Critical Mach Numbers of Flow around Two-Dimensional and Axisymmetric Bodies

The paper presents the calculated results obtained by the author for critical Mach numbers of the flow around two-dimensional and axisymmetric bodies. Although the previously proposed method was applied by the author for two media, air and water, this chapter is devoted only to air. The main goal of the work is to show the high accuracy of the method. For this purpose, the work presents numerous comparisons with the data of other authors. This method showed acceptable accuracy in comparison with the Dorodnitsyn method of integral relations and other methods. In the method under consideration, the parameters of the compressible flow are calculated from the parameters of the flow of an incompressible fluid up to the Mach number of the incoming flow equal to the critical Mach number. This method does not depend on the means determination parameters of the incompressible flow. The calculation in software Flow Simulation was shown that the viscosity factor does not affect the value critical Mach number. It was found that with an increase in the relative thickness of the body, the value of the critical Mach number decreases. It was also found that the value of the critical Mach number for the two-dimensional case is always less than for the axisymmetric case for bodies with the same cross-section.

Study on Shear Rheological Behavior of Konjac Glucomannan

Konjac glucomannan (KGM) belongs to pseudoplastic fluid. Remarkable non-linear change tendencies of shear rheological behavior of KGM were detected through analysis of the correlation of viscosity (η)-shear rates and shear stress-shear rates respectively, and its shear rheological curves conformed to the Power Law (τ=ＫDn). The change tendencies of viscosity factor (K) and flow index (n) correlated with concentration and temperature were also obtained, the curves can be fitted by power and quadratic polynomial equation respectively. The acquired non-linear correlation curves of K and n can provide reliable foundation for rational applications of KGM in food industry and its grade estimation.

Quantum Electrodynamics Calculation of Long - Range Interaction of Biopolymers in Intracellular Dispersion Medium

The general Lifshitz theory of van der Waals interaction was used to formulate and compute energies between the nucleotides situated on the opposite ends of a broken DNA helix. Our calculation show that infrared and ultraviolet resonances in the dielectric functions of DNA and the intracellular liquid account for less then 10 percent of the forces of interaction, at a range of 5-15 angstroms, between nucleotides. Thus the fundamental contribution to the interaction is presented by the group of resonances with frequencies of X - ray range. It was shown that during the interaction between thymine - guanine, adenine - guanine and cytosine - guanine there exists a potential barrier which prevents DNA selfrepairing after a mutanous, over a distance of about 7 - 20 angstroms, at the room temperature and with reference to the viscosity factor for pure water. All the remaining pairs of nucleotides have no such barrier. In addition the barrier vanishes and DNA undergoes complete selfrepairing with the decreace in viscosity of intracellular medium.

Coupled Parallel Flows in a Channel and a Bounding Porous Medium of Finite Thickness

The steady laminar flow in a parallel plate channel bounded below by a porous layer of finite thickness and above by a rigid impermeable plate moving with a uniform velocity is studied. The two cases, viz., the porous medium bounded below (i) by a static fluid and (ii) by a rigid impermeable stationary wall, are considered separately. The modified slip condition involving the thickness of the porous layer is derived using the variation of velocity in the porous medium with the proper matching conditions based on the physical considerations. It is shown that when the thickness of the porous layer tends to infinity our modified slip condition tends to the slip condition postulated by Beavers and Joseph [13]. Methods to estimate the viscosity factor λ and relative permeability are discussed. The velocity profiles in the porous layer are shown to exhibit the boundary-layer type very near the porous surface; they increase with increase in depth of the porous medium and decrease with increases in λ. We find that the effect of the finite thickness of the porous medium is significant only for large values of λ and small values of the porous parameter σ.