Vortex dislocation in wake-type flow caused by local spanwise nonuniformity

DNS of spatiotemporal evolution of a wake-type flow is performed. In the incoming flow, a local spanwise nonuniformity in momentum defect is initially imposed. Results show that the spanwise nonuniformity leads to a series of symmetric twist vortex dislocation in downstream of the flow. Vortex line variations and substantial transition of vorticity from spanwise to the streamwise and vertical directions clearly feature the generation of a vortex dislocation and the real vortex linking in the dislocation. Dynamical process and the mechanism responsible for the vortex dislocation are described.

Numerical Research on Liquid Spray in Supersonic Cross Flow

Numerical simulation was conducted to characterize the kerosene spray injecting into supersonic cross flow, especially focusing on the aerodynamic secondary breakup effect of the supersonic cross flow on the initial droplets. It was revealed that the initial parent drops were broken up into small drops whose diameter is about O(10) micrometers soon after they entered into the supersonic cross flow. During the appropriate range of initial drop size, the parent droplets would be broken up into small drops with the same magnitude diameter no matter how large the initial drops SMD was.

Study of Interaction Force between Antigen and Antibody Using Flow Chamber Method

A parallel plate flow chamber was used to study the interaction force between human IgG (immobilized on a chip surface as ligand) and goat anti-human IgG (immobilized on microspheres surface as receptor). First, it was demonstrated that the binding force between the microspheres and the chip surface came from the bio-specific interaction between the antigen and the antibody. Secondly, it was obtained that the critical shear rate to detach microspheres from the chip surface increases with the ligand surface concentration. Finally, two models to estimate the antigen-antibody bond strength considering bonds' positions were proposed and analyzed.

Characteristics of Wake Flow in Long Bluff Bodies

Vortex shedding is the main characteristics of bluff bodies, which will cause the bluff bodies to vibrate and sometimes result in the structures failure. In this paper the wake flow characteristics of 21 bluff bodies with rectangular, rounded and angular profiles and the length-to-width ratio in the range of 4~12 were deeply studied by Micro ADV. Two parameters, namely the relative intensity of the load due to Karman vortices and the large scale vortex intensity, were introduced to measure the wake flow intensity. Generally, the values of these parameters for different bluff bodies are consistent with each other. The experiment results showed that the key factor affecting the wake flow characteristics is the bluff edge, especially the leading edge geometry. The wake flow in bluff bodies with rounded edge profiles has more regular vortices and becomes more periodic than that in bluff bodies with rectangular ones. A bluff body with angular edged profile was witnessed to have not only small wake loading but small hydraulic resistance also.

Serrated Plastic Flow During Nanoindentation in Nd-Based Bulk Metallic Glasses

The microstructure of Nd_{60}Al_{10}Ni_{10}Cu_{20-x}Fex (x = 0, 5, 7, 10, 15, 20) alloys can change from homogeneous phase to a composite structure consisting of amorphous phase plus clusters or nanocrystals by adjusting the Fe content. The effect of microstructure on the plastic deformation behavior in this alloy system is studied by using nanoindentation. The alloys with homogeneous amorphous structure exhibit pronounced flow serrations during the loading process of nanoindentation. The addition of Fe changes the plastic deformation behavior remarkablely. No flow serration is observed in the alloys with high Fe content for the indentation depth of 500 nm. The mechanism for the change of plastic serrated flow behavior is discussed.

Effect of Pipe Diameter on Flow Pattern Transition in Vertical Oil Water Flows

This paper investiges the effect of pipe diameter on flow pattern transition boundary in oil water vertical flows, and proposes a model to determine the maximum inner diameter (D_{infty s}) of a pipe in which the slug flow would not occur When pipe inner diameter D>D_{infty s}, only bubble flow exists, while D