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An effective mass transfer intensification method was proposed by embedding different triangular obstacles to improve the gas–liquid mass transfer efficiency in microchannel. The influences of triangle obstacles configuration, obstacle interval and gas flow rate on the volumetric mass transfer coefficient, pressure drop and energy consumption were investigated experimentally. The enhancement factor was used to quantify the mass transfer enhancement effect of triangle obstacles. It was found that the isosceles or equilateral triangle obstacles are superior to the rectangular obstacles. The maximum enhancement factor of equilateral triangle obstacles was 2.35. Considering comprehensively mass transfer enhancement and energy consumption, the isosceles triangle obstacle showed the best performance, its maximum enhancement factor was 2.1, while the maximum pressure drop increased only 0.41 kPa (22%) compared to the microchannel without obstacles. Furthermore, a micro-particle image velocimetry (micro-PIV) was utilized to observe the flow field distribution and evolution, in order to understand and analyze the enhancement mechanism. The micro-PIV measurement indicated that the obstacle structure could induce the formation of vortex, which promotes convective mass transfer and thins the flow boundary layer, accordingly, the gas–liquid mass transfer efficiency is remarkably improved. This study can provide theoretical guidance and support for the design and optimization of microchannel with triangular obstacles.

The present study aims to explore the buoyancy-driven convective phenomena of nanofluid flow in a cavity of an isosceles triangle with an inverted triangular heat source under the effect of a sloped magnetic field. The cases of different heating loads are analyzed considering various sizes of the heating triangle. The outer triangular cavity is kept at a lower temperature; whereas the inner inverted triangular is maintained as the isothermal heat source. Space in-between the inner and other triangle is filled with nanofluid (Al2O3-water). Finite element methodology is adapted to compute the coupled transport equations numerically. The convective phenomena and associated heat transfer characteristics are examined systematically for a range of control parameters like Rayleigh numbers (103–106), Hartmann number (0–70), and magnetic field inclination angle (0−180°), and the size of the inner inverted triangular heat source. The illustrations of local distribution of streamlines, isotherms, entropy generation are presented along with the average Nusselt number, Nu. It shows that the size of the inner triangular heat source controls the overall thermal behavior. The maximum convective heat transfer is obtained with the least flow obstruction (i.e. smaller size of the inner triangle). The study of magnetic field inclination shows that maximum heat transfer is obtained at an inclination of 90° and minimum flow obstruction.

Optical performances of 950 nm p-side up photonic crystal surface emitting lasers (PCSELs) with different types of air holes are numerically and experimentally investigated. Simulation results show an obvious distinction between effective index method and three dimensional finite-element method (FEM). Measured experiments including wavelength, threshold, and slope efficiency can well meet the FEM numerical predictions. It further reveals that the B mode dominates the laser action and the PCSELs accompanying with equilateral triangle and right isosceles triangle holes possess a lower threshold current and higher radiation than symmetric circle holes. The output power can be further enhanced by increasing the filling factor of air holes before the regrowth process.

We examine the aesthetic characteristics of row tile patterns defined by repeating strips of polygons. In experiment 1 participants rated the perceived beauty of equilateral triangle, square and rectangular tilings presented at vertical and horizontal orientations. The tiles were shifted by one-fourth increments of a complete row cycle. Shifts that preserved global symmetry were liked the most. Local symmetry by itself did not predict ratings but tilings with a greater number of emergent features did. In a second experiment we presented row tiles using all types of three- and four-sided geometric figures: acute, obtuse, isosceles and right triangles, kites, parallelograms, a rhombus, trapezoid, and trapezium. Once again, local polygon symmetry did not predict responding but measures of correspondence between local and global levels did. In particular, number of aligned polygon symmetry axes and number of aligned polygon sides were significantly and positively correlated with beauty ratings. Preference was greater for more integrated tilings, possibly because they encourage the formation of gestalts and exploration within and across levels of spatial scale.

The solution accuracy based on finite element interpolation strongly depends on mesh quality. Thus, the numerical manifold method advocates that if a finite element mesh is selected as the mathematical cover, the mesh should be uniform, where all elements are congruent squares or isosceles right triangles for two-dimensional problems. However, the elements close to the points of stress concentrations or singularities must be smaller than those further away from these points. This leads to an irregular mesh in which a few nodes of certain small elements are hung on the edges of adjacent larger elements. This study implements local refinement with arbitrary k-irregular meshes by selecting piecewise polynomials as the local approximations over physical patches and enforcing appropriate constraints on the piecewise polynomials. All the elements are ordinary isoparametric elements, and elements with variable numbers of nodes on edges are not required. No linear dependency issue exists. Furthermore, refinement with any number of mesh layers is developed so that solution error can be distributed as uniformly as possible. Typical examples with different singularities are designed to illustrate the effectiveness of the proposed procedure.