Laboratory experiments on rosette diffusers for dense concentrate disposal from seawater desalina... more Laboratory experiments on rosette diffusers for dense concentrate disposal from seawater desalination plants are reported. The rosettes each had four nozzles pointing upwards at 60° and arranged 90° apart in planform. Single and multiple risers in two planform orientations in stationary environments were tested for various riser spacing. Three-dimensional laser-induced fluorescence (3DLIF) was used to map tracer concentration fields from which the dilution, length, and thickness at the end of the near field were obtained. The effect of riser spacing depends on the dimensionless parameter s r =dF, where s r is the riser spacing, d the nozzle diameter, and F the jet densimetric Froude number. For s r =dF > ∼2, the results were independent of riser spacing but the near-field dilution was approximately 27% lower than it is for a single jet. For s r =dF < ∼2 the dilution, near-field length decrease, and empirical equations for their dependence on spacing were proposed. Dilution is less dependent on riser spacing than might be expected based on multiport diffuser results. This is because the jets from a rosette diffuser do not readily merge and block penetration of entrained diluting water, so the diffuser can be shorter for the same dilution.
ABSTRACT We propose a generalization of Hopf fibrations to quotient the streamwise translation sy... more ABSTRACT We propose a generalization of Hopf fibrations to quotient the streamwise translation symmetry of turbulent pipe flows viewed as dynamical systems. In particular, we exploit the geometric structure of the associate high dimensional state space, which is that of a principal fiber bundle. The relation between the comoving frame velocity $U_{d}$ associated with the dynamical phase of an orbit in the bundle and the Taylor&amp;#39;s hypothesis is investigated. As an application, Laser-Induced-Fluorescence techniques are exploited to capture planar fluorescent dye concentration fields tracing a turbulent pipe flow at the bulk Reynolds number $\mathfrak{\mathsf{Re}}=3200$. The symmetry reduction analysis of the experimental data reveals that the speed $u$ of dye concentration bursts is associated with the dynamical and geometric phases of the corresponding orbits in the fiber bundle. In particular, in the symmetry-reduced frame we unveil a pattern-changing dynamics of the passive scalar structures, which explains the observed speed $u\approx U_{d}+U_{g}$ of intense bursting events in terms of the geometric phase velocity $U_{g}\approx0.43U_{d}$ associated with the orbits in the bundle.
Direct discharges of municipal and industrial waste waters into water bodies through marine outfa... more Direct discharges of municipal and industrial waste waters into water bodies through marine outfalls are considered as a common way to dispose the generated waste in coastal zones. Marine discharge, intensifying flow mixing and entrainment, decrease the concentration of polutant up to accepted concentration and meet the guideline values and to make possible continues discharge of flow into matine environment. During last years due to quick development of coastal desalination plants, surface discharge of preduced salty ...
In this paper, a simple methodology based on multivariate analysis is developed to create a groun... more In this paper, a simple methodology based on multivariate analysis is developed to create a groundwater quality index (GWQI). The methodology is based on three general stages, selection, standardization and aggregation, to develop a groundwater quality index in an area using regional and local standards. In this method, through selecting a set of similar parameters, standard values of the parameters are obtained by dividing the averaged concentration of parameters by their maximum allowable concentration cited in ...
In the present study, adsorption of dissolved Cadmium (Cd) onto walnut and almond shell charcoal ... more In the present study, adsorption of dissolved Cadmium (Cd) onto walnut and almond shell charcoal and the standard granular activated carbon (GAC) has been investigated and compared. The effect of pH value, initial concentration of dissolved Cadmium and amount of adsorbent on the adsorption of Cd by the mentioned adsorbents were investigated. Results showed that the adsorption process was highly dependent on pH. Maximum Cd removal was achieved when the final pH of the mixture fell within 6.5-7. ...
A series of laboratory experiments have been conducted for negatively buoyant effluents discharge... more A series of laboratory experiments have been conducted for negatively buoyant effluents discharged through a protruding surface channel into unstratified stagnant water. The mixing behavior of the flow has been analyzed using digital video recordings of the dye colored discharge together with micro conductivity probe measurements. Plume trajectories and geometries have been determined by image processing and dilutions from the conductivity probe data. Comparison of non-dimensional results for plume characteristics showed ...
Abstract Surface discharges of negatively buoyant jets into moving ambient water create a range o... more Abstract Surface discharges of negatively buoyant jets into moving ambient water create a range of complex flow patterns. These complexities arise through the interplay between the discharge&amp;amp;amp;#x27;s initial fluxes and the motion of the ambient current. In this study a series of laboratory experiments were conducted for negatively buoyant surface discharges into crossflow to investigate flow patterns under different discharge and ambient conditions. The results compared with simulations of the CORMIX model, an expert system for ocean ...
We propose and apply a Fourier-based symmetry-reduction scheme to remove, or quotient, the stream... more We propose and apply a Fourier-based symmetry-reduction scheme to remove, or quotient, the streamwise translation symmetry of laser-induced-fluorescence measurements of turbulent pipe flows that are viewed as dynamical systems in a high-dimensional state space. We also explain the relation between Taylor’s hypothesis and the comoving frame velocity Ud of the turbulent orbit in state space. In particular, in physical space we observe flow structures that deform as they advect downstream at a speed that differs significantly from Ud. Indeed, the symmetry-reduction analysis of planar dye concentration fields at Reynolds number Re = 3200 reveals that the speed u at which high-concentration peaks advect is roughly 1.43 times Ud. In a physically meaningful symmetry-reduced frame, the excess speed u-Ud = 0.43 Ud can be explained in terms of the so-called geometric phase velocity Ug associated with the orbit in state space. The ‘self-propulsion velocity’ Ug is induced by the shape-changing dynamics of passive scalar structures observed in the symmetry-reduced frame, in analogy with that of a swimmer at flow Reynolds numbers.
Extensive Experiments on inclined dense jets typical of brine discharges into shallow water are r... more Extensive Experiments on inclined dense jets typical of brine discharges into shallow water are reported. The experiments were conducted with nozzles oriented at 30°, 45°, and 60° to the horizontal and the spatial variations of tracer concentrations were measured by three-dimensional laser-induced fluorescence (3DLIF). Three flow regimes were identified: deep water, surface contact, and shallow water. The regimes depend on the value of dF=H, where d is the nozzle diameter, F the jet densimetric Froude number, and H the water depth; criteria were presented for the transitions between them. Flow images revealed complex three-dimensional interactions with the free surface, especially for steep nozzle angles in shallow water. Dilutions at critical points and their locations were measured. For deep water, all results followed those previously reported for fully submerged jets. As the depth decreases (or dF=H increases) to the surface contact regime, dilutions begin to decrease. Tracer concentration profiles are truncated at the water surface and in shallow water resemble half-Gaussian profiles similar to those of wall jets. The jets can cling to the water surface, although the locations of the bottom impact point and near-field length are not significantly affected by the water surface. In deep water and surface contact regimes, the impact point and near-field dilutions are highest for 60° nozzles. As the depth decreases further, however, the dilutions for the three nozzle angles become approximately equal, until, for shallow water, the 30°-nozzle gives slightly higher dilution. The 30°-nozzle may be preferable for this case because there is less surface interaction and, therefore, less visual impact on the water surface. Previous recommendations that dense jets be submerged so that the rise height to the jet’s upper boundary be less than 75% of the water depth to avoid surface effects appear to be overly conservative and the present results suggest that the rise can be as much as 90% of the water depth for all angles with no deleterious effect on dilution.
Laboratory experiments on single dense jets oriented at angles from 15° to 85° to the horizontal ... more Laboratory experiments on single dense jets oriented at angles from 15° to 85° to the horizontal are reported. The major flow properties were measured by laser-induced fluorescence at the maximum rise height, impact point, and, for the first time, at the end of the near field. The impact point dilution was insensitive to nozzle angle over the range of about 45–65°. Because the additional mixing that occurred in the spreading layer beyond the impact point depended on nozzle angle, the near-field dilution was more sensitive to nozzle orientation and was highest for 60°, consistent with generally accepted design practice. Bottom boundary effects on dilution were also addressed. Along the jet centerline, time-average dilution first increased and then actually decreased in a thin layer up to the wall. The concentration increase near the bed is due to an increase in turbulent intermittency and accumulation of more saline fluid elements at the bed. The presence of this layer may explain wide discrepancies in reported dilutions near the boundary and may be environmentally important due to exposure of benthic organisms and sea grasses to high salinity. It may not persist, however, as it can be swept up by vortices that propagate radially away from the impact point. The vortices entrain ambient fluid leading to increased dilution, but they eventually collapse under their self-induced density stratification, marking the end of the near field.
Comprehensive laboratory experiments on multiport diffusers for dense effluents such as brine int... more Comprehensive laboratory experiments on multiport diffusers for dense effluents such as brine into stationary receiving waters are reported. Tracer concentration fields were mapped in three dimensions by laser-induced fluorescence (3DLIF). The effect of port spacing is described by s=dF where s is the port spacing, d the nozzle diameter, and F the jet densimetric Froude number. For s=dF > ∼2, the jets did not merge, and the results followed expected asymptotic solutions for single jets. For s=dF < 2 the jets merged, but did not follow expected asymptotic line source solutions. As the port spacing was reduced, the rise height and other geometrical variables decreased. The dilutions also decreased, but much more rapidly than predicted. These were caused by Coanda effects and merging. The Coanda effect caused an under pressure on the interior jet surfaces which caused them to curve more sharply inwards. This shortened their trajectories, reducing the external surface area available for entrainment. Jet merging restricted entrainment of clear water to the inner surfaces and exacerbated the Coanda effect. The implications for numerical modeling are discussed. Integral entrainment models that assume unrestricted entrainment water, neglect reentrainment, and neglect dynamic interaction (Coanda effect) between jets may significantly overestimate dilution. Insight into port spacing effects can be obtained from studies on positively buoyant jets. To prevent reduction in dilution attributable to restricted entrainment, it is recommended to maintain adequate port spacing so that s=dF > ∼2.
Abstract Direct discharges of municipal and industrial waste waters into water bodies through mar... more Abstract Direct discharges of municipal and industrial waste waters into water bodies through marine outfalls are considered as a common way to dispose the generated waste in coastal zones. Marine discharge, intensifying flow mixing and entrainment, decrease the concentration of polutant up to accepted concentration and meet the guideline values and to make possible continues discharge of flow into matine environment.
Abstract In this paper, a simple methodology based on multivariate analysis is developed to creat... more Abstract In this paper, a simple methodology based on multivariate analysis is developed to create a groundwater quality index (GWQI). The methodology is based on three general stages, selection, standardization and aggregation, to develop a groundwater quality index in an area using regional and local standards.
A series of laboratory experiments have been conducted for negatively buoyant effluents discharge... more A series of laboratory experiments have been conducted for negatively buoyant effluents discharged through a protruding surface channel into unstratified stagnant water. The mixing behavior of the flow has been analyzed using digital video recordings of the dye colored discharge together with micro conductivity probe measurements. Plume trajectories and geometries have been determined by image processing and dilutions from the conductivity probe data. Comparison of non-dimensional results for plume characteristics showed similar features to those of submerged positively buoyant jets. However, notable differences are observed in the flow behavior prior to it plunging away from the free surface. As expected the overall dilution is lower when compared to submerged discharges. These differences are quantified and the new results provide information that can be used for the preliminary design of dense surface discharges.
Surface discharges of negatively buoyant jets into moving ambient water create a range of complex... more Surface discharges of negatively buoyant jets into moving ambient water create a range of complex flow patterns. These complexities arise through the interplay between the discharge's initial fluxes and the motion of the ambient current. In this study a series of laboratory experiments were conducted for negatively buoyant surface discharges into crossflow to investigate flow patterns under different discharge and ambient conditions. The results compared with simulations of the CORMIX model, an expert system for ocean outfall design. In CORMIX, the simulation module DHYDRO for dense discharges has been used. Finally the flow different patterns were arranged in a dimensionless diagram to propose a modified flow classification system with new criteria.
Surface discharges of negatively buoyant jets into moving ambient water create a range of complex... more Surface discharges of negatively buoyant jets into moving ambient water create a range of complex flow patterns.These complexities arise through the interplay between the discharge’s initial fluxes and the motion of the ambient current. In this study a series of laboratory experiments were conducted for negatively buoyant surface discharges into crossflow to investigate flow patterns under different discharge and ambient conditions. The results compared with simulations of the CORMIX model, an expert system for ocean outfall design. In CORMIX, the simulation module DHYDRO for dense discharges has been used. Finally the flow different patterns were arranged in a dimensionless diagram to propose a modified flowclassification system with new criteria
Ports’ activities could result in oil spills occurrences and oil pollution in different ways incl... more Ports’ activities could result in oil spills occurrences and oil pollution in different ways including the discharges of ships’ oily wastes, discharges of oily ballast water and leaks at oil terminals. In this paper, using the results of the analyses of the hydrocarbon compounds in the samples collected from the sediments in the Anzali Port in the Caspian Sea in Iran, the levels of oil pollution in the sediments, in terms of Total Petroleum Hydrocarbons and Petroleum Aromatic Hydrocarbons, are studied. Also using a number of existing biomarker profiles, the sources of aliphatic hydrocarbons were investigated. The concentration of Total Petroleum Hydrocarbons ranged between 7.6 to 29 mg/kg indicated that oil pollution content of the sediments in the area is at a low to medium level. Also the concentrations of PAHs in the sediments were very low (0.62 – 6.12 ng/g). This indicated that the sediments sampled in the study area can be considered unpolluted in terms of aromatic hydrocarbons. Analyses of the samples using a number of biomarkers showed a combination of natural (marine and terrestrial) and petrogenic hydrocarbons in the sediments in the Anzali Port area.
Laboratory experiments on rosette diffusers for dense concentrate disposal from seawater desalina... more Laboratory experiments on rosette diffusers for dense concentrate disposal from seawater desalination plants are reported. The rosettes each had four nozzles pointing upwards at 60° and arranged 90° apart in planform. Single and multiple risers in two planform orientations in stationary environments were tested for various riser spacing. Three-dimensional laser-induced fluorescence (3DLIF) was used to map tracer concentration fields from which the dilution, length, and thickness at the end of the near field were obtained. The effect of riser spacing depends on the dimensionless parameter s r =dF, where s r is the riser spacing, d the nozzle diameter, and F the jet densimetric Froude number. For s r =dF > ∼2, the results were independent of riser spacing but the near-field dilution was approximately 27% lower than it is for a single jet. For s r =dF < ∼2 the dilution, near-field length decrease, and empirical equations for their dependence on spacing were proposed. Dilution is less dependent on riser spacing than might be expected based on multiport diffuser results. This is because the jets from a rosette diffuser do not readily merge and block penetration of entrained diluting water, so the diffuser can be shorter for the same dilution.
ABSTRACT We propose a generalization of Hopf fibrations to quotient the streamwise translation sy... more ABSTRACT We propose a generalization of Hopf fibrations to quotient the streamwise translation symmetry of turbulent pipe flows viewed as dynamical systems. In particular, we exploit the geometric structure of the associate high dimensional state space, which is that of a principal fiber bundle. The relation between the comoving frame velocity $U_{d}$ associated with the dynamical phase of an orbit in the bundle and the Taylor&amp;#39;s hypothesis is investigated. As an application, Laser-Induced-Fluorescence techniques are exploited to capture planar fluorescent dye concentration fields tracing a turbulent pipe flow at the bulk Reynolds number $\mathfrak{\mathsf{Re}}=3200$. The symmetry reduction analysis of the experimental data reveals that the speed $u$ of dye concentration bursts is associated with the dynamical and geometric phases of the corresponding orbits in the fiber bundle. In particular, in the symmetry-reduced frame we unveil a pattern-changing dynamics of the passive scalar structures, which explains the observed speed $u\approx U_{d}+U_{g}$ of intense bursting events in terms of the geometric phase velocity $U_{g}\approx0.43U_{d}$ associated with the orbits in the bundle.
Direct discharges of municipal and industrial waste waters into water bodies through marine outfa... more Direct discharges of municipal and industrial waste waters into water bodies through marine outfalls are considered as a common way to dispose the generated waste in coastal zones. Marine discharge, intensifying flow mixing and entrainment, decrease the concentration of polutant up to accepted concentration and meet the guideline values and to make possible continues discharge of flow into matine environment. During last years due to quick development of coastal desalination plants, surface discharge of preduced salty ...
In this paper, a simple methodology based on multivariate analysis is developed to create a groun... more In this paper, a simple methodology based on multivariate analysis is developed to create a groundwater quality index (GWQI). The methodology is based on three general stages, selection, standardization and aggregation, to develop a groundwater quality index in an area using regional and local standards. In this method, through selecting a set of similar parameters, standard values of the parameters are obtained by dividing the averaged concentration of parameters by their maximum allowable concentration cited in ...
In the present study, adsorption of dissolved Cadmium (Cd) onto walnut and almond shell charcoal ... more In the present study, adsorption of dissolved Cadmium (Cd) onto walnut and almond shell charcoal and the standard granular activated carbon (GAC) has been investigated and compared. The effect of pH value, initial concentration of dissolved Cadmium and amount of adsorbent on the adsorption of Cd by the mentioned adsorbents were investigated. Results showed that the adsorption process was highly dependent on pH. Maximum Cd removal was achieved when the final pH of the mixture fell within 6.5-7. ...
A series of laboratory experiments have been conducted for negatively buoyant effluents discharge... more A series of laboratory experiments have been conducted for negatively buoyant effluents discharged through a protruding surface channel into unstratified stagnant water. The mixing behavior of the flow has been analyzed using digital video recordings of the dye colored discharge together with micro conductivity probe measurements. Plume trajectories and geometries have been determined by image processing and dilutions from the conductivity probe data. Comparison of non-dimensional results for plume characteristics showed ...
Abstract Surface discharges of negatively buoyant jets into moving ambient water create a range o... more Abstract Surface discharges of negatively buoyant jets into moving ambient water create a range of complex flow patterns. These complexities arise through the interplay between the discharge&amp;amp;amp;#x27;s initial fluxes and the motion of the ambient current. In this study a series of laboratory experiments were conducted for negatively buoyant surface discharges into crossflow to investigate flow patterns under different discharge and ambient conditions. The results compared with simulations of the CORMIX model, an expert system for ocean ...
We propose and apply a Fourier-based symmetry-reduction scheme to remove, or quotient, the stream... more We propose and apply a Fourier-based symmetry-reduction scheme to remove, or quotient, the streamwise translation symmetry of laser-induced-fluorescence measurements of turbulent pipe flows that are viewed as dynamical systems in a high-dimensional state space. We also explain the relation between Taylor’s hypothesis and the comoving frame velocity Ud of the turbulent orbit in state space. In particular, in physical space we observe flow structures that deform as they advect downstream at a speed that differs significantly from Ud. Indeed, the symmetry-reduction analysis of planar dye concentration fields at Reynolds number Re = 3200 reveals that the speed u at which high-concentration peaks advect is roughly 1.43 times Ud. In a physically meaningful symmetry-reduced frame, the excess speed u-Ud = 0.43 Ud can be explained in terms of the so-called geometric phase velocity Ug associated with the orbit in state space. The ‘self-propulsion velocity’ Ug is induced by the shape-changing dynamics of passive scalar structures observed in the symmetry-reduced frame, in analogy with that of a swimmer at flow Reynolds numbers.
Extensive Experiments on inclined dense jets typical of brine discharges into shallow water are r... more Extensive Experiments on inclined dense jets typical of brine discharges into shallow water are reported. The experiments were conducted with nozzles oriented at 30°, 45°, and 60° to the horizontal and the spatial variations of tracer concentrations were measured by three-dimensional laser-induced fluorescence (3DLIF). Three flow regimes were identified: deep water, surface contact, and shallow water. The regimes depend on the value of dF=H, where d is the nozzle diameter, F the jet densimetric Froude number, and H the water depth; criteria were presented for the transitions between them. Flow images revealed complex three-dimensional interactions with the free surface, especially for steep nozzle angles in shallow water. Dilutions at critical points and their locations were measured. For deep water, all results followed those previously reported for fully submerged jets. As the depth decreases (or dF=H increases) to the surface contact regime, dilutions begin to decrease. Tracer concentration profiles are truncated at the water surface and in shallow water resemble half-Gaussian profiles similar to those of wall jets. The jets can cling to the water surface, although the locations of the bottom impact point and near-field length are not significantly affected by the water surface. In deep water and surface contact regimes, the impact point and near-field dilutions are highest for 60° nozzles. As the depth decreases further, however, the dilutions for the three nozzle angles become approximately equal, until, for shallow water, the 30°-nozzle gives slightly higher dilution. The 30°-nozzle may be preferable for this case because there is less surface interaction and, therefore, less visual impact on the water surface. Previous recommendations that dense jets be submerged so that the rise height to the jet’s upper boundary be less than 75% of the water depth to avoid surface effects appear to be overly conservative and the present results suggest that the rise can be as much as 90% of the water depth for all angles with no deleterious effect on dilution.
Laboratory experiments on single dense jets oriented at angles from 15° to 85° to the horizontal ... more Laboratory experiments on single dense jets oriented at angles from 15° to 85° to the horizontal are reported. The major flow properties were measured by laser-induced fluorescence at the maximum rise height, impact point, and, for the first time, at the end of the near field. The impact point dilution was insensitive to nozzle angle over the range of about 45–65°. Because the additional mixing that occurred in the spreading layer beyond the impact point depended on nozzle angle, the near-field dilution was more sensitive to nozzle orientation and was highest for 60°, consistent with generally accepted design practice. Bottom boundary effects on dilution were also addressed. Along the jet centerline, time-average dilution first increased and then actually decreased in a thin layer up to the wall. The concentration increase near the bed is due to an increase in turbulent intermittency and accumulation of more saline fluid elements at the bed. The presence of this layer may explain wide discrepancies in reported dilutions near the boundary and may be environmentally important due to exposure of benthic organisms and sea grasses to high salinity. It may not persist, however, as it can be swept up by vortices that propagate radially away from the impact point. The vortices entrain ambient fluid leading to increased dilution, but they eventually collapse under their self-induced density stratification, marking the end of the near field.
Comprehensive laboratory experiments on multiport diffusers for dense effluents such as brine int... more Comprehensive laboratory experiments on multiport diffusers for dense effluents such as brine into stationary receiving waters are reported. Tracer concentration fields were mapped in three dimensions by laser-induced fluorescence (3DLIF). The effect of port spacing is described by s=dF where s is the port spacing, d the nozzle diameter, and F the jet densimetric Froude number. For s=dF > ∼2, the jets did not merge, and the results followed expected asymptotic solutions for single jets. For s=dF < 2 the jets merged, but did not follow expected asymptotic line source solutions. As the port spacing was reduced, the rise height and other geometrical variables decreased. The dilutions also decreased, but much more rapidly than predicted. These were caused by Coanda effects and merging. The Coanda effect caused an under pressure on the interior jet surfaces which caused them to curve more sharply inwards. This shortened their trajectories, reducing the external surface area available for entrainment. Jet merging restricted entrainment of clear water to the inner surfaces and exacerbated the Coanda effect. The implications for numerical modeling are discussed. Integral entrainment models that assume unrestricted entrainment water, neglect reentrainment, and neglect dynamic interaction (Coanda effect) between jets may significantly overestimate dilution. Insight into port spacing effects can be obtained from studies on positively buoyant jets. To prevent reduction in dilution attributable to restricted entrainment, it is recommended to maintain adequate port spacing so that s=dF > ∼2.
Abstract Direct discharges of municipal and industrial waste waters into water bodies through mar... more Abstract Direct discharges of municipal and industrial waste waters into water bodies through marine outfalls are considered as a common way to dispose the generated waste in coastal zones. Marine discharge, intensifying flow mixing and entrainment, decrease the concentration of polutant up to accepted concentration and meet the guideline values and to make possible continues discharge of flow into matine environment.
Abstract In this paper, a simple methodology based on multivariate analysis is developed to creat... more Abstract In this paper, a simple methodology based on multivariate analysis is developed to create a groundwater quality index (GWQI). The methodology is based on three general stages, selection, standardization and aggregation, to develop a groundwater quality index in an area using regional and local standards.
A series of laboratory experiments have been conducted for negatively buoyant effluents discharge... more A series of laboratory experiments have been conducted for negatively buoyant effluents discharged through a protruding surface channel into unstratified stagnant water. The mixing behavior of the flow has been analyzed using digital video recordings of the dye colored discharge together with micro conductivity probe measurements. Plume trajectories and geometries have been determined by image processing and dilutions from the conductivity probe data. Comparison of non-dimensional results for plume characteristics showed similar features to those of submerged positively buoyant jets. However, notable differences are observed in the flow behavior prior to it plunging away from the free surface. As expected the overall dilution is lower when compared to submerged discharges. These differences are quantified and the new results provide information that can be used for the preliminary design of dense surface discharges.
Surface discharges of negatively buoyant jets into moving ambient water create a range of complex... more Surface discharges of negatively buoyant jets into moving ambient water create a range of complex flow patterns. These complexities arise through the interplay between the discharge's initial fluxes and the motion of the ambient current. In this study a series of laboratory experiments were conducted for negatively buoyant surface discharges into crossflow to investigate flow patterns under different discharge and ambient conditions. The results compared with simulations of the CORMIX model, an expert system for ocean outfall design. In CORMIX, the simulation module DHYDRO for dense discharges has been used. Finally the flow different patterns were arranged in a dimensionless diagram to propose a modified flow classification system with new criteria.
Surface discharges of negatively buoyant jets into moving ambient water create a range of complex... more Surface discharges of negatively buoyant jets into moving ambient water create a range of complex flow patterns.These complexities arise through the interplay between the discharge’s initial fluxes and the motion of the ambient current. In this study a series of laboratory experiments were conducted for negatively buoyant surface discharges into crossflow to investigate flow patterns under different discharge and ambient conditions. The results compared with simulations of the CORMIX model, an expert system for ocean outfall design. In CORMIX, the simulation module DHYDRO for dense discharges has been used. Finally the flow different patterns were arranged in a dimensionless diagram to propose a modified flowclassification system with new criteria
Ports’ activities could result in oil spills occurrences and oil pollution in different ways incl... more Ports’ activities could result in oil spills occurrences and oil pollution in different ways including the discharges of ships’ oily wastes, discharges of oily ballast water and leaks at oil terminals. In this paper, using the results of the analyses of the hydrocarbon compounds in the samples collected from the sediments in the Anzali Port in the Caspian Sea in Iran, the levels of oil pollution in the sediments, in terms of Total Petroleum Hydrocarbons and Petroleum Aromatic Hydrocarbons, are studied. Also using a number of existing biomarker profiles, the sources of aliphatic hydrocarbons were investigated. The concentration of Total Petroleum Hydrocarbons ranged between 7.6 to 29 mg/kg indicated that oil pollution content of the sediments in the area is at a low to medium level. Also the concentrations of PAHs in the sediments were very low (0.62 – 6.12 ng/g). This indicated that the sediments sampled in the study area can be considered unpolluted in terms of aromatic hydrocarbons. Analyses of the samples using a number of biomarkers showed a combination of natural (marine and terrestrial) and petrogenic hydrocarbons in the sediments in the Anzali Port area.
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Papers by ozeair Abessi
a high-dimensional state space. We also explain the relation between Taylor’s hypothesis and the comoving frame velocity Ud of the turbulent orbit in state space. In particular, in physical space we observe flow structures that deform as they advect downstream at a speed that differs significantly from Ud. Indeed, the symmetry-reduction analysis of planar dye concentration fields at Reynolds number Re = 3200 reveals that the speed u at which high-concentration peaks advect is
roughly 1.43 times Ud. In a physically meaningful symmetry-reduced frame, the excess speed u-Ud = 0.43 Ud can be explained in terms of the so-called geometric
phase velocity Ug associated with the orbit in state space. The ‘self-propulsion velocity’ Ug is induced by the shape-changing dynamics of passive scalar structures observed in the symmetry-reduced frame, in analogy with that of a swimmer at flow Reynolds numbers.
were conducted with nozzles oriented at 30°, 45°, and 60° to the horizontal and the spatial variations of tracer concentrations were measured by three-dimensional laser-induced fluorescence (3DLIF). Three flow regimes were identified: deep water, surface contact, and shallow water. The regimes depend on the value of dF=H, where d is the nozzle diameter, F the jet densimetric Froude number, and H the water depth; criteria were presented for the transitions between them. Flow images revealed complex three-dimensional interactions with the free surface, especially for steep nozzle angles in shallow water. Dilutions at critical points and their locations were measured. For deep water, all
results followed those previously reported for fully submerged jets. As the depth decreases (or dF=H increases) to the surface contact regime, dilutions begin to decrease. Tracer concentration profiles are truncated at the water surface and in shallow water resemble half-Gaussian profiles similar to those of wall jets. The jets can cling to the water surface, although the locations of the bottom impact point and near-field
length are not significantly affected by the water surface. In deep water and surface contact regimes, the impact point and near-field dilutions
are highest for 60° nozzles. As the depth decreases further, however, the dilutions for the three nozzle angles become approximately equal, until, for shallow water, the 30°-nozzle gives slightly higher dilution. The 30°-nozzle may be preferable for this case because there is less
surface interaction and, therefore, less visual impact on the water surface. Previous recommendations that dense jets be submerged so that the rise height to the jet’s upper boundary be less than 75% of the water depth to avoid surface effects appear to be overly conservative and the present results suggest that the rise can be as much as 90% of the water depth for all angles with no deleterious effect on dilution.
properties were measured by laser-induced fluorescence at the maximum rise height, impact point, and, for the first time, at the end of the near
field. The impact point dilution was insensitive to nozzle angle over the range of about 45–65°. Because the additional mixing that occurred in
the spreading layer beyond the impact point depended on nozzle angle, the near-field dilution was more sensitive to nozzle orientation and was highest for 60°, consistent with generally accepted design practice. Bottom boundary effects on dilution were also addressed. Along the jet centerline, time-average dilution first increased and then actually decreased in a thin layer up to the wall. The concentration increase near
the bed is due to an increase in turbulent intermittency and accumulation of more saline fluid elements at the bed. The presence of this layer may explain wide discrepancies in reported dilutions near the boundary and may be environmentally important due to exposure of benthic
organisms and sea grasses to high salinity. It may not persist, however, as it can be swept up by vortices that propagate radially away from the impact point. The vortices entrain ambient fluid leading to increased dilution, but they eventually collapse under their self-induced density stratification, marking the end of the near field.
results compared with simulations of the CORMIX model, an expert system for ocean outfall design. In CORMIX, the simulation module DHYDRO for dense discharges has been used. Finally the flow different patterns were arranged in a dimensionless diagram to propose a modified flowclassification system with new criteria
a high-dimensional state space. We also explain the relation between Taylor’s hypothesis and the comoving frame velocity Ud of the turbulent orbit in state space. In particular, in physical space we observe flow structures that deform as they advect downstream at a speed that differs significantly from Ud. Indeed, the symmetry-reduction analysis of planar dye concentration fields at Reynolds number Re = 3200 reveals that the speed u at which high-concentration peaks advect is
roughly 1.43 times Ud. In a physically meaningful symmetry-reduced frame, the excess speed u-Ud = 0.43 Ud can be explained in terms of the so-called geometric
phase velocity Ug associated with the orbit in state space. The ‘self-propulsion velocity’ Ug is induced by the shape-changing dynamics of passive scalar structures observed in the symmetry-reduced frame, in analogy with that of a swimmer at flow Reynolds numbers.
were conducted with nozzles oriented at 30°, 45°, and 60° to the horizontal and the spatial variations of tracer concentrations were measured by three-dimensional laser-induced fluorescence (3DLIF). Three flow regimes were identified: deep water, surface contact, and shallow water. The regimes depend on the value of dF=H, where d is the nozzle diameter, F the jet densimetric Froude number, and H the water depth; criteria were presented for the transitions between them. Flow images revealed complex three-dimensional interactions with the free surface, especially for steep nozzle angles in shallow water. Dilutions at critical points and their locations were measured. For deep water, all
results followed those previously reported for fully submerged jets. As the depth decreases (or dF=H increases) to the surface contact regime, dilutions begin to decrease. Tracer concentration profiles are truncated at the water surface and in shallow water resemble half-Gaussian profiles similar to those of wall jets. The jets can cling to the water surface, although the locations of the bottom impact point and near-field
length are not significantly affected by the water surface. In deep water and surface contact regimes, the impact point and near-field dilutions
are highest for 60° nozzles. As the depth decreases further, however, the dilutions for the three nozzle angles become approximately equal, until, for shallow water, the 30°-nozzle gives slightly higher dilution. The 30°-nozzle may be preferable for this case because there is less
surface interaction and, therefore, less visual impact on the water surface. Previous recommendations that dense jets be submerged so that the rise height to the jet’s upper boundary be less than 75% of the water depth to avoid surface effects appear to be overly conservative and the present results suggest that the rise can be as much as 90% of the water depth for all angles with no deleterious effect on dilution.
properties were measured by laser-induced fluorescence at the maximum rise height, impact point, and, for the first time, at the end of the near
field. The impact point dilution was insensitive to nozzle angle over the range of about 45–65°. Because the additional mixing that occurred in
the spreading layer beyond the impact point depended on nozzle angle, the near-field dilution was more sensitive to nozzle orientation and was highest for 60°, consistent with generally accepted design practice. Bottom boundary effects on dilution were also addressed. Along the jet centerline, time-average dilution first increased and then actually decreased in a thin layer up to the wall. The concentration increase near
the bed is due to an increase in turbulent intermittency and accumulation of more saline fluid elements at the bed. The presence of this layer may explain wide discrepancies in reported dilutions near the boundary and may be environmentally important due to exposure of benthic
organisms and sea grasses to high salinity. It may not persist, however, as it can be swept up by vortices that propagate radially away from the impact point. The vortices entrain ambient fluid leading to increased dilution, but they eventually collapse under their self-induced density stratification, marking the end of the near field.
results compared with simulations of the CORMIX model, an expert system for ocean outfall design. In CORMIX, the simulation module DHYDRO for dense discharges has been used. Finally the flow different patterns were arranged in a dimensionless diagram to propose a modified flowclassification system with new criteria