Papers by Farhad Bahmanpouri
Investigating the sidewall's effects on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:mrow><mml:mi>π</mml:mi></mml:mrow></mml:math>-shaped floating breakwaters interacting with water waves by the scaled boundary FEM
Ocean Engineering, Sep 1, 2023
Presenting the hydraulic complexity parameters M1, M2 and M3, case study Po River, Italy
Proceedings of the 39th IAHR World Congress, 2022
Numerical study of flow characteristics and energy dissipation over the slotted roller bucket system
Modeling Earth Systems and Environment, Apr 16, 2022
The present study aims to evaluate the effects of the arrangement of the teeth in terms of angle,... more The present study aims to evaluate the effects of the arrangement of the teeth in terms of angle, arrangement and radius on the eddy currents, kinetic energy dissipation and turbulence dissipation rate. Four groups of models were created for this purpose. In the first group, each model contained a bucket with two teeth with different angles. The second group included three models where each bucket had two teeth with the same angle, but the angle was different for each bucket. The third group contained three models with different bucket radii. In addition, the last group consisted of two models where each model had two teeth with an angle of 45°. The result showed that the use of teeth with unequal angles plays a significant role in increasing the total turbulence loss. Moreover, the angle of the teeth has a much larger effect on increasing the turbulence loss than changing the bucket radius. In addition, the use of unequal angles in the design of the teeth can significantly increase the loss. The loss can be significantly increased if a larger radius and unequal tooth angles are used simultaneously. Using equal tooth angles with a larger angle result in more loss compared to the case where the angles are small but different. Finally, buckets with larger radius and unaligned and larger tooth angles are considered as the factors that increase the energy loss in buckets, which leads to an increase in the efficiency of the bucket.
Air–water flow properties in hydraulic jumps on rough pebbled bed
ISH Journal of Hydraulic Engineering, May 1, 2022
8th IAHR World Congress - "Water: Connecting the World", Sep 1, 2019
The hydraulic jump is a sudden transition from a supercritical flow to a subcritical motion, char... more The hydraulic jump is a sudden transition from a supercritical flow to a subcritical motion, characterised by strong turbulence, air entrainment and energy dissipation. A hydraulic jump results in strong interactions between turbulence, free-surface and air-water mixing. Past research on hydraulic jump with bed roughness focused on the identification of basic parameters including conjugate depth ratio, roller length and mean velocity. However, to date, only very few studies have addressed the air-water flow parameters. This paper aims to investigate the basic parameters of air-water flow in hydraulic jump on pebbled rough bed. The experiments were performed in a channel with partially-developed inflow conditions. The gravel materials, mixed natural river pebbles, were installed on the bed for the whole length of the flume. A phase-detection double-tip conductivity probe was used to measure the basic air-flow properties. The experiments were conducted for discharges ranging from 0.06 to 0.1 m 3 /s, corresponding to inflow Froude numbers Fr1 between 1.7 and 2.84 and Reynolds number Re1 from 170,000 to 220,000. Comparisons between rough and smooth bed data, as well as with the literature highlighted some distinctive effects of the non-uniform bed roughness. The results on rough pebble bed showed a shorter roller length and higher magnitudes of air-flow properties including void fraction and bubble count rate than those on smooth bed, especially in the region close to the jump toe.
Shannon and Tsallis entropy results for particle resting times and jump lengths in river bedload&#160
Estimating the hydrodynamic and morphodynamic characteristics using Entropy theory at the confluence of Negro and Solimões Rivers
&amp;lt;p&amp;gt;When two mega rivers merge the mixing of two flows results in a highly c... more &amp;lt;p&amp;gt;When two mega rivers merge the mixing of two flows results in a highly complex three-dimensional flow structure in an area known as the confluence hydrodynamic zone. In the confluence zone, substantial changes occur to the hydrodynamic and morphodynamic features which are of significant interest for researchers. The con&amp;amp;#64258;uence of the Negro and Solim&amp;amp;#245;es Rivers, as one of the largest river junctions on Earth, is the study area of the present research. During the EU-funded Project &amp;amp;#8220;Clim-Amazon&amp;amp;#8221; (2011-2015), velocity data were collected using an ADCP vessel operating under high and low flow conditions in different locations at that confluence (Gualtieri et al., 2019). By applying the Entropy theory developed by Chiu (1988) for natural channels and simplified by Moramarco et al. (2014), the two-dimensional velocity distribution, as well as depth-averaged velocity, were calculated at the different transects along the confluence zone, using only the surface velocities observation. The estimated data yielded 6.6% and 6.9% error percentage for the discharge data related to high and low flow conditions, respectively, and 8.4% and 8.3% error percentage for the velocity data related to high and low flow conditions, respectively. Regardless of the flow condition, these preliminary results also suggest the potential points at the confluence zone for the maximum local scouring. The findings of the current research highlighted the potential of Entropy theory to estimate the flow characteristics at the large river&amp;amp;#8217;s confluence, just starting from the measure of surface velocities. This is of considerable interest for monitoring high flows using&amp;amp;#160;no-contact technology, when ADCP or other contact equipment cannot be used for the safety of operators and risks for equipment loss.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Keywords: Amazon River, Negro/Solim&amp;amp;#245;es Confluence, Entropy Theory, Velocity Distribution, Local Scouring&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;References&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Gualtieri, C., Ianniruberto, M., Filizola, N. (2019). On the mixing of rivers with a difference in density: the case of the Negro/Solim&amp;amp;#245;es confluence, Brazil. Journal of Hydrology, 578(11), November 2019, 124029,&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Chiu, C. L. (1988). &amp;amp;#8220;Entropy and 2-D velocity distribution in open channels&amp;amp;#8221;. Journal of Hydrologic Engineering, ASCE, 114(7), 738-756&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Moramarco, T., Saltalippi, C., Singh, V.P. (2004). &amp;amp;#8220;Estimation of mean velocity in natural channels based on Chiu&amp;amp;#8217;s velocity distribution equation&amp;amp;#8221;. Journal of Hydrologic Engineering, ASCE, 9 (1), pp. 42-50&amp;lt;/p&amp;gt;
The regionalizing of the entropy parameter over the north Algerian watersheds: a discharge measurement approach for ungauged river sites
Hydrological Sciences Journal-journal Des Sciences Hydrologiques, Aug 5, 2022
Dam-break flow dynamics over a stepped channel with vegetation
Journal of Hydrology, Oct 1, 2022
Journal of Hydrology, Mar 1, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Estimating the Average River Cross‐Section Velocity by Observing Only One Surface Velocity Value and Calibrating the Entropic Parameter
Water Resources Research, Oct 1, 2022
The current research aims to predict the velocity distribution and discharge rates in rivers base... more The current research aims to predict the velocity distribution and discharge rates in rivers based on the entropy concept using only one surface velocity measurement. In this direction, first, the uncrewed aerial vehicle (UAV)‐based image acquisition technique was applied to collect the surface velocity distribution along two European rivers, the Sajó, and the Freiberger Mulde Rivers. Seven cross sections were chosen for the analysis. At each cross section, first, the entropic parameter Φ(M) was calibrated based on the maximum and mean velocity magnitudes, derived from Acoustic Doppler Current Profilers, respectively, showing a trend for all cross sections with a range of 0.6 &lt; Φ(M) &lt; 0.75. Next, the maximum surface velocity provided by the UAV was implemented as a single velocity input. Finally, the bathymetry data, herein collected by UAV, were considered as the input for the entropy approach. In this way, the entropy iterative method allowed estimating the mean flow velocity by identifying the location (dip) of maximum velocities across the river site and inferring the 2D velocity distribution. The results highlighted that the entropy approach can accurately predict the velocity distribution and discharge rates with a percentage error lower than 13%.
Numerical Study of the Dynamics and Structure of a Partial Dam-Break Flow Using the VOF Method
Water Resources Management, Mar 1, 2021
This paper aims to evaluate the effects of the opening width of a dam site on the evolution of pa... more This paper aims to evaluate the effects of the opening width of a dam site on the evolution of partial dam-break waves over a fixed dry bed. The volume of fluid (VOF) method was used to scrutinize the propagation of the dam-break free surface. The model was validated using experimental data provided in the literature. At the same time, a sensitivity analysis was conducted on the size of the mesh cells and the turbulence model. However, the large eddy simulation (LES) method showed the highest accuracy among all the models. The results affirmed the crucial role of the opening width of the dam site in the flow characteristics. In this direction, diminishing the opening width results in a reduction of the wave-front travel distance, free surface gradient within the reservoir, outflow discharge values, damping the outflow hydrographs and decreasing the Froude number values at the dam site. Conversely, this leads to an increase in the air bubbles entrained within the wave and results in energy dissipation across the downstream channel.
Geosciences, May 3, 2018
Confluences are a common feature of riverine systems; the area of converging flow streamlines and... more Confluences are a common feature of riverine systems; the area of converging flow streamlines and potential mixing of separate flows. The hydrodynamics about confluences have a highly complex three-dimensional flow structure. This paper presents the results of a numerical study using the CCHE2D code to investigate the influence of junction angle and discharge ratio on the flow and erosion patterns. The hydraulic and geometric parameters which affect the maximum relative scouring depth are analyzed. The model is first calibrated and validated. Then three discharge ratios, seven junction angles and five width ratios are considered and compared. Results generally agree with experimental data and show that the process of scouring depends on all these parameters. Numerical results demonstrate that a decrease in the ratio of the tributary width to the main channel width results in an increase in the size of the separation zone. Furthermore, the increase in the width ratio leads to a decrease in the maximum depth of bed erosion. Finally, the maximum depth of bed erosion at the confluence increases with the increasing angle of the junction.
Riprap Effect on Hydraulic Fracturing Process of Cohesive and Non-cohesive Protective Levees
Water Resources Management, 2022
A comprehensive experimental study was conducted to evaluate the effects of soil properties and t... more A comprehensive experimental study was conducted to evaluate the effects of soil properties and the rip-rap as well as cohesive and non-cohesive soil material and the riprap particle size on the breaching process and the failure mechanism of the levee. The results showed the crucial role of the riprap coverage and the soil properties in the breaching of the protective levees. In this regard, breaching was developed in both vertical and transverse directions. In the levee without riprap coverage, breach development was observed in the transverse direction while the levee was eroded in the streamwise direction. In contrast, in the levee with riprap coverage, breach development mainly occurred in the vertical direction. Furthermore, the flow rate across the breach was higher in the tests with no riprap compared to those with the riprap coverage. Comparisons suggested that the shorter the failure time, the longer the equilibrium time. The present research has some major implications for coastal and hydraulic engineering designs since the construction of levees is of great importance. Furthermore, the findings can be used to predict flooding and erosion induced by the embankment failure.
Investigating the characteristic of hydraulic T-jump on rough bed based on experimental and numerical modeling
Modeling Earth Systems and Environment, Jun 27, 2022
Hydraulic jumps occur when upstream supercritical flow suddenly transitions into downstream subcr... more Hydraulic jumps occur when upstream supercritical flow suddenly transitions into downstream subcritical flows. Extremely turbulent flow of the hydraulic jump associated with the development of large-scale turbulence, surface waves and spray, air entrainment and energy dissipation. Hydraulic jumps are commonly taking place in natural waterways and hydraulic structures. Enhancement of energy dissipation, fluid mixing or flow re-aeration are the usage
Investigating the sidewall's effects on π-shaped floating breakwaters interacting with water waves by the scaled boundary FEM
Ocean Engineering
Water Science and Engineering, 2023
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Water Science and Engineering, 2023
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Hydrology Research
Hydraulic complexity metrics referred to as M1 and M2 play an important role when it comes to the... more Hydraulic complexity metrics referred to as M1 and M2 play an important role when it comes to the analysis of habitat metrics. In the present paper, the significance of these parameters is analysed by using laboratory data as well as field observations along the Tiber River in Italy. Based on the laboratory data, the estimated parameters allow us to characterise the high/low-velocity areas. Based on field observations, larger magnitudes of M1 are linked to the zones with large changes in cross-sectional flow velocity. Larger magnitudes of M2 are observed at the left bank of the channel for all flow conditions, suggesting locations with larger kinetic energy consumption for aquatic organisms. Overall, the findings of the present research would be of particular interest in quantifying biologically important flow patterns occurring at different spatial scales within different streams and flow conditions.
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Papers by Farhad Bahmanpouri