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EN
The free convection boundary layer of water at 4° C from a vertical flat plate with step discontinuities in surface temperature is investigated here. Under a convenient transformation of variabIes, the problem is cast into a pair of partial differential equations, which are numerically solved using the well-known Keller-box method. Temperature and veloeity field developments are presented for various values of the parameter 8w2 whieh represents the step discontinuity in the surface temperature for both Pr=ll.4 and Pr=7. The loeal heat tlux is calculated in a dimensionless form and is plotted vs the streamwise coordinate for both water in the extremum and in normal conditions of density .
EN
In the paper, a dynamic analysis of gas-lubricated hybrid circular bearings is made. The mathematical model is the Reynolds equation in unsteady regimes along with the boundary conditions for a multiple connected domain. Within the hypothesis of a periodic relative motion of bearing surfaces, the method of small perturbations is used. The equations of the model are solved numerically using a difference finite method and finally, the curves of variation of the critical mass versus the eccentricity are obtained.
EN
In hybrid bearings, the carrying effect is produced by supplying under pressure and by the relative motion of the bearing surfaces. Because the pressure distribution in the bearing is the solution to a nonlinear partial differential equation of second order, the two causes cannot be studied separately and solving the problem is a difficult task. The mathematical model considered by us is the Reynolds equation for compressible fluids in a multiple connected domain. The boundary conditions on the inner boundaries are derived from the flow-rate continuity through the supplying orifices and are expressed as nonlinear integral-differential equations, which are solved numerically.
EN
A theoretical study is conducted in this paper for the development of the steady three-dimensional boundary layer, which is induced by a horizontal forced convection flow past an infinitely long vertical cylinder. It is assumed that the cylinder is partially prescribed with a constant heat flux qw, while the other part of the cylinder is held at the ambient temperature T_. It is also assumed that the secondary flow is induced in the boundary layer by the buoyancy forces. A series solution method is used to solve the governing non-linear set of partial differential equations near the thermal leading edge. It is shown that the effect of the horizontal free stream on the boundary layer gradually increases as one moves upward away from the thermal leading edge along the cylinder. The solution has been obtained for different values of the Prandtl number, Pr, and it is shown that for Pr = 0.733 and Pr = 6.7 the present results are in excellent agreement with those known from the literature.
EN
The present paper brings new lights on blood flow patterns in rigid artery bifurcation models, differing in angle of bifurcation. Using the ANSYS 5.4/FLOTRAN package, a numerical analysis in two dimensions was performed, under physiologically relevant flow conditions. For two bifurcation models, one with large angle the other with a small one, the distributions of velocities, shear-stress and pressure in the domain of carotid artery bifurcation have been obtained. It is argued and proved that the vascular geometry at the bifurcation level represents a risk factor in atherogenesis, the relevant factors for this process being the flow separation, reversal flow regions and wall shear stress.
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