Sloshing waves in a heated viscoelastic fluid layer in an excited rectangular tank

In this paper, we have investigated the motion of a heated viscoelastic fluid layer in a rectangular tank that is subjected to a horizontal periodic oscillation. The mathematical model of the current problem is communicated with the linearized Navier–Stokes equation of the viscoelastic fluid and heat equation together with the boundary conditions that are solved by means of Laplace transform. Time domain solutions are consequently computed by using Durbin's numerical inverse Laplace transform scheme. Various numerical results are provided and thereby illustrated graphically to show the effects of the physical parameters on the free-surface elevation time histories and heat distribution. The numerical applications revealed that increasing the Reynolds number as well as the relaxation time parameter leads to a wider range of variation of the free-surface elevation, especially for the short time history.     

热对流条件下颗粒沉降的格子Boltzmann方法模拟

采用格子Boltzmann方法模拟了在热对流条件下的颗粒沉降问题, 在研究单颗粒在等温流体、热流体和冷流体中运动的基础上, 进一步模拟了两个不同温度的颗粒在流体中的沉降.结果表明:两等温颗粒的沉降方式与雷诺数Re以及格拉晓夫数Gr密切相关, 而两不同温度的颗粒与两等温颗粒的沉降规律有显著不同.无论初始位置如何, 冷颗粒最终总位于热颗粒下方运动, Re较大时, 发生连续的拖曳、接触现象, 而Re较小时, 冷颗粒会以较大的沉降速度远离热颗粒. 关键词： 格子Boltzmann方法 颗粒沉降 热对流     

Concurrent Detection of Protein Adsorption on Mixed Nanoparticles by Differential Centrifugal Sedimentation

In mixtures of nanoparticles of various sizes or compositions, monitoring protein partitioning on their surfaces provides important information about particle–protein interactions during competitive adsorption. Utilizing the size‐resolving capability of differential centrifugal sedimentation, the adsorption of bovine serum albumin on multisize gold nanoparticles with diameters ranging from 20 to 100 nm or gold, silver, and silica nanoparticles with similar diameter can be concurrently observed. This method can be used to gain insight into nanoparticle–protein interactions based on analyses of curvature and relative abundance.     

Modelling of change of the classifier separation characteristics by water injection into the apparatus

The investigation of the influence of additional water injection in a classifier on the particle separation process characteristics has been performed on the basis of numerical modelling. It has been shown that the increase in water injection velocity leads to the increase of both the cut size and the minimal value of separation curve. The change of the injector opening size influences only the minimum value of the separation function not altering the cut size at the specified water injection velocity.     

Nonlinear water wave interaction with floating bodies in SPH

A weakly compressible SPH solver is presented for applications involving nonlinear interaction between water waves and floating bodies. A complete algorithm able to compute fully coupled viscous Fluid–Solid interactions is described. No slip boundary condition on the solid surface is enforced through a ghost–fluid technique and the global loads are evaluated through the momentum exchange between fluid and ghost particles. A dedicated algorithm is developed to manage the intersection between the free surface and the solid profile. An explicit synchronous algorithm is proposed for the full coupling between fluid and rigid bodies. Stability, convergence and conservation properties are tested on several freely floating test cases and a final validation of the full algorithm is performed for the interaction between a 2-D box and a wave packet.     

微重力下低温贮箱压力控制技术进展

针对微重力下低温贮箱压力升高的问题,简要介绍了几种常用的低温贮箱压力控制的方法及原理,讨论了它们各自存在的问题,并简要展望未来低温贮箱压力控制技术的发展方向。文章指出,未来研究重点在于将主动制冷与被动绝热相结合,实现零蒸发贮存的热转移技术。     

相互碰撞的圆粒子在竖直通道中沉降的数值研究

采用格子Boltzmann方法,数值模拟了考虑相互碰撞的两圆粒子的沉降,分析了Re数、初始相对位移及通道宽度对粒子沉降的影响．结果表明,在0.1＜Re＜20范围内, 粒子沉降具有周期性．Re数越大,两圆粒子的相互作用越强,粒子横向位移的幅度也越大．在大Re数时,沉降的过程是两个粒子交替领先;在较小Re数时,当后面的粒子接近的时候,领先的粒子被向右侧推了一段后仍会继续领先;对中等Re数,原先在后面的粒子在第一次加速后将取得领先位置并一直保持下去．粒子的初始分布位置对沉降的形态影响不大．管道宽度变化时,粒子总的沉降特性不变,而周期改变,管道越宽,周期越长．     

带弹性附件充液矩形贮箱俯仰运动动态响应

首先建立了俯仰运动矩形贮箱刚-液-弹耦合系统在外力矩作用下的耦合动力学模型,给出满足边界条件的速度势函数和液面波高的级数表达式,采用伽辽金法离散,将动力学模型转化为常微分方程组,得到刚-液-弹耦合系统的固有频率,给出简单的近似表达式,分析了转动中心距静液面不同位置时刚-液-弹耦合系统各阶固有频率的变化规律,系统转动中心距静液面较近时,耦合后液体反对称模态和刚体的固有频率对比耦合前减小,较远时则增大,最后进行数值验证,比较分析了液体和弹性体对刚体姿态的影响．