The effects of transpiration on the boundary layer flow and heat transfer over a vertical slender cylinder

This paper deals with a theoretical (numerical) analysis of the effects that blowing/injection and suction have on the steady mixed convection or combined forced and free convection boundary layer flows over a vertical slender cylinder with a mainstream velocity and a wall surface temperature proportional to the axial distance along the surface of the cylinder. Both cases of buoyancy forces aid and oppose the development of the boundary layer are considered. Similarity equations are derived and their solutions are dependent upon the mixed convection parameter, the non-dimensional transpiration parameter and the curvature parameter, as well as of the Prandtl number. Dual solutions for the previously studied mixed convection boundary layer flows over an impermeable surface of the cylinder are shown to exist also in the present problem for aiding and opposing flow situations.     

Transition events fluctuations in jump markovian dynamics. A general approach to Šolc's problem

We introduce a new formalism for computing the moments of transition events for nonhomogeneous Markov jump processes. Our method is applied directly to the master equation and does not involve the use of diffusion approximation. The general theory is applied to produce exact expressions for means and dispersions. For time homogeneous Markov processes with a finite number of connected states we are able to prove that both means and dispersions asymptotically increase linearly in time.     

Catalytic Properties of (Fe,Al)-MCM-41 in Conversion of CO and Light Alkanes with Participation of Nitrogen Oxides

We used X-ray phase analysis, IR, X-ray photoelectron, and NMR spectroscopy to characterize a synthesized mesoporous material (Fe,Al)-MCM-41. As a result of a certain combination of structural, acidic, and oxidation–reduction properties of the surface, (Fe,Al)-MCM-41 exhibits catalytic activity in reactions with participation of nitrogen oxides, in particular partial oxidation of propane by nitrogen(I) oxide to isopropanol.     

Thermal interaction between free convection and forced convection along a vertical conducting wall

A theoretical study is presented in this paper to investigate the conjugate heat transfer across a vertical finite wall separating two forced and free convection flows at different temperatures. It is assumed that the heat conduction in the wall is only in the transversal direction. We also assume that countercurrent boundary layers are formed on the both sides of the wall. The governing equations of this problem and their corresponding boundary conditions are all cast into a dimensionless form by using a non-similarity transformation. These resulting equations, which are singular at the points ξ_c=0 and 1, are solved numerically using a very efficient singular perturbation method. The effects of the resistance parameters and of the Prandtl numbers on heat transfer characteristics are investigated and presented in a table and ten figures. Received on 8 April 1998     

g-Jitter induced free convection near a stagnation point

 The effect of a small but fluctuating gravitational field, characteristic of g-jitter, on the flow near the forward stagnation point of a two-dimensional symmetric body resulting from a step change in its surface temperature has been considered in this paper. The transformed equations are solved numerically by a very efficient finite-difference method known as the Keller-box technique to investigate the effects on the shear stress and rate of heat transfer of variations in the Prandtl number, Pr, the forcing amplitude, a, and the forcing frequency, ω. It has been found that these parameters affect considerably the shear stress and the rate of heat transfer. Received on 28 February 2000