safa ibrahim - Academia.edu (original) (raw)

Papers by safa ibrahim

Engineering, Technology & Applied Science Research

The current study examines the numerical analysis of the laminar flow around a cylinder at variou... more The current study examines the numerical analysis of the laminar flow around a cylinder at various Reynolds numbers (0.1, 1.1, 20, 26, 50, 100, and 195). The research found that a steady state can exist for Reynolds number values of 0.1, 1.1, 20, and 26. However, the flow pattern becomes unstable at Reynolds numbers 50, 100, and 195, leading to the development of the Kármán vortex street. The FEATool Multiphysics software in MATLAB (R2019b) was utilized to numerically solve the steady 2D Navier-Stokes equation. The study compared the estimated drag coefficient to previous experimental and analytical studies in Abaqus/CFD. The lift and pressure coefficients were also calculated, and their results were found to be in strong agreement with earlier investigations in terms of predicting pressure and velocity distribution. The analysis provided insight into how the flow field changes with increasing Reynolds numbers.

Arabian Journal for Science and Engineering, 2016

The aim of the present investigation is to study the effect of both side and bed slopes on the fl... more The aim of the present investigation is to study the effect of both side and bed slopes on the flow over free overfalls in trapezoidal channels, three models of trapezoidal free overfall channels have been built and tested in a laboratory flume. These models had 0.1 m bed width and 3.7 m length with different values of side slope (m = 0.268, 0.577, and 1). Each model had four different bed slopes (S = 0, 0.0033, 0.01, and 0.02). A total of twelve series of the experiments were tested for different ranges of Froude number. Experimental results of all models showed that the variation of (Qm 1.5 / gb 5) with (my b /b) for different values of side slope and different bed slopes is a simple power equation. It was observed that the values of (Qm 1.5 / gb 5) increase with the increase in (my b /b) values. The correlation between (my b /b) with (my c /b) is found to be linear for different bed slopes. The ratio (y b /y c) decreases with the increase of slope (S) with an average value of 0.729 for subcritical and supercritical flow on smooth beds of different slopes. An empirical expression is obtained for the variation of (Qm 1.5 / gb 5) with (my b /b), and (S). The results of the present study have been compared with theoretical and experimental results obtained by other investigators showing well agreements.

Revista de Chimie

Prediction of the flow pattern is a central problms in multi-phase flow analysis. It is a vital p... more Prediction of the flow pattern is a central problms in multi-phase flow analysis. It is a vital point for researchers to accurately predict which flow pattern category types will occur at different flow rates. For this purpose, a mathematical model using the MATLAB (R2017b) computer program is developed for the prediction of gas-liquid two-phase flow patterns in a horizontal pipe with an inner diameter of 30mm under standard conditions. The properties of the air-water two-phase, the pipe geometry, and the flow rates of phases are defined to initiate the operating conditions. The mass flow rates of air and water changed from 0.002 to 0.004 kg/s and 0.672 to 1.334 kg/s, respectively. The impact of properties of the fluid and pipe diameters on two-phase flow configuration is considered to predict the impact of fluid properties on the flow pattern. The findings indicate that as the mass flux increases, the pipe diameters decrease, affecting the configuration of the flow pattern types. T...

Engineering, Technology & Applied Science Research

In an artificial environment, the most important key in the process equipment design is determini... more In an artificial environment, the most important key in the process equipment design is determining gas-liquid two-phase flow frictional pressure drop of pipes. To achieve this, an experimental investigation was carried out in this study to analyze the pressure drops of air-water two-phase flow in a 30mm internal diameter horizontal pipe with a length of 6m at different flow conditions. The study was carried out at 20Co using tap water and air. To cover the slug flow pattern, the volumetric flow rate of water varied from 30 to 80 LPM, and the volumetric flow rate of air from 40 to 200 LPM. Pressure transmitters were used to measure pressure at four different points along the test section, each 2m apart. The results of the experiments were compared to 8 models using 3 distinct methods: Mean Absolute Percentage Error (MAPE), Relative Performance Factor (RPF), and the percentage of data included in the range of the 30% error band. All methods produced similar results, with the Sun-Mish...

The Journal of the University of Duhok, 2020

Weirs are discharge measurement structures have different geometrical shapes. The performances of... more Weirs are discharge measurement structures have different geometrical shapes. The performances of the modified triangular plan form weirs were studied under free-flow condition. Three groups of weirs were tested experimentally. The first group has a flat top; the second has one slope and the third has two slopes. Each group has three vertex angles (60 o , 90 o and 120 o) with constant height. The hydraulic performances of weirs are based on the ability to pass the discharge for certain head flow and on the value of the coefficient of discharge. The values of discharge and the coefficient were compared with earlier studies being carried on conventional normal weir, broad crest, triangular plan-form and different labyrinth weirs. All the groups show better performance than conventional shaped and broad weir. The magnification of the actual discharge to the discharge of broad crested weir is more than one and the best one is the first in the third group, while the vertex angle is (60 o) for the second and third group and (120 o) for the first. The performance of the third group is better than rectangular labyrinth weirs, and it is compatible with the triangular labyrinth. The discharge coefficient decreases with the increase of relative value of the head to the height of weir except for the first group. Equations for predicting coefficient of discharge are proposed within the limitations of this test.

Science Journal of University of Zakho

The aim of this research is to investigate the effect of surface roughness on the performance of ... more The aim of this research is to investigate the effect of surface roughness on the performance of weir and gate. An experimental study in a laboratory flume is carried out to study flow over and under cylindrical weir gate in combined structure as flow measurement device. Four models having different diameters were tested in a laboratory flume. In each model, the surface was roughed four times. The results of the test show logical negative effect of the increase of surface roughness on the performance. The performance of the combined structure improved with decrease ratio of roughness to the upstream head (Ks/H) and with the increase of the total head to the diameter of the weir (H/d). Empirical relations were obtained to estimate the variation of discharge coefficient (Cd) in terms of some dimensionless parameters. Within the limitations of the present experimental work an equation to predict the discharge is proposed with R2 of 0.936. Finely the contribution of the gate increases relative to the weir when the surface roughness increases.

Science Journal of University of Zakho

Engineering, Technology & Applied Science Research

The current study examines the numerical analysis of the laminar flow around a cylinder at variou... more The current study examines the numerical analysis of the laminar flow around a cylinder at various Reynolds numbers (0.1, 1.1, 20, 26, 50, 100, and 195). The research found that a steady state can exist for Reynolds number values of 0.1, 1.1, 20, and 26. However, the flow pattern becomes unstable at Reynolds numbers 50, 100, and 195, leading to the development of the Kármán vortex street. The FEATool Multiphysics software in MATLAB (R2019b) was utilized to numerically solve the steady 2D Navier-Stokes equation. The study compared the estimated drag coefficient to previous experimental and analytical studies in Abaqus/CFD. The lift and pressure coefficients were also calculated, and their results were found to be in strong agreement with earlier investigations in terms of predicting pressure and velocity distribution. The analysis provided insight into how the flow field changes with increasing Reynolds numbers.

Arabian Journal for Science and Engineering, 2016

The aim of the present investigation is to study the effect of both side and bed slopes on the fl... more The aim of the present investigation is to study the effect of both side and bed slopes on the flow over free overfalls in trapezoidal channels, three models of trapezoidal free overfall channels have been built and tested in a laboratory flume. These models had 0.1 m bed width and 3.7 m length with different values of side slope (m = 0.268, 0.577, and 1). Each model had four different bed slopes (S = 0, 0.0033, 0.01, and 0.02). A total of twelve series of the experiments were tested for different ranges of Froude number. Experimental results of all models showed that the variation of (Qm 1.5 / gb 5) with (my b /b) for different values of side slope and different bed slopes is a simple power equation. It was observed that the values of (Qm 1.5 / gb 5) increase with the increase in (my b /b) values. The correlation between (my b /b) with (my c /b) is found to be linear for different bed slopes. The ratio (y b /y c) decreases with the increase of slope (S) with an average value of 0.729 for subcritical and supercritical flow on smooth beds of different slopes. An empirical expression is obtained for the variation of (Qm 1.5 / gb 5) with (my b /b), and (S). The results of the present study have been compared with theoretical and experimental results obtained by other investigators showing well agreements.

Revista de Chimie

Prediction of the flow pattern is a central problms in multi-phase flow analysis. It is a vital p... more Prediction of the flow pattern is a central problms in multi-phase flow analysis. It is a vital point for researchers to accurately predict which flow pattern category types will occur at different flow rates. For this purpose, a mathematical model using the MATLAB (R2017b) computer program is developed for the prediction of gas-liquid two-phase flow patterns in a horizontal pipe with an inner diameter of 30mm under standard conditions. The properties of the air-water two-phase, the pipe geometry, and the flow rates of phases are defined to initiate the operating conditions. The mass flow rates of air and water changed from 0.002 to 0.004 kg/s and 0.672 to 1.334 kg/s, respectively. The impact of properties of the fluid and pipe diameters on two-phase flow configuration is considered to predict the impact of fluid properties on the flow pattern. The findings indicate that as the mass flux increases, the pipe diameters decrease, affecting the configuration of the flow pattern types. T...

Engineering, Technology & Applied Science Research

In an artificial environment, the most important key in the process equipment design is determini... more In an artificial environment, the most important key in the process equipment design is determining gas-liquid two-phase flow frictional pressure drop of pipes. To achieve this, an experimental investigation was carried out in this study to analyze the pressure drops of air-water two-phase flow in a 30mm internal diameter horizontal pipe with a length of 6m at different flow conditions. The study was carried out at 20Co using tap water and air. To cover the slug flow pattern, the volumetric flow rate of water varied from 30 to 80 LPM, and the volumetric flow rate of air from 40 to 200 LPM. Pressure transmitters were used to measure pressure at four different points along the test section, each 2m apart. The results of the experiments were compared to 8 models using 3 distinct methods: Mean Absolute Percentage Error (MAPE), Relative Performance Factor (RPF), and the percentage of data included in the range of the 30% error band. All methods produced similar results, with the Sun-Mish...

The Journal of the University of Duhok, 2020

Weirs are discharge measurement structures have different geometrical shapes. The performances of... more Weirs are discharge measurement structures have different geometrical shapes. The performances of the modified triangular plan form weirs were studied under free-flow condition. Three groups of weirs were tested experimentally. The first group has a flat top; the second has one slope and the third has two slopes. Each group has three vertex angles (60 o , 90 o and 120 o) with constant height. The hydraulic performances of weirs are based on the ability to pass the discharge for certain head flow and on the value of the coefficient of discharge. The values of discharge and the coefficient were compared with earlier studies being carried on conventional normal weir, broad crest, triangular plan-form and different labyrinth weirs. All the groups show better performance than conventional shaped and broad weir. The magnification of the actual discharge to the discharge of broad crested weir is more than one and the best one is the first in the third group, while the vertex angle is (60 o) for the second and third group and (120 o) for the first. The performance of the third group is better than rectangular labyrinth weirs, and it is compatible with the triangular labyrinth. The discharge coefficient decreases with the increase of relative value of the head to the height of weir except for the first group. Equations for predicting coefficient of discharge are proposed within the limitations of this test.

Science Journal of University of Zakho

The aim of this research is to investigate the effect of surface roughness on the performance of ... more The aim of this research is to investigate the effect of surface roughness on the performance of weir and gate. An experimental study in a laboratory flume is carried out to study flow over and under cylindrical weir gate in combined structure as flow measurement device. Four models having different diameters were tested in a laboratory flume. In each model, the surface was roughed four times. The results of the test show logical negative effect of the increase of surface roughness on the performance. The performance of the combined structure improved with decrease ratio of roughness to the upstream head (Ks/H) and with the increase of the total head to the diameter of the weir (H/d). Empirical relations were obtained to estimate the variation of discharge coefficient (Cd) in terms of some dimensionless parameters. Within the limitations of the present experimental work an equation to predict the discharge is proposed with R2 of 0.936. Finely the contribution of the gate increases relative to the weir when the surface roughness increases.

Science Journal of University of Zakho