Patents and Papers
2013Afify, R.S., A
modified method for the formation and follow up hydrogen bubbles in “Hydrogen Bubble Generator” apparatus, Arab Republic of Egypt, Ministry of State for Scientific Research and Technology, Academy of Scientific Research and Technology, Egyptian Patent Office, patent no. 26319, (2013).2013Afify, R.S.
A new method for flow simulation, Arab Republic of Egypt, Ministry of State for Scientific Research and Technology, Academy of Scientific Research and Technology, Egyptian Patent Office, under construction.
Publications
2006Elshorbagy, K.A., Wahba, E.M., Afify, R.S.
“On The Critical Reynolds Number For Vortex Shedding Past Bluff Bodies”, 8th International Congress of Fluid Dynamics & Propulsion, ICFDP 8-EG-151, Sharm El-Shiekh, Sinai, Egypt, (December 14-17, 2006).2008Elshorbagy, K.A., Wahba, E.M., Afify, R.S.
“Vortex Shedding past Bluff Bodies in The Moderate Reynolds Number Range”, ICERD4-1412, The Fourth International Conference on Energy Research & Development, Kuwait, (2008).2010Elshorbagy, K.A., Wahba, E.M., Afify, R.S.
“Visualization Versus CFD Simulation of Laminar Flow past Bluff Body”, 10th International Congress Fluid Dynamics (ICFD 10), ICFD10-EG-3040, Ain Sokhna, Egypt, (December 16-19, 2010).2012Elshorbagy, K.A., Wahba, E.M., Afify, R.S.
“Volume Flow Rate Assessments from Vortex Shedding”, RETBE’12 9th International Conference, Role of Engineering towards a better Environment, Alexandria, Egypt, No.54, (December 22-24, 2012).2013Elshorbagy, K.A., Afify, R.S.
“Numerical Prediction of Drag Coefficient of Different Bluff Bodies in Free and Confined Flows”, 1st International Symposium on Computational and Experimental Investigations on Fluid Dynamics, CEFD’2013, Sfax, TUNISIA, (March 18-20, 2013).2013Elshorbagy, K.A., Afify, R.S.
“Numerical Prediction of Effect of Adding Second Similar Shape Bluff Body on Drag Coefficient”, 11th International Congress Fluid Dynamics (ICFD 11), Alexandria, Egypt, (December 19-21, 2013).2013Elshorbagy, K.A., Afify, R.S.
“Numerical Prediction of Effect of Adding Bluff Body After Circular Shape on Drag Coefficient”, 11th International Congress Fluid Dynamics (ICFD 11), Alexandria, Egypt, (December 19-21, 2013).
Attended Conferences
201010th International Congress Fluid Dynamics (ICFD 10)
Ain Sokhna, Egypt, (December 16-19, 2010).2012RETBE’12 9th International Conference, Role of Engineering towards a better Environment
Alexandria, Egypt, No.54, (December 22-24, 2012).201311th International Congress Fluid Dynamics (ICFD 11)
Alexandria, Egypt, (December 19-21, 2013).
Helped in Preparing Conferences
201311th International Congress Fluid Dynamics (ICFD 11)
Alexandria, Egypt, (December 19-21, 2013).
Paper Under Preparation
- Elshorbagy, K.A., Afify, R.S., “Numerical Prediction of Effect of Adding Second Similar Shape Bluff Body on Strouhal number”…
- Elshorbagy, K.A., Afify, R.S., “Numerical Prediction of Effect of Adding Bluff Body After Circular Shape on Strouhal number”…
- Elshorbagy, K.A., Afify, R.S., “Review on Vortex Shedding”…
PHD
Vorticity Shedding in Vortex Flowmeters – Numerical Simulation and Experimental Verification
ABSTRACT
In the present thesis, numerical and experimental investigations are conducted to study the flow around bluff bodies in a wide range of Reynolds number. In numerical investigations, two main flow types are considered, free flow and confined flow. A single bluff body of different shapes is employed in the case of free flow. In the case of confined flow, single and dual bluff bodies are considered. Five basic bluff body shapes are used, namely circular, square, triangular, inverted triangular and T-shaped cylinders. In dual bluff bodies' investigations, only circular cylinders are considered. The experimental investigations comprise two approaches. In the first, "Hydrogen Bubble Flow Visualization System" is used to simulate the flow around bluff body and video-camera shots are utilized to photographically store visualized streamlines. Secondly, experimental Water Channel is used to investigate the applicability of vortex shedding frequency measurement in detecting volume flow rate in a confined flow. In the case of free flow past bluff bodies, the flow is numerically simulated in the range of Reynolds number Re107. In the Reynolds number range (Re 40), the relation between Reynolds number and vortex length for each shape is obtained. For such low Reynolds numbers, the flow is laminar steady and a separation region is visible in the wake behind the bluff body. In this region, two symmetric vortices are formed. The size of the vortex increases with increasing Reynolds number for all shapes. Hydrogen Bubble Flow Visualization photographs are compared with numerical streamline plots and are found markedly similar. At a certain critical Reynolds number, the steady flow past the bluff body becomes unstable and the flow bifurcates to the unsteady state. The critical Reynolds number for each shape is evaluated and the effect of bluff body geometry on the value of this critical Reynolds number is identified. The critical Reynolds number for the shapes under consideration ranges between 37 and 46. As the Reynolds number is further increased, vortices are shed in the wake of all considered body shapes. The Strouhal number for such vortex shedding phenomena is calculated and the effect of bluff body shape on the value of this number is demonstrated in the Reynolds number range (100 Re 2 x 105). Streamlines and vorticity contours for the flow around the different bluff body shapes are plotted. Visualization photographs indicate a flow behavior which is rather similar to that numerically predicted. . On further increasing Reynolds number, the flow becomes turbulent. Using four different schemes, namely, Spalart-Allmaras, k-, SST k-, and RSM models, turbulent flow simulations are performed in the Reynolds number range (104 Re 107) and values of Strouhal number are calculated. Comparisons between results using these schemes and other published data show that the k- and SST k- models are rather suitable than the RSM and Spalart-Allmaras models for the considered cases. Streamlines and vorticity contours for the flow around the different bluff body shapes at Re = 106 are plotted. Periodicity of vortex shedding in the flow field is proved to exist for all shapes under consideration. In the case of confined flow, the Strouhal number is calculated using k-ε model for domain widths (H) equal to three and four times the frontal length of the bluff body, (Blockage ratio B = 33.3% and B = 25%, respectively). The relation between Reynolds number and Strouhal number is obtained for each shape of the five bluff bodies in the Reynolds number range of (103 Re 108). Streamlines and vorticity contours for the flow around different bluff bodies are plotted. The resulted vortices are shown to generally have perfect periodicity. Considering dual circular cylinder bodies, the relation between Reynolds number and Strouhal number, for center to center distance of twice and three times the frontal length of either bluff bodies, is compared with that of the single body in the Reynolds number range of (103 Re 108). Plotted streamlines and vorticity contours demonstrated a perfect periodicity of vortex shedding for the studied shapes. Finally, experimental work, carried out in the water channel, is directed towards measuring the frequency of vortex shedding in the wake of bluff bodies with frontal length one fourth the domain's width. Knowing the value of Strouhal number from numerical results (case of confined flow) and using the measured frequency of vortex shedding, the volume flow rate in the channel is determined and a discharge coefficient is established for every shape of bluff bodies. Results indicate that the triangular shape is the most convenient geometry for use in vortex shedding flowmeters. Supervisors: Prof. Dr. Kamel Elshorbagy. Ass. Prof. Essam Wahba.Master
Numerical Study of Belt Skimmer Performance
ABSTRACT
With the recent increases in sea traffic, these waterways have become a prime site for oil spill pollution. Tanker transportation and oil platforms are sources of potential risks of oil pollution. In case of accidental marine pollution, the authorities in charge of pollution shall response. Ideally there are six response alternatives to combat an oil spill: 1- Monitor and evaluate. 2- Disperse the oil with chemicals. 3- Contain and recover the oil at sea. 4- Protect vulnerable resources. 5- Burning, and 6- Clean up the shoreline. These alternatives are well known. Some of them can cause more damage to the environment than the presence of the spill itself such as the chemical dispersants or burning the oil in the sea. Others prefer mechanical devices such as skimmers. Each of which has its own applications depending on manpower and the proper use of the selected techniques. The objective of this work is to find the effect of the working parameters on the belt performance and to simulate the scene, which had seen in the experimental work. The parameters that affect on belt skimmer performance are namely the belt speed (Vbelt), the belt inclination angle (), the oil viscosity (), the oil film thickness (T), and the oil surface tension (). Starting from N.S.E (Navier Stocke’s Equations) in the incompressible fluid flow form with a constant viscosity. Using assumptions and boundary conditions (B.C.) to get the equations of velocity distribution and volume flow rate for the flow over belt surface in the downward and upward directions and to get the equations of motion for the flow over water surface.- For the flow over belt surface, the velocity distribution and the skimmed flow can be theoretically estimated. Also, an empirical formula for the oil height over belt surface was obtained.
- For the flow over water surface, a model of grids is developed for the recovery area (the area between the boom and the skimmer). The model is a two-dimensional finite element model. After a finite element mesh has been constructed and boundary conditions have been defined, the flow velocity at each grid point can be computed. So, the model can simulate the oil circulation over water surface, draw velocity distribution through the oil film thickness and calculate the compensating oil.
Graduation Porject
Central Air Conditioning Programming and Applications
Supervisor: Dr. Akram Abdou.