fully latitude-dependent Coriolis parameter.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Characterizing Turbulence at a Forest Edge: A Vorticity Budget Analysis around a Canopy 森林边缘的湍流特征：树冠周围的涡度预算分析

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-09 DOI: arxiv-2409.06044

Dorianis M. Perez, Jesse M. Canfield, Rodman R. Linn, Kevin Speer

{"title":"Characterizing Turbulence at a Forest Edge: A Vorticity Budget Analysis around a Canopy","authors":"Dorianis M. Perez, Jesse M. Canfield, Rodman R. Linn, Kevin Speer","doi":"arxiv-2409.06044","DOIUrl":"https://doi.org/arxiv-2409.06044","url":null,"abstract":"Vorticity is a key characteristic of flow patterns that determine wildland\u0000fire behavior, frontal evolution, and wind-canopy interaction. Investigating\u0000the role of vorticity in the flow fields around vegetation can help us better\u0000understand fire-atmosphere feedback and the influences of vegetation on this\u0000feedback. In modeling vorticity, ``perhaps the greatest knowledge gap exists in\u0000understanding which terms in the vorticity equation dominate [...] (and) when\u0000one or the other might dominate\" (Potter, 2012). In this study, we investigate\u0000the role of vorticity in boundary layer dynamics and canopy/forest edge effects\u0000using HIGRAD/FIRETEC, a three-dimensional, two-phase transport model that\u0000conserves mass, momentum, energy, and chemical species. A vorticity transport\u0000equation was derived and discretized. Simulations were performed over a\u0000cuboidal homogeneous canopy surrounded by surface vegetation. This derivation\u0000led to the discovery of a drag tilting and stretching term, which shows that\u0000gradients in the aerodynamic drag of the vegetation, tied to heterogeneities in\u0000surface area-to-volume ratio, play an important role in the generation of\u0000vorticity. Results from the vorticity budget analysis show that this term\u0000contributes significantly in the areas where these gradients are present,\u0000namely the edges of the canopy.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Air jet impact craters on granular surfaces: a universal scaling 粒状表面上的空气喷射撞击坑：一种通用的比例尺

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-08 DOI: arxiv-2409.04988

Prasad Sonar, Hiroaki Katsuragi

引用次数: 0

Reynolds stress decay modeling informed by anisotropically forced homogeneous turbulence 以各向异性强迫均质湍流为基础的雷诺应力衰减模型

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-08 DOI: arxiv-2409.05179

Ty Homan, Omkar B. Shende, Ali Mani

{"title":"Reynolds stress decay modeling informed by anisotropically forced homogeneous turbulence","authors":"Ty Homan, Omkar B. Shende, Ali Mani","doi":"arxiv-2409.05179","DOIUrl":"https://doi.org/arxiv-2409.05179","url":null,"abstract":"Models for solving the Reynolds-averaged Navier-Stokes equations are popular\u0000tools for predicting complex turbulent flows due to their computational\u0000affordability and ability to provide or estimate quantities of engineering\u0000interest. However, results depend on a proper treatment of unclosed terms,\u0000which require progress in the development and assessment of model forms. In\u0000this study, we consider the Reynolds stress transport equations as a framework\u0000for second-moment turbulence closure modeling. We specifically focus on the\u0000terms responsible for decay of the Reynolds stresses, which can be isolated and\u0000evaluated separately from other terms in a canonical setup of homogeneous\u0000turbulence. We show that by using anisotropic forcing of the momentum equation,\u0000we can access states of turbulence traditionally not probed in a\u0000triply-periodic domain. The resulting data span a wide range of anisotropic\u0000turbulent behavior in a more comprehensive manner than extant literature. We\u0000then consider a variety of model forms for which these data allow us to perform\u0000a robust selection of model coefficients and select an optimal model that\u0000extends to cubic terms when expressed in terms of the principal coordinate\u0000Reynolds stresses. Performance of the selected decay model is then examined\u0000relative to the simulation data and popular models from the literature,\u0000demonstrating the superior accuracy of the developed model and, in turn, the\u0000efficacy of this framework for model selection and tuning.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"273 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Lattice Boltzmann Model for Transonic Flows 跨音速流动的玻尔兹曼晶格模型

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-08 DOI: arxiv-2409.05114

M. Atif, N. H. Maruthi, P. K. Kolluru, C. Thantanapally, S. Ansumali

引用次数: 0

Inverse cascade in zonal flows 带状流中的反向级联

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-08 DOI: arxiv-2409.05127

Siddhant Mishra, Anikesh Pal

引用次数: 0

Particle resuspension from complex multilayer deposits by laminar flows: statistical analysis and modeling 层流对复杂多层沉积物中颗粒的再悬浮：统计分析与建模

arXiv - PHYS - Fluid Dynamics Pub Date : 2024-09-08 DOI: arxiv-2409.05094

Hao Liu, Mireille Bossy, Bernhard Vowinckel, Christophe Henry

{"title":"Particle resuspension from complex multilayer deposits by laminar flows: statistical analysis and modeling","authors":"Hao Liu, Mireille Bossy, Bernhard Vowinckel, Christophe Henry","doi":"arxiv-2409.05094","DOIUrl":"https://doi.org/arxiv-2409.05094","url":null,"abstract":"Particle resuspension refers to the physical process by which solid particles\u0000deposited on a surface are, first, detached and, then, entrained away by the\u0000action of a fluid flow. In this study, we explore the dynamics of large and\u0000heavy spherical particles forming a complex sediment bed which is exposed to a\u0000laminar shear flow. For that purpose, we rely on fine-scale simulations based\u0000on a fully-resolved flow field around individual particles whose motion is\u0000explicitly tracked. Using statistical tools, we characterize several features:\u0000(a) the overall bed dynamics (e.g. the average particle velocity as a function\u0000of the elevation), (b) the evolution of the top surface of the sediment bed\u0000(e.g. distribution of the surface elevation or of the surface slope) and (c)\u0000the dynamics of individual particles as they detach from or re-attach to the\u0000sediment bed (including the frequency of these events, and the velocity\u0000difference / surface angle for each event). These results show that particles\u0000detach more frequently around the peaks in the top surface of the sediment bed\u0000and that, once detached, they undergo short hops as particles quickly sediment\u0000towards the sediment bed. A simple model based on the surface characteristics\u0000(including its slope and elevation) is proposed to reproduce the detachment\u0000ratio.","PeriodicalId":501125,"journal":{"name":"arXiv - PHYS - Fluid Dynamics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142212725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0