Journal articles: 'Geophysical and environmental fluid flows'

1

Caulfield, C. P. "Layering, Instabilities, and Mixing in Turbulent Stratified Flows." Annual Review of Fluid Mechanics 53, no. 1 (January 5, 2021): 113–45. http://dx.doi.org/10.1146/annurev-fluid-042320-100458.

Full text

Abstract:

Understanding how turbulence leads to the enhanced irreversible transport of heat and other scalars such as salt and pollutants in density-stratified fluids is a fundamental and central problem in geophysical and environmental fluid dynamics. This review discusses recent research activity directed at improving community understanding, modeling, and parameterization of the subtle interplay between energy conversion pathways, instabilities, turbulence, external forcing, and irreversible mixing in density-stratified fluids. The conceptual significance of various length scales is highlighted, and in particular, the importance is stressed of overturning or scouring in the formation and maintenance of layered stratifications, i.e., robust density distributions with relatively deep and well-mixed regions separated by relatively thin interfaces of substantially enhanced density gradient.

APA, Harvard, Vancouver, ISO, and other styles

2

Deleersnijder, Eric, Fabien Cornaton, Thomas W. N. Haine, Marnik Vanclooster, and Darryn W. Waugh. "Tracer and timescale methods for understanding complex geophysical and environmental fluid flows." Environmental Fluid Mechanics 10, no. 1-2 (January 7, 2010): 1–5. http://dx.doi.org/10.1007/s10652-009-9164-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Hughes, Graham O. "Inside the head and tail of a turbulent gravity current." Journal of Fluid Mechanics 790 (February 1, 2016): 1–4. http://dx.doi.org/10.1017/jfm.2015.704.

Full text

Abstract:

Gravity currents are an important buoyancy-driven flow in environmental, geophysical and industrial settings. Turbulence and mixing is commonplace in these flows, but is typically overlooked in theoretical models and predictions. Sher & Woods (J. Fluid Mech., vol. 784, 2015, pp. 130–162) have quantified the velocity and density structure in turbulent gravity currents by combining high-quality experimental data with new theory. Their insights are set to stimulate significant advances in the area.

APA, Harvard, Vancouver, ISO, and other styles

4

Mallory, K., M. A. Hsieh, E. Forgoston, and I. B. Schwartz. "Distributed allocation of mobile sensing swarms in gyre flows." Nonlinear Processes in Geophysics 20, no. 5 (September 16, 2013): 657–68. http://dx.doi.org/10.5194/npg-20-657-2013.

Full text

Abstract:

Abstract. We address the synthesis of distributed control policies to enable a swarm of homogeneous mobile sensors to maintain a desired spatial distribution in a geophysical flow environment, or workspace. In this article, we assume the mobile sensors (or robots) have a "map" of the environment denoting the locations of the Lagrangian coherent structures or LCS boundaries. Using this information, we design agent-level hybrid control policies that leverage the surrounding fluid dynamics and inherent environmental noise to enable the team to maintain a desired distribution in the workspace. We discuss the stability properties of the ensemble dynamics of the distributed control policies. Since realistic quasi-geostrophic ocean models predict double-gyre flow solutions, we use a wind-driven multi-gyre flow model to verify the feasibility of the proposed distributed control strategy and compare the proposed control strategy with a baseline deterministic allocation strategy. Lastly, we validate the control strategy using actual flow data obtained by our coherent structure experimental testbed.

APA, Harvard, Vancouver, ISO, and other styles

5

Momen, Mostafa, Zhong Zheng, Elie Bou-Zeid, and Howard A. Stone. "Inertial gravity currents produced by fluid drainage from an edge." Journal of Fluid Mechanics 827 (August 29, 2017): 640–63. http://dx.doi.org/10.1017/jfm.2017.480.

Full text

Abstract:

We present theoretical, numerical and experimental studies of the release of a finite volume of fluid instantaneously from an edge of a rectangular domain for high Reynolds number flows. For the cases we considered, the results indicate that approximately half of the initial volume exits during an early adjustment period. Then, the inertial gravity current reaches a self-similar phase during which approximately 40 % of its volume drains and its height decreases as $\unicode[STIX]{x1D70F}^{-2}$, where $\unicode[STIX]{x1D70F}$ is a dimensionless time that is derived with the typical gravity wave speed and the horizontal length of the domain. Based on scaling arguments, we reduce the shallow-water partial differential equations into two nonlinear ordinary differential equations (representing the continuity and momentum equations), which are solved analytically by imposing a zero velocity boundary condition at the closed end wall and a critical Froude number condition at the open edge. The solutions are in good agreement with the performed experiments and direct numerical simulations for various geometries, densities and viscosities. This study provides new insights into the dynamical behaviour of a fluid draining from an edge in the inertial regime. The solutions may be useful for environmental, geophysical and engineering applications such as open channel flows, ventilations and dam-break problems.

APA, Harvard, Vancouver, ISO, and other styles

6

LIU, M. B., G. R. LIU, and Z. ZONG. "AN OVERVIEW ON SMOOTHED PARTICLE HYDRODYNAMICS." International Journal of Computational Methods 05, no. 01 (March 2008): 135–88. http://dx.doi.org/10.1142/s021987620800142x.

Full text

Abstract:

This paper presents an overview on smoothed particle hydrodynamics (SPH), which is a meshfree, particle method of Lagrangian nature. In theory, the interpolation and approximations of the SPH method and the corresponding numerical errors are analyzed. The inherent particle inconsistency has been discussed in detail. It has been demonstrated that the particle inconsistency originates from the discrete particle approximation process and is the fundamental cause for poor approximation accuracy. Some particle consistency restoring approaches have been reviewed. In application, SPH modeling of general fluid dynamics and hyperdynamics with material strength have been reviewed with emphases on (1) microfluidics and microdrop dynamics, (2) coast hydrodynamics and offshore engineering, (3) environmental and geophysical flows, (4) high-explosive detonation and explosions, (5) underwater explosions, and (6) hydrodynamics with material strength including hypervelocity impact and penetration.

APA, Harvard, Vancouver, ISO, and other styles

7

Grobbe, N., and S. Barde-Cabusson. "Self-Potential Studies in Volcanic Environments: A Cheap and Efficient Method for Multiscale Fluid-Flow Investigations." International Journal of Geophysics 2019 (October 20, 2019): 1–19. http://dx.doi.org/10.1155/2019/2985824.

Full text

Abstract:

We demonstrate the value of using the self-potential method to study volcanic environments, and particularly fluid flow in those environments. We showcase the fact that self-potential measurements are a highly efficient way to map large areas of volcanic systems under challenging terrain conditions, where other geophysical techniques may be challenging or expensive to deploy. Using case studies of a variety of volcano types, including tuff cones, shield volcanoes, stratovolcanoes, and monogenetic fields, we emphasize the fact that self-potential signals enable us to study fluid flow in volcanic settings on multiple spatial and temporal scales. We categorize the examples into the following three multiscale fluid-flow processes: (1) deep hydrothermal systems, (2) shallow hydrothermal systems, and (3) groundwater. These examples highlight the different hydrological, hydrothermal, and structural inferences that can be made from self-potential signals, such as insight into shallow and deep hydrothermal systems, cooling behavior of lava flows, different hydrogeological domains, upwelling, infiltration, and lateral groundwater and hydrothermal fluid flow paths and velocities, elevation of the groundwater level, crater limits, regional faults, rift zones, incipient collapse limits, structural domains, and buried calderas. The case studies presented in this paper clearly demonstrate that the measured SP signals are a result of the coplay between microscale processes (e.g., electrokinetic, thermoelectric) and macroscale structural and environmental features. We discuss potential challenges and their causes when trying to uniquely interpret self-potential signals. Through integration with different geophysical and geochemical data types such as subsurface electrical resistivity distributions obtained from, e.g., electrical resistivity tomography or magnetotellurics, soil CO2 flux, and soil temperature, it is demonstrated that the hydrogeological interpretations obtained from SP measurements can be better constrained and/or validated.

APA, Harvard, Vancouver, ISO, and other styles

8

Eggenhuisen, Joris T., Matthieu J. B. Cartigny, and Jan de Leeuw. "Physical theory for near-bed turbulent particle suspension capacity." Earth Surface Dynamics 5, no. 2 (May 17, 2017): 269–81. http://dx.doi.org/10.5194/esurf-5-269-2017.

Full text

Abstract:

Abstract. The inability to capture the physics of solid-particle suspension in turbulent fluids in simple formulas is holding back the application of multiphase fluid dynamics techniques to many practical problems in nature and society involving particle suspension. We present a force balance approach to particle suspension in the region near no-slip frictional boundaries of turbulent flows. The force balance parameter Γ contains gravity and buoyancy acting on the sediment and vertical turbulent fluid forces; it includes universal turbulent flow scales and material properties of the fluid and particles only. Comparison to measurements shows that Γ = 1 gives the upper limit of observed suspended particle concentrations in a broad range of flume experiments and field settings. The condition of Γ > 1 coincides with the complete suppression of coherent turbulent structures near the boundary in direct numerical simulations of sediment-laden turbulent flow. Γ thus captures the maximum amount of sediment that can be contained in suspension at the base of turbulent flow, and it can be regarded as a suspension capacity parameter. It can be applied as a simple concentration boundary condition in modelling studies of the dispersion of particulates in environmental and man-made flows.

APA, Harvard, Vancouver, ISO, and other styles

9

Devi, Kalpana, Prashanth Reddy Hanmaiahgari, Ram Balachandar, and Jaan H. Pu. "A Comparative Study between Sand- and Gravel-Bed Open Channel Flows in the Wake Region of a Bed-Mounted Horizontal Cylinder." Fluids 6, no. 7 (July 1, 2021): 239. http://dx.doi.org/10.3390/fluids6070239.

Full text

Abstract:

In nature, environmental and geophysical flows frequently encounter submerged cylindrical bodies on a rough bed. The flows around the cylindrical bodies on the rough bed are very complicated as the flow field in these cases will be a function of bed roughness apart from the diameter of the cylinder and the flow velocity. In addition, the sand-bed roughness has different effects on the flow compared to the gravel-bed roughness due to differences in the roughness heights. Therefore, the main objective of this article is to compare the mean velocities and turbulent flow properties in the wake region of a horizontal bed-mounted cylinder over the sand-bed with that over the gravel-bed. Three experimental runs, two for the sand-bed and one for the gravel-bed with similar physical and hydraulic conditions, were recorded to fulfil this purpose. The Acoustic Doppler Velocimetry (ADV) probe was used for measuring the three-dimensional (3D) instantaneous velocity data. This comparative study shows that the magnitude of mean streamwise flow velocity, streamwise Reynolds normal stress, and Reynolds shear stress are reduced on the gravel-bed compared to the sand-bed. Conversely, the vertical velocities and vertical Reynolds normal stress are higher on the gravel-bed than the sand-bed.

APA, Harvard, Vancouver, ISO, and other styles

10

Matulka, A., P. López, J. M. Redondo, and A. Tarquis. "On the entrainment coefficient in a forced plume: quantitative effects of source parameters." Nonlinear Processes in Geophysics 21, no. 1 (February 24, 2014): 269–78. http://dx.doi.org/10.5194/npg-21-269-2014.

Full text

Abstract:

Abstract. The behavior of a forced plume is mainly controlled by the source buoyancy and momentum fluxes and the efficiency of turbulent mixing between the plume and the ambient fluid (stratified or not). The interaction between the plume and the ambient fluid controls the plume dynamics and is usually represented by the entrainment coefficient αE. Commonly used one-dimensional models incorporating a constant entrainment coefficient are fundamental and very useful for predictions in geophysical flows and industrial situations. Nevertheless, if the basic geometry of the flow changes, or the type of source or the environmental fluid conditions (e.g., level of turbulence, shear, ambient stratification, presence of internal waves), new models allowing for variable entrainment are necessary. The presented paper is an experimental study based on a set of turbulent plume experiments in a calm unstratified ambient fluid under different source conditions (represented by different buoyancy and momentum fluxes). The main result is that the entrainment coefficient is not a constant and clearly varies in time within the same plume independently of the buoyancy and the source position. This paper also analyzes the influence of the source conditions on the mentioned time evolution. The measured entrainment coefficient αE has considerable variability. It ranges between 0.26 and 0.9 for variable Atwood number experiments and between 0.16 and 0.55 for variable source position experiments. As is observed, values are greater than the traditional standard value of Morton et al. (1956) for plumes and jets, which is about 0.13.

APA, Harvard, Vancouver, ISO, and other styles

11

Río-Martín, Laura, Saray Busto, and Michael Dumbser. "A Massively Parallel Hybrid Finite Volume/Finite Element Scheme for Computational Fluid Dynamics." Mathematics 9, no. 18 (September 18, 2021): 2316. http://dx.doi.org/10.3390/math9182316.

Full text

Abstract:

In this paper, we propose a novel family of semi-implicit hybrid finite volume/finite element schemes for computational fluid dynamics (CFD), in particular for the approximate solution of the incompressible and compressible Navier-Stokes equations, as well as for the shallow water equations on staggered unstructured meshes in two and three space dimensions. The key features of the method are the use of an edge-based/face-based staggered dual mesh for the discretization of the nonlinear convective terms at the aid of explicit high resolution Godunov-type finite volume schemes, while pressure terms are discretized implicitly using classical continuous Lagrange finite elements on the primal simplex mesh. The resulting pressure system is symmetric positive definite and can thus be very efficiently solved at the aid of classical Krylov subspace methods, such as a matrix-free conjugate gradient method. For the compressible Navier-Stokes equations, the schemes are by construction asymptotic preserving in the low Mach number limit of the equations, hence a consistent hybrid FV/FE method for the incompressible equations is retrieved. All parts of the algorithm can be efficiently parallelized, i.e., the explicit finite volume step as well as the matrix-vector product in the implicit pressure solver. Concerning parallel implementation, we employ the Message-Passing Interface (MPI) standard in combination with spatial domain decomposition based on the free software package METIS. To show the versatility of the proposed schemes, we present a wide range of applications, starting from environmental and geophysical flows, such as dambreak problems and natural convection, over direct numerical simulations of turbulent incompressible flows to high Mach number compressible flows with shock waves. An excellent agreement with exact analytical, numerical or experimental reference solutions is achieved in all cases. Most of the simulations are run with millions of degrees of freedom on thousands of CPU cores. We show strong scaling results for the hybrid FV/FE scheme applied to the 3D incompressible Navier-Stokes equations, using millions of degrees of freedom and up to 4096 CPU cores. The largest simulation shown in this paper is the well-known 3D Taylor-Green vortex benchmark run on 671 million tetrahedral elements on 32,768 CPU cores, showing clearly the suitability of the presented algorithm for the solution of large CFD problems on modern massively parallel distributed memory supercomputers.

APA, Harvard, Vancouver, ISO, and other styles

12

Chen, Hung-Cheng, Jai-Houng Leu, Yong Liu, He-Sheng Xie, and Qiang Chen. "A Validated Study of a Modified Shallow Water Model for Strong Cyclonic Motions and Their Structures in a Rotating Tank." Mathematical Problems in Engineering 2021 (April 30, 2021): 1–15. http://dx.doi.org/10.1155/2021/5529601.

Full text

Abstract:

A joint theoretical and numerical study was carried out to investigate the fluid dynamical aspect of the motion of a vortex generated in a rotating tank with a sloping bottom. This study aims at understanding the evolution of strong cyclonic motions on a β-plane in the Northern Hemisphere. The strong cyclonic vortices were characterized by four nondimensional parameters which were derived through a scale analysis of the depth variations of fluid. By simplifying the model flow field and the prototype flow field, respectively, through the conservation of potential vorticity, two sets of dynamic similarity conditions are derived. This study proposed a sophisticated modified shallow water model (MSWM) to investigate the flow features of such strong vortices. A detailed numerical calculation adopted by multidimensional positive definite advection transport algorithm (MPDATA) was carried out to validate those effects considered in the MSWM model, including sloping bottom, parabolic free surface deformation, and viscous dissipation. Close agreements were found between the experimental and numerical results, including the streamlines patterns and the vortex trajectory. Comprehensive simulations for strong cyclonic vortices over different sloping bottoms were investigated to understand the impact of planetary β effect on vortex. The results calculated by MSWM demonstrate a variety of flow features of interactions between the primary vortex and induced secondary Rossby wave wakes that were essential and prominent in environmental geophysical flows.

APA, Harvard, Vancouver, ISO, and other styles

13

Salehipour, Hesam, W. R. Peltier, and C. P. Caulfield. "Self-organized criticality of turbulence in strongly stratified mixing layers." Journal of Fluid Mechanics 856 (October 2, 2018): 228–56. http://dx.doi.org/10.1017/jfm.2018.695.

Full text

Abstract:

Motivated by the importance of stratified shear flows in geophysical and environmental circumstances, we characterize their energetics, mixing and spectral behaviour through a series of direct numerical simulations of turbulence generated by Holmboe wave instability (HWI) under various initial conditions. We focus on circumstances where the stratification is sufficiently ‘strong’ so that HWI is the dominant primary instability of the flow. Our numerical findings demonstrate the emergence of self-organized criticality (SOC) that is manifest as an adjustment of an appropriately defined gradient Richardson number, $Ri_{g}$, associated with the horizontally averaged mean flow, in such a way that it is continuously attracted towards a critical value of $Ri_{g}\sim 1/4$. This self-organization occurs through a continuously reinforced localization of the ‘scouring’ motions (i.e. ‘avalanches’) that are characteristic of the turbulence induced by the breakdown of Holmboe wave instabilities and are developed on the upper and lower flanks of the sharply localized density interface, embedded within a much more diffuse shear layer. These localized ‘avalanches’ are also found to exhibit the expected scale-invariant characteristics. From an energetics perspective, the emergence of SOC is expressed in the form of a long-lived turbulent flow that remains in a ‘quasi-equilibrium’ state for an extended period of time. Most importantly, the irreversible mixing that results from such self-organized behaviour appears to be characterized generically by a universal cumulative turbulent flux coefficient of $\unicode[STIX]{x1D6E4}_{c}\sim 0.2$ only for turbulent flows engendered by Holmboe wave instability. The existence of this self-organized critical state corroborates the original physical arguments associated with self-regulation of stratified turbulent flows as involving a ‘kind of equilibrium’ as described by Turner (1973, Buoyancy Effects in Fluids, Cambridge University Press).

APA, Harvard, Vancouver, ISO, and other styles

14

Kehoe, Ryan M., Mark A. Boothe, and Russell L. Elsberry. "Dynamical Tropical Cyclone 96- and 120-h Track Forecast Errors in the Western North Pacific." Weather and Forecasting 22, no. 3 (June 1, 2007): 520–38. http://dx.doi.org/10.1175/waf1002.1.

Full text

Abstract:

Abstract The Joint Typhoon Warning Center has been issuing 96- and 120-h track forecasts since May 2003. It uses four dynamical models that provide guidance at these forecast intervals and relies heavily on a consensus of these four models in producing the official forecast. Whereas each of the models has skill, each occasionally has large errors. The objective of this study is to provide a characterization of these errors in the western North Pacific during 2004 for two of the four models: the Navy Operational Global Atmospheric Prediction System (NOGAPS) and the U.S. Navy’s version of the Geophysical Fluid Dynamics Laboratory model (GFDN). All 96- and 120-h track errors greater than 400 and 500 n mi, respectively, are examined following the approach developed recently by Carr and Elsberry. All of these large-error cases can be attributed to the models not properly representing the physical processes known to control tropical cyclone motion, which were classified in a series of conceptual models by Carr and Elsberry for either tropical-related or midlatitude-related mechanisms. For those large-error cases where an error mechanism could be established, midlatitude influences caused 83% (85%) of the NOGAPS (GFDN) errors. The most common tropical influence is an excessive direct cyclone interaction in which the tropical cyclone track is erroneously affected by an adjacent cyclone. The most common midlatitude-related errors in the NOGAPS tracks arise from an erroneous prediction of the environmental flow dominated by a ridge in the midlatitudes. Errors in the GFDN tracks are caused by both ridge-dominated and trough-dominated environmental flows in the midlatitudes. Case studies illustrating the key error mechanisms are provided. An ability to confidently identify these error mechanisms and thereby eliminate likely erroneous tracks from the consensus would improve the accuracy of 96- and 120-h track forecasts.

APA, Harvard, Vancouver, ISO, and other styles

15

Marques, Tiago, Manuel Senos Matias, Eduardo Ferreira da Silva, Nuno Durães, and Carla Patinha. "Temporal and Spatial Groundwater Contamination Assessment Using Geophysical and Hydrochemical Methods: The Industrial Chemical Complex of Estarreja (Portugal) Case Study." Applied Sciences 11, no. 15 (July 22, 2021): 6732. http://dx.doi.org/10.3390/app11156732.

Full text

Abstract:

With more than a half-century in operation, the industrial chemical complex of Estarreja (ICCE) in northern Portugal has left serious environmental liabilities in the region. Although protective measures were implemented, soils, surface, and groundwater contamination caused by persistent pollutants are still prevalent. This study presents data from several geophysical and hydrochemical campaigns carried out to monitor groundwater contamination in the Estarreja region over a period of 30 years. Both geophysical and hydrochemical data showed a good agreement and revealed an important anomaly caused by groundwater contamination (high levels of Na, Cl, SO4, and Fe, among others) in 2006–2007, likely caused by the remobilization of waste pollutants (roasted pyrites, soils, and sludge) during their deposition in a sealed landfill (operating between 2003 and 2005). More recently, in 2016, this impact persists, but was more attenuated and showed a general migration pattern from E to SW according to one of the main groundwater flow paths. Groundwater flow in this region has a local radial behaviour. Drainage effluent systems, such as ditches and buried pipes formerly used by ICCE, are also likely to contribute to some contamination “hotspots”. Finally, the results obtained by the combined use of these two approaches allowed for the delineation of the contamination plume for future monitoring.

APA, Harvard, Vancouver, ISO, and other styles

16

Melkov, Dmitry, Vladislav Zaalishvili, Olga Burdzieva, and Aleksandr Kanukov. "Temporal and Spatial Geophysical Data Analysis in the Issues of Natural Hazards and Risk Assessment (in Example of North Ossetia, Russia)." Applied Sciences 12, no. 6 (March 9, 2022): 2790. http://dx.doi.org/10.3390/app12062790.

Full text

Abstract:

The paper considers the aspects of hazard assessment within the framework of a generalized approach. The aim of the study is to improve the methodology for more accurate and detailed probabilistic assessments of risks of various nature. A complex hazard map is constructed in an example of the territory of the Republic of North Ossetia-Alania and the construction site of the Mamison resort. Based on the analysis of data on Quaternary formations and quantitative estimates, it was concluded that the natural average static environmental evolution proceeds in the mode of the dynamic balance of two factors: mountain building and the equivalent increase in denudation, of which about 90% is transported and deposited by river waters and winds outside the territory. The remaining 10% is deposited in intermountain depressions and river valleys in situ. Geodynamic and climatic factors of influence on the geoenvironment create the danger of excessive environmental impact and disruption of its equilibrium development under anthropogenic impacts, which must be taken into account in designing.

APA, Harvard, Vancouver, ISO, and other styles

17

Volynkin, Sergey S., Svetlana B. Bortnikova, Nataliya V. Yurkevich, Olga V. Shuvaeva, and Sofia P. Kohanova. "Determination of Arsenic Species Distribution in Arsenide Tailings and Leakage Using Geochemical and Geophysical Methods." Applied Sciences 13, no. 2 (January 12, 2023): 1067. http://dx.doi.org/10.3390/app13021067.

Full text

Abstract:

This study describes the distribution of arsenic mobile species in the tailings of Cu–Co–Ni–arsenide using the sequential extraction and determining the contents of arsenate (AsV) and arsenite (AsIII). The object of this study is the tailings ponds of the Tuvakobalt plant, which contains waste from the hydrometallurgical arsenide ore processing of the Khovu-Aksy deposit (Republic of Tuva, Russia). A procedure of sequential extraction for arsenic was applied, and it includes the extraction of the following forms: water-soluble, potentially water-soluble and exchangeable, easily sorbed on the surface of carbonates, associated with Fe/Mn oxides/hydroxides, associated with easily oxidized minerals, and accounted for by non-oxidized arsenic minerals. This procedure, which takes into account the peculiarities of the physical and chemical composition of the waste, was supplemented by the analytical determination of the arsenite and arsenate content by using the methods of inductively coupled plasma atomic emission spectrometry (ICP-AES) combined with the hydride generation technique (HG-ICP-AES). The content of the most mobile forms of arsenic, which are water-soluble, potentially water-soluble, and exchangeable species, is equal to 56% of the total arsenic content, 23% and 33% of which are arsenite and arsenate, respectively. Unlike arsenic, the mobile forms of metals have been determined in small quantities. The largest proportion of water-soluble and exchangeable forms is formed by Mg, Ca, and Sr at 11, 9.4, and 20%, respectively (residual and redeposited carbonates). The proportion of water-soluble forms of other metals (Cu, Zn, Co, and Ni) is < 1% or 0. The main part of the metals is adsorbed on the surface of Fe and Mn hydroxides, enclosed in easily and hardly oxidized minerals. In addition to geochemical studies, the presence of leaks from the tailing ponds into ground waters was determined by using electrical resistivity tomography. The data obtained indicate a high environmental hazard of tailings and the possibility of water-soluble and highly toxic arsenic compounds entering ground waters and aquifers.

APA, Harvard, Vancouver, ISO, and other styles

18

Nardecchia, Fabio, Annalisa Di Bernardino, Francesca Pagliaro, Paolo Monti, Giovanni Leuzzi, and Luca Gugliermetti. "CFD Analysis of Urban Canopy Flows Employing the V2F Model: Impact of Different Aspect Ratios and Relative Heights." Advances in Meteorology 2018 (July 29, 2018): 1–16. http://dx.doi.org/10.1155/2018/2189234.

Full text

Abstract:

Computational fluid dynamics (CFD) is currently used in the environmental field to simulate flow and dispersion of pollutants around buildings. However, the closure assumptions of the turbulence usually employed in CFD codes are not always physically based and adequate for all the flow regimes relating to practical applications. The starting point of this work is the performance assessment of the V2F (i.e., v2¯ − f) model implemented in Ansys Fluent for simulating the flow field in an idealized array of two-dimensional canyons. The V2F model has been used in the past to predict low-speed and wall-bounded flows, but it has never been used to simulate airflows in urban street canyons. The numerical results are validated against experimental data collected in the water channel and compared with other turbulence models incorporated in Ansys Fluent (i.e., variations of both k-ε and k-ω models and the Reynolds stress model). The results show that the V2F model provides the best prediction of the flow field for two flow regimes commonly found in urban canopies. The V2F model is also employed to quantify the air-exchange rate (ACH) for a series of two-dimensional building arrangements, such as step-up and step-down configurations, having different aspect ratios and relative heights of the buildings. The results show a clear dependence of the ACH on the latter two parameters and highlight the role played by the turbulence in the exchange of air mass, particularly important for the step-down configurations, when the ventilation associated with the mean flow is generally poor.

APA, Harvard, Vancouver, ISO, and other styles

19

Zaalishvili, Vladislav, Olga Burdzieva, Aleksandr Kanukov, and Tamaz Zaks. "Eco-Geophysical and Geoecological Factors in Assessing the State of the Geological Environment Based on the Analysis of Spatial Databases of the Territory of the Republic of North Ossetia–Alania." Applied Sciences 12, no. 5 (March 3, 2022): 2644. http://dx.doi.org/10.3390/app12052644.

Full text

Abstract:

The article considers the main sources of pollutionin the territory of the Republic of North Ossetia–Alania. A study of environmental geophysical factors in the city of Vladikavkaz was carried out at 126 points; indicators of noise pollution, electric fields and the level of gamma radiation were measured. A geoaccumulation index of heavy metals in soils and indices of carcinogenic and non-carcinogenic risks were calculated and corresponding maps were constructed. The obtained data supporting a high level of carcinogenic risk are consistent with a high level of cancer morbidity in the city, which indicates a close relationship between morbidity and the carcinogenic risk index. It has been determined that emissions from road transport are greater by an order of magnitude than stationary sources emissions, while there is a steady trend towards an increase in air pollution as a result of the increasing negative impact of motor vehicle emissions. It has been established that the most hazardous way for heavy metals to enter the human body from the soil is by inhalation. It has been determined that in areas where environmental pollution with heavy metals is higher, cancer morbidity is also higher.

APA, Harvard, Vancouver, ISO, and other styles

20

CHUESHOV, IGOR, JINQIAO DUAN, and BJÖRN SCHMALFUSS. "PROBABILISTIC DYNAMICS OF TWO-LAYER GEOPHYSICAL FLOWS." Stochastics and Dynamics 01, no. 04 (December 2001): 451–75. http://dx.doi.org/10.1142/s0219493701000229.

Full text

Abstract:

The two-layer quasigeostrophic flow model is an intermediate system between the single-layer two-dimensional barotropic flow model and the continuously stratified three-dimensional baroclinic flow model. This model is widely used to investigate basic mechanisms in geophysical flows, such as baroclinic effects, the Gulf stream and subtropical gyres. We consider the two-layer quasigeostrophic flow model under stochastic wind forcing on the top layer. The fluctuating part of the wind forcing is modeled as the generalized time derivative of a Wiener process. We first transform this stochastic two-layer fluid system into a coupled system of random partial differential equations. Then we prove that the stochastic two-layer fluid system has finite sets of asymptotically determining functionals (such as determining modes and determining nodes) in probability. Furthermore, we show that the asymptotic probabilistic dynamics of this system depends only on the top fluid layer. Namely, in the probability sense and asymptotically, the dynamics of the two-layer quasigeostrophic fluid system is determined by the top layer. In other words, the bottom layer is slaved by the top layer. This conclusion is true provided that the Wiener process and the fluid parameters satisfy a certain condition. In particular, this latter condition is satisfied when the trace of the covariance operator of the Wiener process is small enough and the Ekman constant r is sufficiently large.

APA, Harvard, Vancouver, ISO, and other styles

21

Bannister, R. N., D. Katz, M. J. P. Cullen, A. S. Lawless, and N. K. Nichols. "Modelling of forecast errors in geophysical fluid flows." International Journal for Numerical Methods in Fluids 56, no. 8 (2008): 1147–53. http://dx.doi.org/10.1002/fld.1618.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Chashechkin, Y. D. "Atomic-molecular effects in geophysical hydrodynamics." IOP Conference Series: Earth and Environmental Science 1040, no. 1 (June 1, 2022): 012028. http://dx.doi.org/10.1088/1755-1315/1040/1/012028.

Full text

Abstract:

Abstract To calculate the dynamics and structure of flows, a system of fundamental equations of fluid mechanics with equations of state for the Gibbs potential and density of an inhomogeneous medium is applied. The complete solution of the system describes ligaments, waves, vortices, jets, wakes, and other types of flows. Calculations of flow patterns around obstacles are consistent with the experiment. Observations of the processes of merging a freely falling drop with a target fluid revealed that the finest components are formed during the direct generation of ligaments by atomic-molecular processes. The involvement of a scaled and parametrically invariant system of fundamental equations permits the study of unsteady energetic flows and more accurately describes their dynamics and structure in the whole range of scales from microscopic to global.

APA, Harvard, Vancouver, ISO, and other styles

23

Bokhove, Onno, and Marcel Oliver. "Parcel Eulerian–Lagrangian fluid dynamics of rotating geophysical flows." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 462, no. 2073 (March 30, 2006): 2575–92. http://dx.doi.org/10.1098/rspa.2006.1656.

Full text

Abstract:

Parcel Eulerian–Lagrangian Hamiltonian formulations have recently been used in structure-preserving numerical schemes, asymptotic calculations and in alternative explanations of fluid parcel (in)stabilities. A parcel formulation describes the dynamics of one fluid parcel with a Lagrangian kinetic energy but an Eulerian potential evaluated at the parcel's position. In this paper, we derive the geometric link between the parcel Eulerian–Lagrangian formulation and well-known variational and Hamiltonian formulations for three models of ideal and geophysical fluid flow: generalized two-dimensional vorticity–stream function dynamics, the rotating two-dimensional shallow-water equations and the rotating three-dimensional compressible Euler equations.

APA, Harvard, Vancouver, ISO, and other styles

24

Zhang, Xinguang, Lishan Liu, Yonghong Wu, B. Wiwatanapataphee, and Yujun Cui. "Solvability and asymptotic properties for an elliptic geophysical fluid flows model in a planar exterior domain." Nonlinear Analysis: Modelling and Control 26, no. 2 (March 1, 2021): 315–33. http://dx.doi.org/10.15388/namc.2021.26.21202.

Full text

Abstract:

In this paper, we study the solvability and asymptotic properties of a recently derived gyre model of nonlinear elliptic Schrödinger equation arising from the geophysical fluid flows. The existence theorems and the asymptotic properties for radial positive solutions are established due to space theory and analytical techniques, some special cases and specific examples are also given to describe the applicability of model in gyres of geophysical fluid flows.

APA, Harvard, Vancouver, ISO, and other styles

25

San, Omer. "Recent Numerical Advances in Fluid Mechanics." Fluids 5, no. 2 (May 15, 2020): 73. http://dx.doi.org/10.3390/fluids5020073.

Full text

Abstract:

In recent decades, the field of computational fluid dynamics has made significant advances in enabling advanced computing architectures to understand many phenomena in biological, geophysical, and engineering fluid flows [...]

APA, Harvard, Vancouver, ISO, and other styles

26

Tian, Baofeng, Xiyang Li, Haoyu Duan, Liang Wang, Hui Zhu, and Hui Luan. "Harmonic Elimination and Magnetic Resonance Sounding Signal Extraction Based on Matching Pursuit Algorithm." Applied Sciences 13, no. 1 (December 28, 2022): 376. http://dx.doi.org/10.3390/app13010376.

Full text

Abstract:

Magnetic resonance sounding (MRS) is a non-invasive, direct, and quantitative geophysical method for detecting groundwater, and has been widely used in groundwater survey, water resource assessment, and disaster water source forecasting. However, the MRS signal is weak (nV level) and highly susceptible to environmental noise, such as random noise and power-line harmonics, resulting in reduced quality of received data. Achieving reliable extraction of MRS signals under strong noise is difficult. To solve this problem, we propose a matching pursuit algorithm based on sparse decomposition theory for data noise suppression and MRS signal extraction. In accordance with the characteristics of the signal and noise, an oscillating atomic library is constructed as a sparse dictionary to realize signal sparse decomposition. A two-step denoising strategy is proposed to reconstruct the power-line harmonics and then extract the MRS signal. We simulated synthetic data with different signal-to-noise ratios (SNRs), relaxation times, and Larmor frequencies. Our results show that the proposed algorithm can effectively remove power-line harmonics and reduce random noise. SNR is significantly improved by up to 35.6 dB after denoising. The effectiveness and superiority of the proposed algorithm are further verified by the measured data and through comparison with the singular spectrum analysis algorithm and harmonic modeling cancellation algorithm.

APA, Harvard, Vancouver, ISO, and other styles

27

Mancho, Ana M., Emilio Hernández-García, Cristóbal López, Antonio Turiel, Stephen Wiggins, and Vicente Pérez-Muñuzuri. "Preface: Current perspectives in modelling, monitoring, and predicting geophysical fluid dynamics." Nonlinear Processes in Geophysics 25, no. 1 (February 23, 2018): 125–27. http://dx.doi.org/10.5194/npg-25-125-2018.

Full text

Abstract:

Abstract. The third edition of the international workshop Nonlinear Processes in Oceanic and Atmospheric Flows was held at the Institute of Mathematical Sciences (ICMAT) in Madrid from 6 to 8 July 2016. The event gathered oceanographers, atmospheric scientists, physicists, and applied mathematicians sharing a common interest in the nonlinear dynamics of geophysical fluid flows. The philosophy of this meeting was to bring together researchers from a variety of backgrounds into an environment that favoured a vigorous discussion of concepts across different disciplines. The present Special Issue on Current perspectives in modelling, monitoring, and predicting geophysical fluid dynamics contains selected contributions, mainly from attendants of the workshop, providing an updated perspective on modelling aspects of geophysical flows as well as issues on prediction and assimilation of observational data and novel tools for describing transport and mixing processes in these contexts. More details on these aspects are discussed in this preface.

APA, Harvard, Vancouver, ISO, and other styles

28

Goncharov, V., and V. Pavlov. "On the Hamiltonian approach: Applications to geophysical flows." Nonlinear Processes in Geophysics 5, no. 4 (December 31, 1998): 219–40. http://dx.doi.org/10.5194/npg-5-219-1998.

Full text

Abstract:

Abstract. This paper presents developments of the Harniltonian Approach to problems of fluid dynamics, and also considers some specific applications of the general method to hydrodynamical models. Nonlinear gauge transformations are found to result in a reduction to a minimum number of degrees of freedom, i.e. the number of pairs of canonically conjugated variables used in a given hydrodynamical system. It is shown that any conservative hydrodynamic model with additional fields which are in involution may be always reduced to the canonical Hamiltonian system with three degrees of freedom only. These gauge transformations are associated with the law of helicity conservation. Constraints imposed on the corresponding Clebsch representation are determined for some particular cases, such as, for example. when fluid motions develop in the absence of helicity. For a long time the process of the introduction of canonical variables into hydrodynamics has remained more of an intuitive foresight than a logical finding. The special attention is allocated to the problem of the elaboration of the corresponding regular procedure. The Harniltonian Approach is applied to geophysical models including incompressible (3D and 2D) fluid motion models in curvilinear and lagrangian coordinates. The problems of the canonical description of the Rossby waves on a rotating sphere and of the evolution of a system consisting of N singular vortices are investigated.

APA, Harvard, Vancouver, ISO, and other styles

29

Pitman, E. Bruce, and Long Le. "A two-fluid model for avalanche and debris flows." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 363, no. 1832 (July 2005): 1573–601. http://dx.doi.org/10.1098/rsta.2005.1596.

Full text

Abstract:

Geophysical mass flows—debris flows, avalanches, landslides—can contain O (10 6 –10 10 ) m 3 or more of material, often a mixture of soil and rocks with a significant quantity of interstitial fluid. These flows can be tens of meters in depth and hundreds of meters in length. The range of scales and the rheology of this mixture presents significant modelling and computational challenges. This paper describes a depth-averaged ‘thin layer’ model of geophysical mass flows containing a mixture of solid material and fluid. The model is derived from a ‘two-phase’ or ‘two-fluid’ system of equations commonly used in engineering research. Phenomenological modelling and depth averaging combine to yield a tractable set of equations, a hyperbolic system that describes the motion of the two constituent phases. If the fluid inertia is small, a reduced model system that is easier to solve may be derived.

APA, Harvard, Vancouver, ISO, and other styles

30

Vanneste, J. "Balance and Spontaneous Wave Generation in Geophysical Flows." Annual Review of Fluid Mechanics 45, no. 1 (January 3, 2013): 147–72. http://dx.doi.org/10.1146/annurev-fluid-011212-140730.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Califano, Francesco. "A numerical algorithm for geophysical and astrophysical inhomogeneous fluid flows." Computer Physics Communications 99, no. 1 (December 1996): 29–42. http://dx.doi.org/10.1016/s0010-4655(96)00117-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Duan, Jinqiao, and Beniamin Goldys. "Ergodicity of stochastically forced large scale geophysical flows." International Journal of Mathematics and Mathematical Sciences 28, no. 6 (2001): 313–20. http://dx.doi.org/10.1155/s0161171201012443.

Full text

Abstract:

We investigate the ergodicity of 2D large scale quasigeostrophic flows under random wind forcing. We show that the quasigeostrophic flows are ergodic under suitable conditions on the random forcing and on the fluid domain, and under no restrictions on viscosity, Ekman constant or Coriolis parameter. When these conditions are satisfied, then for any observable of the quasigeostrophic flows, its time average approximates the statistical ensemble average, as long as the time interval is sufficiently long.

APA, Harvard, Vancouver, ISO, and other styles

33

Rypina, Irina I., Stefan G. Llewellyn Smith, and Larry J. Pratt. "Connection between encounter volume and diffusivity in geophysical flows." Nonlinear Processes in Geophysics 25, no. 2 (April 4, 2018): 267–78. http://dx.doi.org/10.5194/npg-25-267-2018.

Full text

Abstract:

Abstract. Trajectory encounter volume – the volume of fluid that passes close to a reference fluid parcel over some time interval – has been recently introduced as a measure of mixing potential of a flow. Diffusivity is the most commonly used characteristic of turbulent diffusion. We derive the analytical relationship between the encounter volume and diffusivity under the assumption of an isotropic random walk, i.e., diffusive motion, in one and two dimensions. We apply the derived formulas to produce maps of encounter volume and the corresponding diffusivity in the Gulf Stream region of the North Atlantic based on satellite altimetry, and discuss the mixing properties of Gulf Stream rings. Advantages offered by the derived formula for estimating diffusivity from oceanographic data are discussed, as well as applications to other disciplines.

APA, Harvard, Vancouver, ISO, and other styles

34

Grishchenko, Vadim Aleksandrovich, Vyacheslav Sharifullovich Mukhametshin, and Ruslan Uralovich Rabaev. "Geological Structure Features of Carbonate Formations and Their Impact on the Efficiency of Developing Hydrocarbon Deposits." Energies 15, no. 23 (November 28, 2022): 9002. http://dx.doi.org/10.3390/en15239002.

Full text

Abstract:

The development of deposits with a complex geological structures is often accompanied by a set of problems associated with optimal decision making. The efficiency of the entire development system depends on the completeness and the quality of the analysis of reservoir parameters. This paper presents methodological approaches for the study of carbonate deposits, and the development of further steps to increase the efficiency of reserve recovery. The secondary transformation of reservoir rocks, resulting in channels of increased conductivity, cracks, and caverns, plays a special role in the nature of the recovery of hydrocarbon reserves from such deposits. Secondary cavernosity leads to violations of the linear laws of fluid filtration in a porous medium, and complicates the field performance prediction based on geological and hydrodynamic modeling. The studied geological structure was detailed using the example of carbonate deposits composed of oil and water- saturated formations, taking into account the results of core studies and the interpretation of geophysical well studies. Furthermore, the parameters of production wells made it possible to confirm that the oil saturated and underlying water saturated formations have hydrodynamic connectivity due to the presence of vertical micro cracks. At the same time, the thickness of the bridge between the reservoirs directly affects the initial water cutting of well production, and further growth dynamics of the water ratio are associated with the structural factors determining the initial oil content of the reservoir. The combination of the obtained dependencies and the distribution model of the reservoir properties along the area made it possible to build a complex map reflecting the predicted development efficiency in certain areas. The integration of the results of various field studies on the injection well stock established that a significant part of the water flows was injected into the water saturated formation, which reduces the efficiency of formation pressure maintenance in the target formation. As a result, in order to reduce the low efficiency injection volume, switching to a more rigid waterflooding system, in terms of the ratio of production and injection wells, is proposed with a further decrease in the injection pressure inside the wells.

APA, Harvard, Vancouver, ISO, and other styles

35

Accary, Gilbert, Patrick Bontoux, and Bernard Zappoli. "Convection in a supercritical fluid: A reduced model for geophysical flows." Physics of Fluids 19, no. 1 (January 2007): 014104. http://dx.doi.org/10.1063/1.2432159.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Duan, Jinqiao, Christian Pötzsche, and Stefan Siegmund. "Slow integral manifolds for Lagrangian fluid dynamics in unsteady geophysical flows." Physica D: Nonlinear Phenomena 233, no. 1 (September 2007): 73–82. http://dx.doi.org/10.1016/j.physd.2007.06.016.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Chu, Jifeng. "Monotone solutions of a nonlinear differential equation for geophysical fluid flows." Nonlinear Analysis 166 (January 2018): 144–53. http://dx.doi.org/10.1016/j.na.2017.10.010.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Deleersnijder, E., and G. Lebon. "Enforcing the continuity equation in numerical models of geophysical fluid flows." Applied Mathematics Letters 14, no. 7 (October 2001): 867–73. http://dx.doi.org/10.1016/s0893-9659(01)00057-x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Zhang, Wenlin, Michal Fečkan, and JinRong Wang. "Positive solutions to integral boundary value problems from geophysical fluid flows." Monatshefte für Mathematik 193, no. 4 (September 22, 2020): 901–25. http://dx.doi.org/10.1007/s00605-020-01467-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Song, D., C. E. Choi, C. W. W. Ng, and G. G. D. Zhou. "Geophysical flows impacting a flexible barrier: effects of solid-fluid interaction." Landslides 15, no. 1 (July 16, 2017): 99–110. http://dx.doi.org/10.1007/s10346-017-0856-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Iornumbe, SI, GCE Mbah, and RA Chia. "Mathematical Model of Geophysical Fluid Flow over Variable Bottom Topography." NIGERIAN ANNALS OF PURE AND APPLIED SCIENCES 3, no. 2 (July 22, 2020): 186–99. http://dx.doi.org/10.46912/napas.163.

Full text

Abstract:

In this paper, the bottom topography of a geophysical fluid flow is modelled in the presence of Coriolis force by the nonlinear shallow water equations. These equations, which are a system of three partial differential equations in two space dimensions, are solved using the perturbation method. The Effects of the Coriolis force and the bottom topography for particular initial flows on the velocity components and different kind of flow patterns possible in geophysical fluid flow have been studied and the results illustrated graphically.

APA, Harvard, Vancouver, ISO, and other styles

42

Rycroft, M. J. "Theoretical Geophysical Fluid Dynamics,." Journal of Atmospheric and Terrestrial Physics 56, no. 11 (September 1994): 1529. http://dx.doi.org/10.1016/0021-9169(94)90119-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Córdoba, G., M. F. Sheridan, and E. B. Pitman. "TITAN2F: a pseudo-3-D model of 2-phase debris flows." Natural Hazards and Earth System Sciences Discussions 3, no. 6 (June 12, 2015): 3789–822. http://dx.doi.org/10.5194/nhessd-3-3789-2015.

Full text

Abstract:

Abstract. Debris flows, avalanches, landslides, and other geophysical mass flows can contain O(106–1010) m3 or more of material. These flows commonly consist of mixture of soil and rocks with a significant quantity of interstitial fluid. They can be tens of meters deep, and their runouts can extend many kilometers. The complicated rheology of such a mixture challenges every constitutive model that can reasonably be applied; the range of length and timescales involved in such mass flows challenges the computational capabilities of existing systems.This paper extends recent efforts to develop a depth averaged "thin layer" model for geophysical mass flows that contain a mixture of solid material and fluid. Concepts from the engineering community are integrated with phenomenological findings in geo-science, resulting in a theory that accounts for the principal solid and fluid forces as well as interactions between the phases, across a wide range of solid volume fraction. A principal contribution here is to present drag and phase interaction terms that comport with the literature in geo-sciences. The program predicts the evolution of the concentration and dynamic pressure. The theory is validated with with data from one dimensional dam break solutions and it is verified with data from artificial channel experiments.

APA, Harvard, Vancouver, ISO, and other styles

44

Iornumbe, SI, T. Tivde, and RA Chia. "A Mathematical Model of Stratified Geophysical Fluid Flows Over Variable Bottom Topography." NIGERIAN ANNALS OF PURE AND APPLIED SCIENCES 3, no. 3b (November 15, 2020): 112–37. http://dx.doi.org/10.46912/napas.202.

Full text

Abstract:

In this paper, a mathematical model of stratified geophysical fluid flow over variable bottom topography was derived for shallow water. The equations are derived from the principles of conservation of mass and conservation of momentum. The force acting on the fluid is gravity, represented by the gravitational constant. A system of six nonlinear partial differential equations was obtained as the model equations. The solutions of these models were obtained using perturbation method. The presence of the coriolis force in the shallow water equations were shown as the causes of the deflection of fluid parcels in the direction of wave motion and causes gravity waves to disperse. As water depth decreases due to varied bottom topography, the wave amplitude were shown to increase while the wavelength and wave speed decreases resulting in overturning of the wave. The results are presented graphically.

APA, Harvard, Vancouver, ISO, and other styles

45

Shivamoggi, Bhimsen K. "A generalized class of nonlinear Rossby localized structures in geophysical fluid flows." Chaos, Solitons & Fractals 14, no. 3 (August 2002): 469–77. http://dx.doi.org/10.1016/s0960-0779(01)00218-1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

McKiver, William J. "The Ellipsoidal Vortex: A Novel Approach to Geophysical Turbulence." Advances in Mathematical Physics 2015 (2015): 1–9. http://dx.doi.org/10.1155/2015/613683.

Full text

Abstract:

We review the development of the ellipsoidal vortex model within the field of geophysical fluid dynamics. This vortex model is built on the classical potential theory of ellipsoids and applies to large-scale fluid flows, such as those found in the atmosphere and oceans, where the dynamics are strongly affected by the Earth's rotation. In this large-scale limit the governing equations reduce to the quasi-geostrophic system, where all the dynamics depends on a single scalar field, the potential vorticity, which is a dynamical marker for vortices. The solution of this system is achieved by the inversion of a Poisson equation, that in the case of an ellipsoidal vortex can be solved exactly. From this ellipsoidal solution equilibria have been determined and their stability properties have been studied. Many studies have shown that this ellipsoidal vortex model, while being conceptually simple, is an extremely powerful tool in eliciting some of the fundamental characteristics of turbulent geophysical flows.

APA, Harvard, Vancouver, ISO, and other styles

47

Duck, Peter W. "Spin-up problems of stratified rotating flows inside containers." Journal of Fluid Mechanics 712 (November 28, 2012): 3–6. http://dx.doi.org/10.1017/jfm.2012.444.

Full text

Abstract:

AbstractRotating, stratified flows are important in a wide variety of both geophysical and engineering applications. Whilst ‘steady state’ flows of this type are generally very simple (in effect, rigid body rotation), the effect of abruptly altering (even a little) the rotation rate can induce significant temporal flow disruptions, made all the more complicated when the fluid is bounded inside a closed finite container, a problem studied both experimentally and theoretically by Foster & Munro (J. Fluid Mech., this issue, vol. 712, 2012, pp. 7–40).

APA, Harvard, Vancouver, ISO, and other styles

48

Kurgansky, M. V. "On statistical equilibrium in helical fluid flows." Nonlinear Processes in Geophysics 13, no. 2 (June 2, 2006): 161–66. http://dx.doi.org/10.5194/npg-13-161-2006.

Full text

Abstract:

Abstract. The statistical mechanics of 3-D helical flows is re-examined for a continuum truncated at a top wavenumber. Based on the principle of equipartition of the flow enstrophy between helical modes, the emerging (i) energy spectrum law "–2" and (ii) formal mathematical analogy between the helicity and the thermodynamic entropy are discussed. It is noted that the "–2" scaling law is consistent with both spectral equilibrium and spectral cascade paradigms. In an attempt to apply the obtained results to a turbulent flow regime within the Earth's outer liquid core, where the net helicity of a turbulent flow component is presumably explained by Earth's rotation, it has been noticed that it is the energy spectral law "–1", but not "–2", which is likely realized there and within the logarithmic accuracy corresponds to the case of the velocity structure function [u(l)]2 independency on the spatial scale l, the latter is consistent with observations. It is argued that the "–1" scaling law can also be interpreted in terms of the spectral equilibrium and it is emphasized that the causes of the likely dominance of the spectral law "–1" over the spectral law "–2" in this geophysical application deserve further investigation and clarification.

APA, Harvard, Vancouver, ISO, and other styles

49

Zidikheri, Meelis J., and Jorgen S. Frederiksen. "Stochastic subgrid-scale modelling for non-equilibrium geophysical flows." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1910 (January 13, 2010): 145–60. http://dx.doi.org/10.1098/rsta.2009.0192.

Full text

Abstract:

Methods motivated by non-equilibrium statistical mechanics of turbulence are applied to solve an important practical problem in geophysical fluid dynamics, namely the parametrization of subgrid-scale eddies needed in large-eddy simulations (LESs). A direct stochastic modelling scheme that is closely related to techniques based on statistical closure theories, but which is more generally applicable to complex models, is employed. Here, we parametrize the effects of baroclinically unstable subgrid-scale eddies in idealized flows with broad similarities to the Antarctic Circumpolar Current of the Southern Ocean. The subgrid model represents the effects of the unresolved eddies through a generalized Langevin equation. The subgrid dissipation and stochastic forcing covariance matrices as well as the mean subgrid forcing required by the LES model are obtained from the statistics of a high resolution direct numerical simulation (DNS). We show that employing these parametrizations leads to LES in close agreement with DNS.

APA, Harvard, Vancouver, ISO, and other styles

50

Chakraborty, Rishiraj, Aaron Coutino, and Marek Stastna. "Particle clustering and subclustering as a proxy for mixing in geophysical flows." Nonlinear Processes in Geophysics 26, no. 3 (September 16, 2019): 307–24. http://dx.doi.org/10.5194/npg-26-307-2019.

Full text

Abstract:

Abstract. The Eulerian point of view is the traditional theoretical and numerical tool to describe fluid mechanics. Some modern computational fluid dynamics codes allow for the efficient simulation of particles, in turn facilitating a Lagrangian description of the flow. The existence and persistence of Lagrangian coherent structures in fluid flow has been a topic of considerable study. Here we focus on the ability of Lagrangian methods to characterize mixing in geophysical flows. We study the instability of a strongly non-linear double-jet flow, initially in geostrophic balance, which forms quasi-coherent vortices when subjected to ageostrophic perturbations. Particle clustering techniques are applied to study the behavior of the particles in the vicinity of coherent vortices. Changes in inter-particle distance play a key role in establishing the patterns in particle trajectories. This paper exploits graph theory in finding particle clusters and regions of dense interactions (also known as subclusters). The methods discussed and results presented in this paper can be used to identify mixing in a flow and extract information about particle behavior in coherent structures from a Lagrangian point of view.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Geophysical and environmental fluid flows'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles