Longitudinal Vibration of Variable Cross-Sectional Nanorods

Vibration problem of variable cross-sectional nanorods have been investigated. Analytical solutions have been determined for the variable cross-sectional nanorods for a family of cross-sectional variation. Cross-sectional area variation has been assumed as power function of the axial coordinate. Nonlocal governing equation of motion has been obtained as a second order linear differential equation. Bessel functions have been used in analytical solution of the governing differential equation. Effect of nonlocal and area variation power parameters on dynamics of nanorods have been analyzed. Mode shapes of nanorod have been depicted in various cases and boundary conditions. Present results could be useful at design of atomic force microscope’s probe tip selection.

Thermohydraulic modeling in transient state for evaluation of pipeline shutdown and restart procedures

In order to study shutdown and re-start in heavy crude oil pipelines, a model was developed. It simulates, in a transient state, the behavior of pressure, flow and temperature variables, averaged over the cross-sectional area and as a function of time and the axial coordinate. The model was validated with actual operational data from a test case. Results obtained for different operating points, stopping time, crude properties, topographies and lengths are presented. Additionally, the governing equations are converted to dimensionless expressions in order to obtain the dimensionless numbers relevant to the re-start operation for crude oil pipelines.

Experimental Investigation of the Swirl Development at the Inlet of a Coaxial Rotating Diffuser or Nozzle

When a fluid enters a rotating pipe, a swirl boundary layer with thickness of δ̃S appears at the wall and interacts with the axial momentum boundary layer with thickness of δ̃. The swirl is produced by the wall shear stress and not due to kinematic reasons as by a turbomachine. In the center of the pipe, the fluid is swirl-free and is accelerated due to axial boundary layer growth. Below a critical flow number φ < φc, there is flow separation, known in the turbomachinery context as part load recirculation. The previous work analyzes the flow at the inlet of a coaxial rotating circular pipe (R̃=R̃0). For a systematic approach to a turbomachine, the influence of the turbine's and pump's function, schematically fulfilled by a diffuser and a nozzle, on the evolution of the swirl and flow separation is to analyze. The radius of the rotating pipe depends linearly on the axial coordinate, yielding a rotating circular diffuser or nozzle. The swirl evolution depends on the Reynolds number, flow number, axial coordinate, and apex angle. The influence of the latter is the paper's main task. The circumferential velocity component is measured applying one-dimensional laser Doppler anemometry (LDA) to investigate the swirl evolution.

MIXED CORE SUBCHANNEL MODEL FOR SUBCAL AND COUPLING WITH ANDREA

This paper presents the results of an analysis of flow distribution in VVER-1000 mixed core consisting of fuel assemblies with non-identical spacing grids. The calculation was carried out using the modified subchannel code SUBCAL-AZ which allows to calculate 3D thermal-hydraulic characteristics of the coolant flow in the full core subchannel model coupled with the neutron-physical code ANDREA. This full core subchannel model was created in three variants depending on the ANDREA calculations. The first variant (homogeneous core) consisted of 163 hydraulically identical fuel assemblies TVSA-T mod.2, whereas the other variants (mixed cores) consisted of fuel assemblies TVSA-T mod.0, mod.1 and mod.2. These fuel assemblies mainly differ in types, number and axial coordinate of spacing grids and also in diameter of guide tubes. The influence of mixed core to flow distribution was obtained by comparing these variants.

LATERAL COOLANT FLOW BETWEEN FUEL ASSEMBLIES IN MIXED CORES

This paper presents the results of an analysis of lateral coolant flow between adjacent fuel assemblies with non-identical spacing grids in a mixed core consisting of TVSA-T mod.1 and TVSA-T mod.2 fuel assemblies. The calculation was carried out using modified subchannel code SUBCAL which allows to calculate 3D thermo-hydraulic characteristics of the coolant flow in the full three fuel assemblies model. This full three fuel assemblies model was created in two variants. The first variant consisted of three hydraulically identical fuel assemblies TVSA-T mod.1, whereas the second variant consisted of two fuel assemblies TVSA-T mod.1 and one fuel assembly TVSA-T mod.2 which mainly differ in types, number and axial coordinate of spacing grids and also in diameter of guide tubes. The influence of mixed core to lateral coolant flow and hence coolant temperature was obtained by comparing these two variants. The power distribution was taken from presumed mixed core fuel reload calculated by macro-code ANDREA. Finally there were also provided a comparison of results achieved by subchannel analysis approach with calculation of similar problem using CFD code ANSYS CFX by TVEL, the fuel supplier.

Slip Effects on Peristaltic Flow of Magnetohydrodynamics Second Grade Fluid Through a Flexible Channel With Heat/Mass Transfer

In the present framework, a model is constituted to explore the peristalsis of magnetohydrodynamics (MHD) viscoelastic (second grade) fluid with wall properties. The study is beneficial in understanding blood flow dynamics through microchannels. The mechanisms of heat and mass transfer are also modeled in the existence of viscous dissipation and Soret effects. The conducting second grade fluid is permeated by a vertical magnetic field. Perturbation technique is opted to present series solutions by assuming that the wavelength of the sinusoidal wave is small in comparison to the half-width of the channel. The solution profiles are computed and elucidated for a certain range of embedded parameters. Moreover, plots of heat transfer coefficient against the axial coordinate are also portrayed and deliberated. The main outcome of the current research is that both viscoelasticity and slip effect considerably alter the flow fields. Moreover, an increasing trend in solute concentration is anticipated for increasing the Soret effect strength.