Microfluidic devices have many attractive qualities such as low cost, small size, and in-field use. Micromixers are very important components of these devices because affect their efficiency. In a passive mixer, the structural characteristics of the mixer are crucial and must be analyzed. This paper presents a numerical study of the mixing in passive Y-shaped micromixers with a spherical mixing chamber for a volume constrained system. The effect of asymmetric bifurcated ducts, the angle in between the inflow ducts, eccentricity and, obstacles inserted in the mixing sphere, on the mixing efficiency and flow impedance is evaluated. Vortical structures characteristics and the possible occurrence of engulfment are also identified. The results show that flow impedance (pressure drop for unit volumetric flow rate) can be decreased greatly for the same mixing efficiency as the volume of the spherical mixing chamber is 20% of the total volume. Insertion of the obstacles into the sphere mixing chamber decreases the mixing efficiency while they increase the flow impedance. The results also show that spherical mixing chamber enhances mixing efficiency while decreasing flow impedance if the volume reserved for it is greater than a limit value which depends on the diameter and length scale ratios in between the mother and daughter ducts as well as the total volume. Overall, the paper documents the variation of mixing efficiency and flow impedance based on the geometrical parameters of three-dimensional asymmetric passive micromixer with sphere mixing chamber.

A high-temperature gas mixing chamber is a type of mechanical device which has been widely used to obtain airflow at a specific high temperature. When a temperature environment test for aviation equipment is performed, the airflow temperature should exceed 1, 000 K and change fast. However, the existing mixing devices cannot meet the requirements for mixing speed and uniformity of temperature environment tests. To solve the problem of low mixing speed and uniformity, this paper proposes an innovative gas mixing chamber design. The proposed design allows cold and hot gases to be injected in directions perpendicular to each other, which increases the collision and heat exchange of gases with different temperatures. In this way, a faster mixing process and a more uniform outlet temperature field are obtained. Moreover, a genetic optimization method is used to improve the performance of a mixing chamber. This method considers temperature distribution, the velocity distribution of the outlet airflow, and the mixing speed. Simulation results show that the proposed method can reduce the mixing time from 4. 4 s to 2. 3 s, the standard deviation of the outlet temperature distribution from 25. 2 to 14. 7, and the standard deviation of velocity distribution from 1. 3 to 0. 36. The experimental results show good consistency with the simulation results, indicating that the simulation and optimization results are reliable, and the mixing performance of the cold and hot gas mixing chamber is significantly improved by the proposed method. The proposed method is important for optimizing the design of similar orifice plates and flow mixing structures.

This research aims to study the mixing dynamics of granular materials in the Triaxe mixer and compare the effect of operating conditions on the quality of mixing. The discrete element method was used to simulate the mixer and track the motion of particles. The Johnson-Kendall-Robinson model was used for the simulation of the contact of cohesive particles. The results indicate that the most influential parameter on the mixing performance is the rotational speed since raising the rotational speed increases the transferred momentum to the grains. In the specific design of the mixer, the dead zones are reduced, so the fill-level does not have a considerable impact on the homogeneity. Also, the quality of mixing of large particles in this blender is better than the same for smaller particles. The mixer's performance for blending cohesive grains was similar to that for the non-cohesive particles. For both types of solids, the relative standard deviation reached approximately 35% after 70 s. Mixing performances of two sizes of the mixer were compared based on two criteria, the constant impeller speed and constant power per volume of the mixer. The results show that the case of the constant impeller speed can predict the mixing performance of the larger mixer more accurately.

Prediction of the behavior of T-shaped chambers due to their high complexity has always been of great interest to researchers. In this article, based on experimental data and genetic programming, the optimal model was presented for mixing process response. To obtain the system’s behavioral equations, first, using the experimental results and by changing the input variables system, input – output data is extracted. In order to predict the behavior of the system, the equation of input – output data, is derived using genetic programming. To design the structure of genetic programming trees, multi-objective optimization with two objective functions is taken into consideration: model inaccuracy and complexity of structure. By minimizing the objective function at the same time, we are looking for simple equations (minimizing the complexity of the structure) and increasing the accuracy of modeling (minimizing the error). In order to achieve a less complex equation, depth of the generated trees in structure of genetic programming will be minimal. By using multi-objective optimization, optimum set of points have been presented. Comparing the results obtained from the models and real data represents a very good match.

In the current research, numerical analysis was used to investigate the flow behavior through the axial jet-pump with various mixing chamber configurations (straight pipe and straight pipe-diffuser-straight pipe) in the presence of inlet swirling flow and its influence on the pump performance. The effects of introducing inlet swirling flow in the suction chamber and in the motive flow line, are numerically investigated. The optimum swirl angle in the suction chamber is found to be 45o which yields the maximum pump efficiency of 38.08 % for the second configuration of mixing chamber system. Consequently, the inlet swirl generally decreases the desired mixing chamber length. Additionally, the new mixing chamber configuration enhances the mixing process compared with the traditional mixing chamber. On the other hand, imparting a swirl in the motive line inversely affected the pump performance. Engendering a swirl in suction chamber causes an improvement by 12.76 % in the pump efficiency compared to the same pump configuration without swirl. The optimum tail pipe diffuser angle is found to be 3o.

In the present study, the mixing fluids flow in the twin and circular mixers is investigated by using an improved robust weakly compressible Smoothed Particle Hydrodynamics method. In order to remove the Smoothed Particle Hydrodynamics complications and according to a predictive corrective scheme, a robust modified algorithm which uses the advanced second order discretization, pressure velocity decoupling, kernel gradient corrections and shifting algorithm is offered. After the verification and validation of the present algorithm for the moving boundary problems, the present algorithm is applied for investigation of the mixing behaviors of the twoblade circular and twin chamber mixers. By investigation of the mixing paths, the proper geometry for the two-blade mixers is proposed and examined. The effects of the rotation direction of the blades, geometry and Reynolds number on the mixing rate are investigated. The results show that the twin chamber mixer can improve the mixing performance over 60% in comparison with the circular chamber mixer while the case with circular chamber and same direction rotation of the blades has the weakest performance among the cases which have been examined.

A Laser Induced Fluorescence technique (LIF) has been used to study the mixing behavior of two emerging streams in a T-Type mixing chamber. A mixing index on the basis of digital image light intensities is calculated. It has been shown that averaging over more than 800 images leads to a stable mixing index calculation. Moreover, the effect of equal and un-equal flow rates on the mixing behavior of the streams has been studied. The results show that the histograms of the light intensity changes from double peak (unmixed) to a single peak (mixed) at high elevations of the chamber. Mixing index has a linear descending behavior moving toward the cell front wall and it was shown that the mixing index can be reduced up to 50% moving from cell center to near wall region. Moreover, there is a transition zone in both equal and un-equal fluid flow rates in mixing index. It was shown that the third component velocity plays an important role in mixing behavior in T-Type mixing chamber.

The study area is located at the eastern Urmia Lake near Aghgonbad village with 1Km distance from Eslami peninsula. The rocks are under saturated and belonging to the Cenozoic to Pelio-Quaternary with shoshonitic affinities and are phonolite to luecitite. The chondorite normalized REE patterns show LREEs enrichment related to HREEs. Some geochemical characteristics are correlated with continental within-plate setting and have post-collisional resemblance accompany with crustal contamination. Crystal Size Distribution (CSD) patterns have been drawn for leucite, pyroxene and olivine crystals. It is observed that the curve is fractured and curvature for leucite, with fine and coarse grains, that is sign of two magma mixing. But the patterns for olivine and pyroxene are linear. The average times for nucleation, growth and suspension at the chamber for leucite fine grains and olivine are less than 100 years and for pyroxene and coarse leucites residence time are >200 years, if growth rate is 10-11 cm/year. The intercept values calculations show that at least 12 silicate nuclei at the same time was formed, at the chamber.