Effects of the Hydro Anisotropy and the Magnetic Field on the Dynamic Thermo-Bi-Diffusive Flow in a Horizontal Cavity Confining a Porous Medium Saturated by a Binary Fluid

We analyze analytically the effects of anisotropy in permeability and that of a transverse magnetic field on thermal convection in a porous medium saturated with a binary fluid and confined in a horizontal cavity. The porous medium, of great extension, is subjected to various conditions at the thermal and solutal boundaries. The axes of the permeability tensor are oriented obliquely with respect to the gravitational field. Based on a scale analysis, the velocity, temperature, and heat and mass transfer rate fields were determined. These results were validated by the study of borderline cases which are: pure porous media and pure fluid media discussed in the literature. It emerges from this study that the anisotropy parameters influence the convective flow. The application of a transverse magnetic field significantly reduces the speed of the flow and thereby affects the temperature field and the rate of heat and mass transfer.

Assessment of stratification of the breeds of the underground cavity roof

Authors of the research consider the approach to the assessment of possibility of formation of stratification and shift cracks in the roof of extended horizontal cavity, based on the method of boundary elements. The algorithm implements the iterative procedure of variation of the formed crack length with control of tension in its tip. At the same time, the angle of the crack coasts closing is defined by the tensile strength of the layer material. The crack with smooth closing of coasts is formed in case of equality to zero this durability. The mechanism of failure forming over the developed space with vertical pipe type walls is considered. The results received by the authors, can be useful as the offered approach allows to model the destructions localization in the massif of rocks, location and sizes of the arising cracks of stretching and shift if there are strength defects in the massif

The Effects of Internal Heat Generation or Absorption on Mixed Convection in a Lid-Driven Rectangular Cavity using Finite Volume Method

Mixed convection heat transfer in cavities is a significant phenomenon in numerous engineering fields, such as nuclear reactors, solar energy storage, and heat exchangers. Despite acknowledging that a square is a basic shape found in these systems, not all the figures are geometrical. Less attention was given to the rectangle cavity even though it could be found in these systems. Various internal reactions could occur inside the systems, especially in geothermal heat exchangers. Therefore, this research aims to analyze the effect of internal heat generation or absorption in a two-dimensional (2D) horizontal cavity to the fluid flow and heat transfer process numerically. The vertical walls are well insulated. Meanwhile, the top and bottom walls are kept at and , respectively, where . The top wall moves at a constant speed from left to right. The finite volume method (FEM) and SIMPLE algorithm are employed to discretize the governing equations. Next, the algebraic equations are solved iteratively using the tri-diagonal matrix algorithm (TDMA). The influences of heat generation or absorption parameters are investigated in terms of the flow, heat transfer, and Nusselt number. The numerical results are plotted in the form of streamlines and isotherms. It is found that the presence of heat generation or absorption has a significant effect on the fluid flow and heat transfer process in the horizontal cavity. Overall, for internal heat generation, the heat transfer rate decreases, while the opposite pattern can be observed for the case of internal heat absorption. However, for Ri = 10.0, as the heat generation's value increases from 2 to 4, the heat transfer rate is the same.

The crystal structure of benzophenone synthase from Garcinia mangostana L. pericarps reveals the basis for substrate specificity and catalysis

Benzophenone synthase (BPS) catalyzes the production of 2,4,6-trihydroxybenzophenone via the condensation of benzoyl-CoA and three units of malonyl-CoA. The biosynthetic pathway proceeds with the formation of the prenylated xanthone α-mangostin from 2,4,6-trihydroxybenzophenone. Structural elucidation was performed to gain a better understanding of the structural basis of the function of Garcinia mangostana L. (mangosteen) BPS (GmBPS). The structure reveals the common core consisting of a five-layer αβαβα fold as found in other type III polyketide synthase enzymes. The three residues Met264, Tyr266 and Gly339 are proposed to have a significant impact on the substrate-binding specificity of the active site. Crystallographic and docking studies indicate why benzoyl-CoA is preferred over 4-coumaroyl-CoA as the substrate for GmBPS. Met264 and Tyr266 in GmBPS are properly oriented for accommodation of the 2,4,6-trihydroxybenzophenone product but not of naringenin. Gly339 offers a minimal steric hindrance to accommodate the extended substrate. Moreover, the structural arrangement of Thr133 provides the elongation activity and consequently facilitates extension of the polyketide chain. In addition to its impact on the substrate selectivity, Ala257 expands the horizontal cavity and might serve to facilitate the initiation/cyclization reaction. The detailed structure of GmBPS explains its catalytic function, facilitating further structure-based engineering to alter its substrate specificity and obtain the desired products.

Effect of the Soil Inclination on Natural Convection in Half-Elliptical Greenhouses

A numerical study of the natural convection of laminar heat transfers in the stationary state in a half-elliptic inclined cavity, which represents a continuation of the work done, we studied the influence of the tilt of the cavity by varying the angle — entered 0 degrees, which corresponds to the horizontal cavity, up to 15 degrees. For each value of δ we varied the Rayleigh number from 2.13 103 to 106. The system of equations governing the problem solved numerically by the fluent calculation code based on the finite volume method. Based on the Boussinesq approximation. Both bottom and upper walls maintained at a constant temperature. The interest of this study is to see the influence of the tilt of the half-elliptic cavity on the structure of the flow and the distribution of temperature. These results can exploited in semi-elliptic agricultural greenhouses that rest on sloping soils. We chose a Prandtl number 0.71 that corresponds to the air. Keywords: Heat transfer; half-elliptical; Natural convection; Laminar flow; Multicellular; CFD simulation