I am a Physical Oceanographer and Coastal Modeler/Engineer. Currently, I am developing coupled hydrodynamic-wave-sediment model applied to Louisiana-Texas Continental Shelf as well as estuarine shallow water systems, using FVCOM model. Supervisors: Professor Haosheng Huang
The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be use... more The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be used as the basis of a fishery port site selection study. The Tang inlet, located on the south-eastern shores of Iran, has so far been experiencing a cyclic migration with a return period of approximately a decade. In order to grasp the essence of the morphological behavior of the inlet, a two-fold site monitoring campaign was performed, consisting of a shoreline evolution study using aerial & satellite imagery for the outside of the bay as well as a sedimentation pattern comparison based on past hydrographical survey results for the inside of the bay utilizing ArcGIS software. Subsequently, numerical modeling of the inlet comprising of nearshore wave transformation, tidal regime of the bay, one-line coastline evolution and two-dimensional sediment transport within the bay was carried out utilizing MIKE 21 package. Ebb channel switching from a westerly to an easterly orientation is deemed t...
The wave characteristics and wave-current interaction in the six tidal inlets connecting the Bara... more The wave characteristics and wave-current interaction in the six tidal inlets connecting the Barataria Basin and the northern Gulf of Mexico are investigated during spring-summer time period when both cold front passage and persistent southeast wind events exist. A fully-coupled unstructured-grid, three-dimensional, FVCOM-SWAVE model is employed and validated against observational data during April-June 2010. Model simulation results indicate that waves in the shelf side of the inlets are mainly wind seas and swells from the Gulf of Mexico that are modified by ocean currents in the Louisiana Bight. These currents include Mississippi River plume, buoyancy-and wind-driven alongshore current, as well as the tidal jet in the Barataria Pass. The bay side of the inlets, similar to the interior of the Barataria Basin, is dominated by locally generated waves. In the middle of the inlets, both wind seas and swells are presented at times, though different inlets behave differently in terms of contribution from each component. The contribution of local wind seas enhances during cold front passage. Contrastingly, the influence of swells from continental shelf is more pronounced during persistent southeast wind event. FVCOM-SWAVE predicts a decrease in significant wave height inside the Louisiana Bight due to current-induced refraction and wave stretching effect caused by clockwise gyre from Mississippi plume. The modulation of significant wave height at Barataria Pass due to partial wave blocking for the opposing current, and wave stretching for the following current can be up to 20%. The effect of depth-induced breaking and bottom friction overshadows the one from wave-current interaction at other shallower inlets.
In wall-bounded time-periodic flows, nonlinearity, associated with
higher harmonic term(s) in vel... more In wall-bounded time-periodic flows, nonlinearity, associated with higher harmonic term(s) in velocity and/or acceleration outside the boundary layer, can significantly change the wall turbulence compared with that in the linear Stokes Boundary Layer. A significant feature of a nonlinear wall-bounded turbulent time-periodic flow is the formation of a net current which has not yet been mechanistically explained. This study investigates the effects of asymmetric velocity outside the boundary layer on wall turbulence and net current formation through Direct Numerical Simulations of a smooth-walled planar channel driven by the Second-order Stokes Wave. Simulation results suggest that net current characteristics depend on whether developed turbulence is present. When turbulence is developed, asymmetric viscous length scale is found to be the primary reason of the net current whereby a vertical offset between negative and positive Reynolds shear stress profiles, associated with forward and reverse flows, respectively, is created in a cycle. After averaging over a cycle, residual Reynolds shear stress, which drives the net current, is observed to be within the offset layer.
The present case study serves the two-fold objective of firstly addressing the less documented de... more The present case study serves the two-fold objective of firstly addressing the less documented design context of single layer armoured breakwaters nearby a curved step-like bathymetric feature, while secondly striving for accurate design wave boundary conditions after numerical modelling of wave transformations on a fine spatial grid near the step-like feature to account for the localized effects on the design waveheights. A detailed extremal analysis was performed on hindcast wave results verified against buoy and satellite data, investigating the goodness of fit for a large number of candidate long-term probability distributions. Numerical modelling results show an amplification of waveheights due to the combined shoaling and focusing effects of nearshore bathymetry for certain sectors of wave approach, including the direction of the highest deep-water waves, while for other directions exacerbated dispersion results in further reduction of the refracted waveheights. Preliminary hydraulic design of the breakwaters was undertaken prior to further study by physical modelling.
31st International Conference in Coastal Engineering, May 1, 2009
A new model for calculating suspended sediment concentration of cohesive sediments is presented. ... more A new model for calculating suspended sediment concentration of cohesive sediments is presented. Processes that govern the behaviour of cohesive sediments differ significantly from those governing non- cohesive sediments. In addition to the physical complexities of cohesive sediment processes, chemical and biological aspects must be considered as well. All of these factors point to the need for a multi-disciplinary approach in studies that seek a better understanding of the transport of cohesive sediment. Several new concepts were incorporated in the proposed model which is capable of estimating the space and time variation of the concentration of cohesive sediment. First, the model incorporates the effect of electrochemical forces between cohesive sediment particles. Second, the wave friction factor is expressed in terms of the median particle size diameter in order to enhance the accuracy of the estimation of bed shear stress. Third, the erosion rate of cohesive sediments is also expressed as in a time-dependent form. None of the aforementioned phenomena have been previously included in mud transport models. Simulated suspended sediment concentration profiles are compared with field data collected from Vermilion Bay, Louisiana (Kemp, 1986). Comparisons between the numerical model results and field data indicate that the model performs satisfactory.
32nd International Conference on Coastal Engineering Proceedings, Jan 31, 2011
The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be use... more The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be used as the basis of a fishery port site selection study. The Tang inlet, located on the south-eastern shores of Iran, has so far been experiencing a cyclic migration with a return period of approximately a decade. In order to grasp the essence of the morphological behavior of the inlet, a two-fold site monitoring campaign was performed, consisting of a shoreline evolution study using aerial & satellite imagery for the outside of the bay as well as a sedimentation pattern comparison based on past hydrographical survey results for the inside of the bay utilizing ArcGIS software. Subsequently, numerical modeling of the inlet comprising of nearshore wave transformation, tidal regime of the bay, one-line coastline evolution and two-dimensional sediment transport within the bay was carried out utilizing MIKE 21 package. Ebb channel switching from a westerly to an easterly orientation is deemed to occur due to self-suffocation as a result of the presence of an existing offshore rock formation, as well as the salient making potential of the rock system. On the other hand, the closure of the east-facing channel is mainly attributed to diffraction currents due to Monsoon southerly waves helped by sedimentation load from inside the bay system due to floods & ebb currents.
32nd International Conference on Coastal Engineering Proceedings, Jan 30, 2011
A series of laboratory wave-flume experiments was conducted to investigate the dissipation of mon... more A series of laboratory wave-flume experiments was conducted to investigate the dissipation of monochromatic regular waves on a horizontal muddy bed of commercial kaolinite. The rheological parameters of kaolinite samples with different water content ratios were obtained from controlled shear rate tests using the rheometer. The flow curves of shear stress versus shear rate were found to be essentially Bingham viscoplastic medium for steady unidirectional mud flows of the rheological tests. Assuming Bingham behavior for kaolinite, a wave-mud interaction model was employed to obtain the values of the wave attenuation coefficients. Comparisons between the measured and simulated results show a good agreement.
The Proceedings of the Coastal Sediments 2011, Apr 2011
This paper presents a multi-criteria analysis of potential sites intended for the construction of... more This paper presents a multi-criteria analysis of potential sites intended for the construction of a petroleum export port along the North-Western shores of the Persian Gulf, with particular attention to sediment transport considerations being necessary due to proximity of both sites to the Mond river, as the latter acts as a considerable source of alluvial sediments, greatly influencing the geomorphology of the Persian Gulf Northern shores. Although, various criteria interplay in the site-selection process for such a major port, however, the potential cost impact of future maintenance dredging on overall project costs is seen to be so large as to govern the final decision. Two potential port construction sites, as chosen at different distances away from the river mouth, namely, Chah-Pahn and Kabgan locations, are studied and compared, particularly from a future maintenance dredging costs point of view in order to arrive at the best overall alternative.
17th Canadian Hydrotechnical Engineering Conference, 2007
The current paper deals with the incorporation of the effect of electrochemical behaviour of cohe... more The current paper deals with the incorporation of the effect of electrochemical behaviour of cohesive sediments and of the wave friction factor in a numerical model in order to estimate the space and time variation of the cohesive sediment concentration. The processes that govern the behaviour of cohesive sediments differ significantly from those governing non-cohesive sediments. In addition to the physical complexities of cohesive sediment processes, chemical aspects must be considered as well. In this sense, the electrochemical behaviour of cohesive sediments plays an important role as a stabilizing force against the eroding shear force. On the other hand, cohesive sediments are important in terms of environmental impacts due to their association with contaminants. All of these factors point to the need for a multi-disciplinary approach in studies that seek a better understanding of cohesive sediment transport. Although cohesive sediment transport under current and wave action has been investigated by several researchers such as Ross and Mehta (1990), electrochemical resistance of cohesive sediments and the effect of wave friction factor have not been incorporated in previous models. The proposed model includes both of these phenomena. Simulated suspended sediment concentration profiles are compared with experimental data from Vermilion Bay, Louisiana. The comparisons indicate that the model performs satisfactorily, especially at the end of the simulation time when equilibrium has been achieved.
The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be use... more The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be used as the basis of a fishery port site selection study. The Tang inlet, located on the south-eastern shores of Iran, has so far been experiencing a cyclic migration with a return period of approximately a decade. In order to grasp the essence of the morphological behavior of the inlet, a two-fold site monitoring campaign was performed, consisting of a shoreline evolution study using aerial & satellite imagery for the outside of the bay as well as a sedimentation pattern comparison based on past hydrographical survey results for the inside of the bay utilizing ArcGIS software. Subsequently, numerical modeling of the inlet comprising of nearshore wave transformation, tidal regime of the bay, one-line coastline evolution and two-dimensional sediment transport within the bay was carried out utilizing MIKE 21 package. Ebb channel switching from a westerly to an easterly orientation is deemed t...
The wave characteristics and wave-current interaction in the six tidal inlets connecting the Bara... more The wave characteristics and wave-current interaction in the six tidal inlets connecting the Barataria Basin and the northern Gulf of Mexico are investigated during spring-summer time period when both cold front passage and persistent southeast wind events exist. A fully-coupled unstructured-grid, three-dimensional, FVCOM-SWAVE model is employed and validated against observational data during April-June 2010. Model simulation results indicate that waves in the shelf side of the inlets are mainly wind seas and swells from the Gulf of Mexico that are modified by ocean currents in the Louisiana Bight. These currents include Mississippi River plume, buoyancy-and wind-driven alongshore current, as well as the tidal jet in the Barataria Pass. The bay side of the inlets, similar to the interior of the Barataria Basin, is dominated by locally generated waves. In the middle of the inlets, both wind seas and swells are presented at times, though different inlets behave differently in terms of contribution from each component. The contribution of local wind seas enhances during cold front passage. Contrastingly, the influence of swells from continental shelf is more pronounced during persistent southeast wind event. FVCOM-SWAVE predicts a decrease in significant wave height inside the Louisiana Bight due to current-induced refraction and wave stretching effect caused by clockwise gyre from Mississippi plume. The modulation of significant wave height at Barataria Pass due to partial wave blocking for the opposing current, and wave stretching for the following current can be up to 20%. The effect of depth-induced breaking and bottom friction overshadows the one from wave-current interaction at other shallower inlets.
In wall-bounded time-periodic flows, nonlinearity, associated with
higher harmonic term(s) in vel... more In wall-bounded time-periodic flows, nonlinearity, associated with higher harmonic term(s) in velocity and/or acceleration outside the boundary layer, can significantly change the wall turbulence compared with that in the linear Stokes Boundary Layer. A significant feature of a nonlinear wall-bounded turbulent time-periodic flow is the formation of a net current which has not yet been mechanistically explained. This study investigates the effects of asymmetric velocity outside the boundary layer on wall turbulence and net current formation through Direct Numerical Simulations of a smooth-walled planar channel driven by the Second-order Stokes Wave. Simulation results suggest that net current characteristics depend on whether developed turbulence is present. When turbulence is developed, asymmetric viscous length scale is found to be the primary reason of the net current whereby a vertical offset between negative and positive Reynolds shear stress profiles, associated with forward and reverse flows, respectively, is created in a cycle. After averaging over a cycle, residual Reynolds shear stress, which drives the net current, is observed to be within the offset layer.
The present case study serves the two-fold objective of firstly addressing the less documented de... more The present case study serves the two-fold objective of firstly addressing the less documented design context of single layer armoured breakwaters nearby a curved step-like bathymetric feature, while secondly striving for accurate design wave boundary conditions after numerical modelling of wave transformations on a fine spatial grid near the step-like feature to account for the localized effects on the design waveheights. A detailed extremal analysis was performed on hindcast wave results verified against buoy and satellite data, investigating the goodness of fit for a large number of candidate long-term probability distributions. Numerical modelling results show an amplification of waveheights due to the combined shoaling and focusing effects of nearshore bathymetry for certain sectors of wave approach, including the direction of the highest deep-water waves, while for other directions exacerbated dispersion results in further reduction of the refracted waveheights. Preliminary hydraulic design of the breakwaters was undertaken prior to further study by physical modelling.
31st International Conference in Coastal Engineering, May 1, 2009
A new model for calculating suspended sediment concentration of cohesive sediments is presented. ... more A new model for calculating suspended sediment concentration of cohesive sediments is presented. Processes that govern the behaviour of cohesive sediments differ significantly from those governing non- cohesive sediments. In addition to the physical complexities of cohesive sediment processes, chemical and biological aspects must be considered as well. All of these factors point to the need for a multi-disciplinary approach in studies that seek a better understanding of the transport of cohesive sediment. Several new concepts were incorporated in the proposed model which is capable of estimating the space and time variation of the concentration of cohesive sediment. First, the model incorporates the effect of electrochemical forces between cohesive sediment particles. Second, the wave friction factor is expressed in terms of the median particle size diameter in order to enhance the accuracy of the estimation of bed shear stress. Third, the erosion rate of cohesive sediments is also expressed as in a time-dependent form. None of the aforementioned phenomena have been previously included in mud transport models. Simulated suspended sediment concentration profiles are compared with field data collected from Vermilion Bay, Louisiana (Kemp, 1986). Comparisons between the numerical model results and field data indicate that the model performs satisfactory.
32nd International Conference on Coastal Engineering Proceedings, Jan 31, 2011
The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be use... more The present paper tackles morphological modeling of a rare case of a re-migrating inlet to be used as the basis of a fishery port site selection study. The Tang inlet, located on the south-eastern shores of Iran, has so far been experiencing a cyclic migration with a return period of approximately a decade. In order to grasp the essence of the morphological behavior of the inlet, a two-fold site monitoring campaign was performed, consisting of a shoreline evolution study using aerial & satellite imagery for the outside of the bay as well as a sedimentation pattern comparison based on past hydrographical survey results for the inside of the bay utilizing ArcGIS software. Subsequently, numerical modeling of the inlet comprising of nearshore wave transformation, tidal regime of the bay, one-line coastline evolution and two-dimensional sediment transport within the bay was carried out utilizing MIKE 21 package. Ebb channel switching from a westerly to an easterly orientation is deemed to occur due to self-suffocation as a result of the presence of an existing offshore rock formation, as well as the salient making potential of the rock system. On the other hand, the closure of the east-facing channel is mainly attributed to diffraction currents due to Monsoon southerly waves helped by sedimentation load from inside the bay system due to floods & ebb currents.
32nd International Conference on Coastal Engineering Proceedings, Jan 30, 2011
A series of laboratory wave-flume experiments was conducted to investigate the dissipation of mon... more A series of laboratory wave-flume experiments was conducted to investigate the dissipation of monochromatic regular waves on a horizontal muddy bed of commercial kaolinite. The rheological parameters of kaolinite samples with different water content ratios were obtained from controlled shear rate tests using the rheometer. The flow curves of shear stress versus shear rate were found to be essentially Bingham viscoplastic medium for steady unidirectional mud flows of the rheological tests. Assuming Bingham behavior for kaolinite, a wave-mud interaction model was employed to obtain the values of the wave attenuation coefficients. Comparisons between the measured and simulated results show a good agreement.
The Proceedings of the Coastal Sediments 2011, Apr 2011
This paper presents a multi-criteria analysis of potential sites intended for the construction of... more This paper presents a multi-criteria analysis of potential sites intended for the construction of a petroleum export port along the North-Western shores of the Persian Gulf, with particular attention to sediment transport considerations being necessary due to proximity of both sites to the Mond river, as the latter acts as a considerable source of alluvial sediments, greatly influencing the geomorphology of the Persian Gulf Northern shores. Although, various criteria interplay in the site-selection process for such a major port, however, the potential cost impact of future maintenance dredging on overall project costs is seen to be so large as to govern the final decision. Two potential port construction sites, as chosen at different distances away from the river mouth, namely, Chah-Pahn and Kabgan locations, are studied and compared, particularly from a future maintenance dredging costs point of view in order to arrive at the best overall alternative.
17th Canadian Hydrotechnical Engineering Conference, 2007
The current paper deals with the incorporation of the effect of electrochemical behaviour of cohe... more The current paper deals with the incorporation of the effect of electrochemical behaviour of cohesive sediments and of the wave friction factor in a numerical model in order to estimate the space and time variation of the cohesive sediment concentration. The processes that govern the behaviour of cohesive sediments differ significantly from those governing non-cohesive sediments. In addition to the physical complexities of cohesive sediment processes, chemical aspects must be considered as well. In this sense, the electrochemical behaviour of cohesive sediments plays an important role as a stabilizing force against the eroding shear force. On the other hand, cohesive sediments are important in terms of environmental impacts due to their association with contaminants. All of these factors point to the need for a multi-disciplinary approach in studies that seek a better understanding of cohesive sediment transport. Although cohesive sediment transport under current and wave action has been investigated by several researchers such as Ross and Mehta (1990), electrochemical resistance of cohesive sediments and the effect of wave friction factor have not been incorporated in previous models. The proposed model includes both of these phenomena. Simulated suspended sediment concentration profiles are compared with experimental data from Vermilion Bay, Louisiana. The comparisons indicate that the model performs satisfactorily, especially at the end of the simulation time when equilibrium has been achieved.
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higher harmonic term(s) in velocity and/or acceleration outside the
boundary layer, can significantly change the wall turbulence compared with that in the linear Stokes Boundary Layer. A significant
feature of a nonlinear wall-bounded turbulent time-periodic flow is
the formation of a net current which has not yet been mechanistically
explained. This study investigates the effects of asymmetric velocity outside the boundary layer on wall turbulence and net current
formation through Direct Numerical Simulations of a smooth-walled
planar channel driven by the Second-order Stokes Wave. Simulation
results suggest that net current characteristics depend on whether
developed turbulence is present. When turbulence is developed,
asymmetric viscous length scale is found to be the primary reason
of the net current whereby a vertical offset between negative and
positive Reynolds shear stress profiles, associated with forward and
reverse flows, respectively, is created in a cycle. After averaging over
a cycle, residual Reynolds shear stress, which drives the net current,
is observed to be within the offset layer.
cohesive sediments. In addition to the physical complexities of cohesive sediment processes, chemical and biological aspects must be considered as well. All of these factors point to the need for a multi-disciplinary approach in studies that seek a better understanding of the transport of cohesive sediment. Several new concepts were incorporated in the proposed model which is capable of estimating the space and time variation of the concentration of cohesive sediment. First, the model incorporates the effect of electrochemical forces between cohesive sediment particles. Second, the wave friction factor is expressed in terms of the median particle size diameter in order to enhance the accuracy of the estimation of bed shear stress. Third, the erosion rate of cohesive sediments is also expressed as in a time-dependent form. None of the aforementioned phenomena have been previously included in mud transport models. Simulated suspended sediment concentration profiles are compared with field data collected from Vermilion Bay, Louisiana (Kemp, 1986). Comparisons between the numerical model results and field data indicate that the model performs satisfactory.
to the Mond river, as the latter acts as a considerable source of alluvial sediments, greatly influencing the geomorphology of the Persian Gulf Northern shores. Although, various criteria
interplay in the site-selection process for such a major port, however, the potential cost impact of future maintenance dredging on overall project costs is seen to be so large as to govern the final decision. Two potential port construction sites, as chosen at different distances away from the river mouth, namely, Chah-Pahn and Kabgan locations, are studied and compared, particularly from a future maintenance dredging costs point of view in order to arrive at the best overall alternative.
higher harmonic term(s) in velocity and/or acceleration outside the
boundary layer, can significantly change the wall turbulence compared with that in the linear Stokes Boundary Layer. A significant
feature of a nonlinear wall-bounded turbulent time-periodic flow is
the formation of a net current which has not yet been mechanistically
explained. This study investigates the effects of asymmetric velocity outside the boundary layer on wall turbulence and net current
formation through Direct Numerical Simulations of a smooth-walled
planar channel driven by the Second-order Stokes Wave. Simulation
results suggest that net current characteristics depend on whether
developed turbulence is present. When turbulence is developed,
asymmetric viscous length scale is found to be the primary reason
of the net current whereby a vertical offset between negative and
positive Reynolds shear stress profiles, associated with forward and
reverse flows, respectively, is created in a cycle. After averaging over
a cycle, residual Reynolds shear stress, which drives the net current,
is observed to be within the offset layer.
cohesive sediments. In addition to the physical complexities of cohesive sediment processes, chemical and biological aspects must be considered as well. All of these factors point to the need for a multi-disciplinary approach in studies that seek a better understanding of the transport of cohesive sediment. Several new concepts were incorporated in the proposed model which is capable of estimating the space and time variation of the concentration of cohesive sediment. First, the model incorporates the effect of electrochemical forces between cohesive sediment particles. Second, the wave friction factor is expressed in terms of the median particle size diameter in order to enhance the accuracy of the estimation of bed shear stress. Third, the erosion rate of cohesive sediments is also expressed as in a time-dependent form. None of the aforementioned phenomena have been previously included in mud transport models. Simulated suspended sediment concentration profiles are compared with field data collected from Vermilion Bay, Louisiana (Kemp, 1986). Comparisons between the numerical model results and field data indicate that the model performs satisfactory.
to the Mond river, as the latter acts as a considerable source of alluvial sediments, greatly influencing the geomorphology of the Persian Gulf Northern shores. Although, various criteria
interplay in the site-selection process for such a major port, however, the potential cost impact of future maintenance dredging on overall project costs is seen to be so large as to govern the final decision. Two potential port construction sites, as chosen at different distances away from the river mouth, namely, Chah-Pahn and Kabgan locations, are studied and compared, particularly from a future maintenance dredging costs point of view in order to arrive at the best overall alternative.