Stagnation-point flow of a viscoelastic fluid towards a stretching surface

An analysis is made of the steady two-dimensional stagnation-point flow of an incompressible viscoelastic fluid over a flat deformable surface when the surface is stretched in its own plane with a velocity proportional to the distance from the stagnation-point. It is shown that for a viscoelastic fluid of short memory (obeying Walters’ B′ model), a boundary layer is formed when the stretching velocity of the surface is less than the inviscid free-stream velocity and velocity at a point increases with increase in the elasticity of the fluid. On the other hand, an inverted boundary layer is formed when the surface stretching velocity exceeds the velocity of the free stream and the velocity decreases with increase in the elasticity of the fluid. A novel result of the analysis is that the flow near the stretching surface is that corresponding to an inviscid stagnation-point flow when the surface stretching velocity is equal to the velocity of the free stream. Temperature distribution in the boundary layer is found when the surface is held at constant temperature and surface heat flux is determined. It is found that temperature at a point decreases with increase in the elasticity of the fluid.     

A spectral finite element for analysis of wave propagation in uniform composite tubes

A spectral finite element model (SFEM) for analysis of coupled broadband wave propagation in composite tubular structure is presented. Wave motions in terms of three translational and three rotational degrees of freedom at tube cross-section are considered based on first order shear flexible cylindrical bending, torsion and secondary warping. Solutions are obtained in wavenumber space by solving the coupled wave equation in 3-D. An efficient and fully automated computational strategy is developed to obtain the wavenumbers of coupled wave modes, spectral element shape function, strain-displacement matrix and the exact dynamic stiffness matrix. The formulation emphasizes on a compact matrix methodology to handle large-scale computational model of built-up network of such cylindrical waveguides. Thickness and frequency limits for application of the element is discussed. Performance of the element is compared with analytical solution based on membrane shell kinematics. A map of the distribution of vibrational modes in wavelength and time scales is presented. Effect of fiber angle on natural frequencies, phase and group dispersions are also discussed. Numerical simulations show the ease with which dynamic responses can be obtained efficiently. Parametric studies on a clamped-free graphite-epoxy composite tube under short-impulse load are carried out to obtain the effect of various composite configurations and tube geometries on the response.     

Quantitative Analysis of Corosolic Acid,a Type-II Anti-Diabetic Agent,in Different Parts of Lagerstroemia speciosa Linn.

JPC – Journal of Planar Chromatography – Modern TLC - An HPTLC method has been established for rapid and simple quantitative determination of corosolic acid, a type-II (non-insulin...     

Dissolution of Ca3(AsO4)2 · 2H2O in the system CaOAs2O5H2O at 35, 40, 45 and 50°C and the related thermodynamic data

Calcium arsenate dihydrate is precipitated at pH 7.0 and its dissolution in aqueous solutions at temperatures of 35, 40, 45 and 50°C and a pH of between 3.0 and 8.0 is investigated. The thermodynamic parameters ΔG⁰, ΔS⁰ and ΔH⁰ for the process are evaluated. Temperature dependence of solubility is obtained by the equations ?log K_TCA = $\text{9078.138}\text{T}$ ? 34.0468 + 0.0821421 T     

A novel study of charged carbon clusters using a tandem Van de Graaff accelerator

A conventional tandem Van de Graaff accelerator is used to produce charged carbon cluster beams. The unique capability of the method for studying highly charged clusters unaccessible to other methods of producing cluster beams is demonstrated.     

A note on the unsteady motion of a viscous conducting liquid between two porous concentric circular cylinders acted on by a radial magnetic field

In this note the author has investigated some problems of a flow of conducting liquid through two porous non-conducting infinite circular cylinders rotating with various angular velocities for some time in the presence of a radial magnetic field.It is assumed that the rate of suction at the inner cylinder is equal to the rate of injection at the outer cylinder. Furthermore the induced electric and magnetic fields are neglected.Nomenclature a, b radii of coaxial cylinders - h ₁, h ₂ constants - m, n constants - P hydrostatic pressure - t time - A, B functions of r and b - B ₀ magnetic induction vector B ₀= _e H - H magnetic field vector - H intensity of magnetic field - L, M functions of a and b - S Suction parameter - Coefficient of viscosity - _e magnetic permeability - Kinematic coefficient of viscosity - density of liquid - conductivity of liquid - Small time - Constant - ₁, ₂ angular vrlocities - , ₁, ₂ angular velocities.     

Studies in the hydrolysis of metal ions

The hydrolysis of cupric ion has been studied at various ionic strengths (0·01, 0·05, 0·1 and 0·5 M). The results are analyzed employing ‘core + links’ theory, log-log plot, normalization plot, and extrapolation method for obtaining the pure mononuclear curve. The stability constants of Cu₂(OH) ₂ ⁺⁺ , Cu₃(OH) ₄ ⁺⁺ , Cu(OH)⁺ and Cu(OH)₂ have been reported.     

Spectrophotometric and potentiometric investigations of copper (II)-Ethanolamine complexes

Spectrophotometric and potentiometric investigations have been carried out on copper-diethanolamine system. Job plots at 900, 900 and 580 mμ have indicated the formation of CuD⁺⁺, CuD₂ ⁺⁺ and CuD₃ ⁺⁺. Then- pA curves obtained indicate the formation of CuD⁺⁺, CuD₂ ⁺⁺, CuD₃ ⁺⁺, CuDOH⁺, CuD₂OH⁺ and CuD₃OH⁺. Then- pA curves have been analyzed to obtain the stability constants of these complexes. Absorption curves of pure complexes have been computed by a graphical method. Gaussian analysis of the absorption curves of pure and hydroxy complexes show the presence of a second band, indicating that the structure is that of a distorted octahedron.     

Effect of structure and concentration of polymer, metal ion and pH of the medium on the fluorescence characteristics of hyperbranched polyamines

A series of hyperbranched polyamines have been prepared by the reported method. All these polyamines exhibit fluorescence at about 350-650 nm with maximum intensity at about 450 nm. The study shows that the fluorescence intensity and the range of wavelength of fluorescence are strongly influenced by the structure of the hyperbranched polyamines. The effect of concentration of the polymer, pH of the medium and metal ion has also been investigated on the fluorescence characteristics of sulfone containing hyperbranched polyamine (Ps), as it shows the best result among the studied polymers. The results show that the intensity of fluorescence increases with the decrease of concentration (5-0.1 g/L in N,N′-dimethyl sulfoxide) of polymer and with the increase of pH (3.1-11.6) of the medium. The quenching of fluorescence increases with the increase of concentration of Cu²⁺ ions (0.01-0.04%). The hyperbranched polyamine (Ps) has also been end capped with benzoyl chloride and 4-hydroxybenzaldehyde to study the influence of end groups. The results showed that the structure of end capped compounds has prominent role to influence fluorescence characteristics of this hyperbranched polyamine.