Applied Mechanics and Materials Vols. 275-277

Abstract: For simulating the wind load strength effect so as to detect the opening and closing performance of the aerodynamic braking device and the reliability of its opening and closing mechanism with the wind load caused by high speed flow field, the wind load test-bed is to build. Wind channel, as the equipment to turn a high pressure flow into a relatively high speed advection, is one of its important components. This paper focuses on the design of the shape of the wind channel. By the means of flow field simulation analysis, with the indexes of the wind load size, the pressure distribution and the flow equality, the shape optimization of the wind channel is realized.

Abstract: The governing equations and mathematical model of the stability parameter H are given in bipolar coordinate system when power law fluid flows in annulus with the inner cylinder executing a planetary motion in this paper. The stability parameter H of power law fluid in both wide clearance and thin clearance in annulus with the inner cylinder executing a planetary motion is numerically calculated by finite difference method, the influences of the revolution velocity, rotation velocity, the eccentric distance and the pressure gradient on the stability parameter are analyzed. The results indicate that the eccentricity and the pressure gradient are main influence factors on it. The critical value of stability parameter for the flow of power-law fluid with the inner cylinder executing a planetary motion is 404 by means of experiment of CMC aqueous solution in annulus with the inner cylinder executing a planetary motion.

Abstract: In this paper, the stress equation is available by introducing the principle of effective stress in porous media into fluid-solid coupling seepage and considering the conditions of equilibrium. According to the continuity equation of fluid mechanics, considering the interactions between shale gas and rock-soil body, the differential equation of seepage flow is obtained. Through introducing the velocity component of rock particles into the seepage field, the pore fluid pressure in seepage field is introduced into the deformation field, so as to realize the interaction between the fluid-solid coupling seepage. Based on auxiliary boundary conditions in the above equations, the paper establishes the integrated fluid-coupling seepage mathematical model of shale gas, and it will provide the corresponding theoretical and realistic significance in the development of shale gas.

Abstract: The aerodynamics characteristics of square Mira model were researched by simulation, the drag coefficient and the aerodynamic characteristics around model were achieved with analysis of velocity and pressure distribution. Based on results, the angle of rear wind window, the angle of underbody diffuser and the front transition radius were changed, the drag and lift coefficients were achieved. The conclusions provide reference for how to reduce drag coefficient of SUV

Abstract: Hemodialysis is a process to clean the metabolic wastes inside human body. Our previous researches on this topic fundamentally used contemporary numerical methods (such as CFD (computational fluid dynamics), MD (molecular dynamics), etc.) to study the ultra-filtration properties and made several progresses. However, our step-forward MD study on amino-acid leaking problem which natively exists during the hemodialysis process makes the numeral calculations more complicated. To control the heavy computation load during MD simulation, in this paper, a novel parallel domain separation scheme is proposed and its optimization method is further discussed. The unique feature of this scheme is that it introduces fibers as well as "compute shaders" into the parallel computation architecture. And the further application of this parallel scheme could form a new concept of MD simulation.

Abstract: In this paper, wave propagation in poroelastic medium is simulated with a staggered-grid finite-difference method. The formulation is discretized based on the second-order Biot’s equations rather than the corresponding velocity-stress form. In order to eliminate boundary reflections, the PML method is applied. Numerical computations are implemented and the results show the correctness and effectiveness of the schemes presented in this paper.

Abstract: It exist several strategies to mix two fluids in a micro channel. The way micro bubble vibrations influence the mixing flow is still unknown. This paper presents numerical simulations of the mixing within the micro device with and without micro bubble vibrations. A simplified model of the microchannel has been successfully employed, via using moving panels instead of sidewall-trapped bubbles oscillation. The simulation method, which exerted sinusoidal movements on the panels to approximately represent the ultrasonic vibrations of microbubbles, has been used to fully solve the Navier-Stokes equations. The comparison between simulations and previously reported experiments, in terms of flow pattern and the mixing performance within micro channel, exhibits a very good agreement. When ultrasonic vibrations of a frequency of 80 kHz and amplitude of 8 μm were applied, the mixing flow patterns have been reproduced and with a little differences comparing to the experimental results. All of these studies have revealed the mix mechanism under the micrometer scale in a certain way.

Abstract: The dynamics force of iced-conductor is the driving force of galloping, its variation is depended on the aerodynamic character of iced conductor. The aerodynamic character of iced conductor is the key factor of galloping of iced-conductor, but the result of theoretically analysis and numerical simulation isn’t suited for the requirement of transmission line project. In the paper, basing on the theoretically analysis and numerical simulation, the simulation tests in wind tunnel of crescent-shaped iced conductor is stetted up and put into practice, and then the systemic study is carried into execution. The result of research is indicated that there is a better coherence between the numerical simulation and experiment test, and the result of numerical simulation is the beneficial supplement to the experiment test. The result can not only provide the original date for the galloping analysis, but also validate the affectivity of numerical simulation, support the research of mechanism and control of galloping.

Abstract: In order to understand the influencing factors and laws on the ultrasonic cavitation dynamics in chitosan solution, numerical simulation of cavitation bubble motion had been performed based on Rayleigh-Plesset equation and the equation was solved by using 4~5 order Runge–Kutta algorithm. By numerical simulation the effects of frequency and intensity of ultrasonic, ambient pressure, initial bubble radius, concentration and temperature of solution, dual-frequency ultrasonic on the motion of cavitation bubble were discussed. The results show that for improving the effect of cavitation in chitosan solution, ultrasonic cavitation should be under the conditions of lower frequency, lower intensity, lower ambient pressure, smaller initial cavitation bubble, moderate temperature of solution and lower concentration. It is also found that the cavitation intensity due to dual-frequency ultrasonic is stronger than that of single-frequency ultrasonic.

Abstract: In order to understand the particle velocity distribution characteristics of the 2D bubbling fluidized bed. The paper study that several mainly factors (static bed height, particle size and gas speed) influence on velocity distribution of the outer particles by experiment. The results for particles around bubble show that: ①Under the condition of the same static bed height and particle size, the particle velocity increases with the gas speed; the particle velocity increase at the axial direction and has no rule at radial direction. ②On the basis of the same wind speed and particle size, the particle velocity reduce with the static bed height; the particle velocity decreases at the axial direction and has no regular at radial direction. ③At the same wind speed and static bed height, the particle velocity is gradual reducing with the particle size; the particle velocity also reduce at the axial direction and has no rule at radial direction.