Numerical Investigation was done for steady state laminar mixed convection and thermally and hydrodynamic fully developed flow through horizontal rectangular duct including circular core with two cases of time periodic boundary condition, first case on the rectangular wall while keeping core wall constant and other on both the rectangular duct and core walls. The used governing equations are continuity momentum and energy equations. These equations are normalized and solved using the Vorticity-Stream function and the Body Fitted Coordinates (B.F.C.) methods. The Finite Difference approach with the Line Successive Over Relaxation (LSOR) method is used to obtain all the computational results the (B.F.C.) method is used to generate the grid of the problem. A computer program (Fortan 90) is built to calculate Nusselt Number (Nu) in steady state. The fluid Prandtl number is 0.7 Rayleigh Number 1<Ra<106, Reynolds number 1<Re<2000. For the range of parameters considered, results show that the time periodic boundary condition enhance heat transfer. It is also indicated in the results that heat transfer from the surface of the circle exceeds that of the rectangle duct. Comparisons with other research show good agreement.
The aim of this study was to propose and evaluate an eco-epidemiological model with Allee effect and nonlinear harvesting in predators. It was assumed that there is an SI-type of disease in prey, and only portion of the prey would be attacked by the predator due to the fleeing of the remainder of the prey to a safe area. It was also assumed that the predator consumed the prey according to modified Holling type-II functional response. All possible equilibrium points were determined, and the local and global stabilities were investigated. The possibility of occurrence of local bifurcation was also studied. Numerical simulation was used to further evaluate the global dynamics and the effects of varying parameters on the asymptotic behavior of
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The effect of superficial gas velocity within the range 0.01-0.164 m/s on gas holdup (overall, riser and down comer), volumetric oxygen mass transfer coefficient, liquid circulation velocity was studied in an internal loop concentric tubes airlift reactor (working volume 45 liters). It was shown that as the usg increases the gas holdup and also the liquid circulation velocity increase. Also it was found that increasing superficial gas velocity lead to increase the interfacial area that increases the overall oxygen mass transfer coefficient. The hydrodynamic experimental results were modeled with the available equations in the literature. The predicted data gave an acceptable accuracy with the empirical data.
The final
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Theoretical and experimental investigations of free convection through a cubic cavity with sinusoidal heat flux at bottom wall, the top wall is exposed to an outside ambient while the other walls are adiabatic saturated in porous medium had been approved in the present work. The range of Rayleigh number was and Darcy number values were . The theoretical part involved a numerical solution while the experimental part included a set of tests carried out to study the free convection heat transfer in a porous media (glass beads) for sinusoidal heat flux boundary condition. The investigation enclosed values of Rayleigh number (5845.6, 8801, 9456, 15034, 19188 and 22148) and angles of inclinations (0, 15, 30, 45 and 60 degree). The numerical an
... Show MoreThis research presents the kinetics of the saponification reaction using mixed fats of olein and stearin [in the ratio (3:1)] with NaOH solution. In this reaction, excess solution of NaOH was used to ensure the reaction being irreversible. Three parameters were varied to show their effects on the reaction rate .They are: percentage excess of NaOH solution (10 % - 100 %) , temperature (100-150)oC , and stirring speed (400-1100) rpm. It was noticed that increasing the percentage excess of NaOH solution enhances the rate of reaction while increasing temperature decreases the reaction rate since it is exothermic reaction. Increasing stirring speed also improves the reaction rate because it is mass transfer controlled .Calcu
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Schiff base obtained from the reaction (Trimethoprim) with (sodiumpyruvate ) to produce the ligand [NaL], the reaction was carried out in methanol as a solvent under reflux. The prepared ligand [NaL] was characterized by FT-IR, UV-Vis spectroscopy, 1H,13C-NMR spectra, mass spectra, and melting point.A new mixed ligand complexes have been prepared between ( 8- hydroxyquinolone) and the ligand [NaL] withMn(II).Co(II),Ni(II),Cu(II), (Zn(II) ,(Cd(II)and Pd(II). All the complexes were characterized by spectroscopic methods (FT-IR, UV-Vis spectroscopy), chloride content and melting point ,molar conductance and magnetic susceptibility.These measure- ments showed octahedral geometry around(,Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and Cd2+) ions and square pla
... Show MoreBidentate Schiff base ligand 3-(3,4-Dihydroxy-phenyl)-2-[(4-dimethylamino-benzylidene)-amino]-2-methyl-propionic acid was prepared and characterized by spectroscopic techniques studies and elemental analysis. The Cd(II), Ni(II), Cu(II), Co(II), Cr(III),and Fe(III) of mixed-ligand complexes were structural explicate through Moler conductance , [FT-IR, UV-Vis & AAS], chloride contents, , and magnetic susceptibility measurements. Octahedral geometries have been suggested for all complexes. The Schiff base and its complexes were tested against various bacterial species, two of {gram(G+) and gram(G-)} were shown weak to good activity against all bacteria.