scholarly journals The proposal and realization on more exact modeling of COIL performance

2013 ◽  
Vol 1 (1) ◽  
pp. 50-59
Author(s):  
Shouxian Li ◽  
Xiaojian Shu ◽  
Yanyi Du ◽  
Hua Su ◽  
Yan Li ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Flow Field ◽  
Optical Fibers ◽  
High Power ◽  
Large Scale ◽  
Radiation Transport ◽  
Beam Quality ◽  
Three Dimensional ◽  
Computational Effort ◽  
Atmospheric Propagation

AbstractThe chemical oxygen–iodine laser (COIL) is the shortest-wavelength high-power chemical laser that has been demonstrated. The characteristics, such as good atmospheric propagation, short wavelength and excellent transmission through optical fibers, make the COIL a good candidate for high-power laser application. To model the complete COIL lasing interaction, a three-dimensional formulation of the fluid dynamics, species continuity and radiation transport equations is necessary. The computational effort to calculate the flow field over the entire nozzle bank with a grid fine enough to resolve the injection holes is so large as to preclude doing the calculation. The approach to modeling chemical lasers then has been to reduce the complexity of the model to correspond to the available computational capability, adding details as computing power increased. The modeling of lasing in the COIL medium is proposed, which is coupling with the effects induced by transverse injection of secondary gases, non-equilibrium chemical reactions, nozzle tail flow and boundary layer. The coupled steady solutions of the fluid dynamics and optics in a COIL complex three-dimensional cavity flow field are obtained following the proposal. The modeling results show that these effects have some influence on the lasing properties. A feasible methodology and a theoretical tool are offered to predict the beam quality for large-scale COIL devices.

scholarly journals Large-Scale Flow in Micro Electrokinetic Turbulent Mixer

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 813 ◽  
Author(s):  
Keyi Nan ◽  
Zhongyan Hu ◽  
Wei Zhao ◽  
Kaige Wang ◽  
Jintao Bai ◽  
...  
Keyword(s):  
Flow Field ◽  
Electric Conductivity ◽  
Large Scale ◽  
Three Dimensional ◽  
Mixing Process ◽  
Mean Flow ◽  
Velocity Fluctuations ◽  
Two Fluids ◽  
Large Scale Flow ◽  
Particle Imaging

In the present work, we studied the three-dimensional (3D) mean flow field in a micro electrokinetic (μEK) turbulence based micromixer by micro particle imaging velocimetry (μPIV) with stereoscopic method. A large-scale solenoid-type 3D mean flow field has been observed. The extraordinarily fast mixing process of the μEK turbulent mixer can be primarily attributed to two steps. First, under the strong velocity fluctuations generated by μEK mechanism, the two fluids with different conductivity are highly mixed near the entrance, primarily at the low electric conductivity sides and bias to the bottom wall. Then, the well-mixed fluid in the local region convects to the rest regions of the micromixer by the large-scale solenoid-type 3D mean flow. The mechanism of the large-scale 3D mean flow could be attributed to the unbalanced electroosmotic flows (EOFs) due to the high and low electric conductivity on both the bottom and top surface.

scholarly journals RV instantaneous intraventricular diastolic pressure and velocity distributions in normal and volume overload awake dog disease models

2003 ◽  
Vol 285 (5) ◽  
pp. H1956-H1965 ◽  
Author(s):  
Ares Pasipoularides ◽  
Ming Shu ◽  
Ashish Shah ◽  
Alessandro Tucconi ◽  
Donald D. Glower
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Diastolic Pressure ◽  
Dynamic Pressure ◽  
Three Dimensional ◽  
Pressure Rise ◽  
Volume Overload ◽  
Spatiotemporal Resolution ◽  
Intraventricular Flow ◽  
Normal Wall

Intraventricular diastolic right ventricular (RV) flow field dynamics were studied by functional imaging using three-dimensional (3D) real-time echocardiography with sonomicrometry and computational fluid dynamics in seven awake dogs at control with normal wall motion (NWM) and RV volume overload with diastolic paradoxical septal motion. Burgeoning flow cross section between inflow anulus and chamber walls induces a convective pressure rise, which represents a “convective deceleration load” (CDL). High spatiotemporal resolution dynamic pressure and velocity distributions of the intraventricular RV flow field revealed time-dependent, subtle interactions between intraventricular local acceleration and convective pressure gradients. During the E-wave upstroke, the total pressure gradient along intraventricular flow is the algebraic sum of a pressure decrease contributed by local acceleration and a pressure rise contributed by a convective deceleration that partially counterbalances the local acceleration gradient. This underlies the smallness of early diastolic intraventricular gradients. At peak volumetric inflow, local acceleration vanishes and the total adverse intraventricular gradient is convective. During the E-wave downstroke, the strongly adverse gradient embodies the streamwise pressure augmentations from both local and convective decelerations. It induces flow separation and large-scale vortical motions, stronger in NWM. Their dynamic corollaries on intraventricular pressure and velocity distributions were ascertained. In the NWM pattern, the strong ring-like vortex surrounding the central core encroaches on the area available for flow toward the apex. This results in higher linear velocities later in the downstroke of the E wave than at peak inflow rate. The augmentation of CDL by ventriculoannular disproportion may contribute to E wave and E-to-A ratio depression with chamber dilatation.

scholarly journals Assessment of the Flow Field in the HeartMate 3 Using Three-Dimensional Particle Tracking Velocimetry and Comparison to Computational Fluid Dynamics

ASAIO Journal ◽  
2020 ◽  
Vol 66 (2) ◽  
pp. 173-182 ◽  
Author(s):  
Bente Thamsen ◽  
Utku Gülan ◽  
Lena Wiegmann ◽  
Christian Loosli ◽  
Marianne Schmid Daners ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Particle Tracking ◽  
Particle Tracking Velocimetry ◽  
Three Dimensional

scholarly journals NUMERICAL SIMULATION OF THREE-DIMENSIONAL FLOW AROUND HARBOR DUE TO TSUNAMI USING FAVOR METHOD AND WENO SCHEME

2018 ◽  
pp. 71
Author(s):  
Yuki Kajikawa ◽  
Masamitsu Kuroiwa ◽  
Naohiro Otani
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Three Dimensional ◽  
Weno Scheme ◽  
Scale Model ◽  
Governing Equations ◽  
3D Flow ◽  
Complex Boundaries ◽  
Cartesian Coordinate ◽  
Fifth Order

In this paper, a three-dimensional (3D) tsunami flow model was proposed in order to predict a 3D flow field around a harbor accurately when tsunami strikes. In the proposed numerical model, the Cartesian coordinate system was adopted, and the Fractional Area/Volume Obstacle Representation (FAVOR) method, which has the ability to impose boundary conditions smoothly at complex boundaries, was introduced into the governing equations in consideration of applying the estimation to actual harbors with complex shape in the future. Moreover, the fifth-order Weighted Essentially Non- Oscillatory (WENO) scheme, which is a technique for achieving high accuracy even if the calculation mesh is coarse, was applied to discretization of the convection terms of the governing equations. In order to verify the validity of the model, it was applied to a large-scale laboratory experiment with a scale model of harbor. Comparisons between the simulated and experimental results showed that the model was able to reproduce the time variation of the flow field with sufficient accuracy. Moreover, the simulated results showed that a complex 3D flow field with some vertical vortex flows was generated around a harbor when tsunami struck.

scholarly journals Laser generated Richtmyer–Meshkov instability and nonlinear wave paradigm in turbulent mixing: I. Central region of Gaussian spot

2016 ◽  
Vol 34 (4) ◽  
pp. 687-704 ◽  
Author(s):  
Stjepan Lugomer
Keyword(s):  
Flow Field ◽  
Turbulent Mixing ◽  
Large Scale ◽  
Pressure Field ◽  
Three Dimensional ◽  
Target Surface ◽  
Kp Equation ◽  
New Paradigm ◽  
Shape Oscillations ◽  
The Individual

AbstractA three-dimensional Richtmyer–Meshkov instability (RMI) was generated on metal target by the laser pulse of Gaussian-like power profile in the semiconfined configuration (SCC). The SCC enables the extended lifetime of a hot vapor/plasma plume above the target surface as well as the fast multiple reshocks. The oscillatory pressure field of the reshocks causes strong bubble shape oscillations giving rise to the complex wave-vortex phenomena. The irregularity of the pressure field causes distortion of the shock wave front observed as deformed waves. In a random flow field the waves solidified around the bubbles form the broken “egg-karton” structure – or the large-scale chaotic web. In the coherent flow field the shape oscillations and collapse of the large bubbles generate nonlinear waves as the line- and the horseshoe-solitons. The line solitons are organized into a polygonal web, while the horseshoe solitons make either the rosette-like web or appear as the individual parabolic-like solitons. The configurations of the line solitons are juxtapositioned with solitons simulated by the Kadomtsev–Petviashvili (KP) equation. For the horseshoe solitons it was mentioned that it can be obtained by the simulation based on the cylindrical KP equation. The line and the horseshoe solitons represent the wave-vortex phenomena in which the fluid accelerated by the shock and exposed to a subsequent series of fast reshocks follows more complex scenario than in the open configuration. The RMI environment in the SCC generates complex fluid dynamics and the new paradigm of wave vortex phenomena in turbulent mixing.

Optimze the Structure of Impeller for Stirred Bioreactor

2013 ◽  
Vol 694-697 ◽  
pp. 148-153 ◽  
Author(s):  
Li Kuan Zhu ◽  
Bo Yan Song ◽  
Zhen Long Wang ◽  
Yu Kui Wang
Keyword(s):  
Fluid Dynamics ◽  
Flow Field ◽  
Shear Force ◽  
Large Scale ◽  
Cfd Simulation ◽  
Simulation Method ◽  
Stirred Bioreactor ◽  
Anticlockwise Rotation ◽  
Computational Fluid Dynamics Cfd ◽  
Large Scale Culture

This paper mainly makes comparative analysis on four main types of blade in stirred bioreactor by Computational Fluid Dynamics(CFD) simulation. Firstly we establish simulation method suited for stirred bioreactor, then simulate the velocity and shear force of flow field in the bioreactor. No matter from flow field mixing or shear force aspect, Elephant Ear blades is the most suitable for cell large scale culture. At last, it optimizes the installation method and angle of Elephant Ear blades. It concludes that anticlockwise rotation and 45°installation angle is the optimum.

Analysis of a LPT Rotor Blade for a Geared Engine: Part II — Characterization of the Time-Varying Flow Field in a Single Stage Research Turbine

2016 ◽  
Author(s):  
Daniele Infantino ◽  
Francesca Satta ◽  
Daniele Simoni ◽  
Marina Ubaldi ◽  
Pietro Zunino ◽  
...  
Keyword(s):  
Flow Field ◽  
Rotor Blade ◽  
Large Scale ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Single Stage ◽  
Tip Vortex ◽  
Time Dependent ◽  
Exit Plane ◽  
Open Rotor

The present paper is the second part of a two-part paper focused on the design and the analysis of an optimized rotor blade for a geared open rotor engine. This part is focused on the experimental investigation of the three-dimensional unsteady flow field at the exit plane of a rotor row installed in a large scale single-stage low speed research turbine. The investigation is aimed at in depth characterizing the wake-boundary layer and the vortex-vortex interaction processes induced by the rotor-stator relative motion. Measurements have been carried out at a typical aeroengine cruise condition Reynolds number. The rotor blade aerodynamic loadings at different blade spans have been measured. A five-hole probe has been used to assess the row efficiency and detailed hot-wire phase-locked ensemble-averaged data have been analyzed to characterize the three-dimensional time-dependent flow field at the rotor exit plane. Results clearly highlight a significant distortion of the rotor blade wake and tip vortex during the migration of the high turbulence regions (wake and secondary flows) associated with the upstream stator. The unsteady interaction between the stator secondary flows and the rotor passage vortex provokes a time dependent movement of the low momentum area at the hub surface, sensibly modifying the penetration of the rotor secondary flows in an incoming stator wake passage period. The comparison of deterministic and random velocity fluctuations also allows the distinction between the structures generated by the stator and those due to the rotor.

scholarly journals Proposed wavelength measurements of silicon X-ray spectra: Application to Vela X-1

2008 ◽  
Vol 86 (1) ◽  
pp. 183-189 ◽  
Author(s):  
D A Liedahl ◽  
G V Brown
Keyword(s):  
Neutron Star ◽  
Stellar Wind ◽  
Large Scale ◽  
Radiation Transport ◽  
Three Dimensional ◽  
Mass Transfer Process ◽  
Gravitational Potential Energy ◽  
X Ray ◽  
Close Orbit ◽  
Mass Capture

When a stellar wind from a massive star is captured by a neutron star in close orbit, gravitational potential energy is converted into hard X-radiation near the surface of the neutron star. The X-radiation, in turn, modifies the wind through heating and photoionization, which affects the dynamics of mass capture. We have begun a project to further elucidate this process, which involves time-dependent three-dimensional hydrodynamics, large-scale atomic physics calculations, and radiation transport, integrated in an attempt to derive a self-consistent “first principles” description of the mass transfer process. We anticipate that the high-resolution silicon X-ray spectrum, produced by innershell photoionization and photoexcitation, as measured by the Chandra observatory, will provide benchmarks for these calculations. However, theoretical wavelengths, which are required in order to draw inferences concerning the velocity field of the wind, are uncertain at the level of the likely Doppler shifts in the stellar wind. EBIT measurements could lead to a reliable set of wavelengths, thereby providing observational constraints on the physics that powers some of the brightest X-ray sources in the Galaxy. PACS Nos.: 32.30.Rj, 32.80.Fb, 32.80.Hd, 52.25.Os, 52.72.+v, 97.10.Me, 97.80.Jp

INNER FLOW FIELD OF POOL MIXED BY THREE SUBMERSIBLE MIXERS

2012 ◽  
Vol 11 (02) ◽  
pp. 91-97 ◽  
Author(s):  
FEI TIAN ◽  
WEIDONG SHI ◽  
HUA JIANG
Keyword(s):  
Flow Field ◽  
Average Velocity ◽  
Large Scale ◽  
Sewage Treatment ◽  
Three Dimensional ◽  
Engineering Application ◽  
Circulating Water ◽  
Three Dimensional Modeling ◽  
Dimensional Modeling ◽  
Practical Engineering

To study the agitating effect of submersible mixers in a square sewage treatment pool, the three-dimensional modeling Pro/E software was adopted to establish the physical model. The large-scale computational fluid dynamics software FLUENT6.3 was used, and the large-scale software ICEM was selected to build an unstructured tetrahedron grid of the sewage treatment pool. Next, the sewage treatment pool was numerically simulated by RNG k-ε turbulent model and move coordinate system technology. The macrofluid field and the flow field distribution of each section were analyzed to observe the efficiency of each submersible mixer. The average velocity of the fluid and the stirring volume were studied simultaneously. Results show that, under the action of three mixers, fluid of the sewage pool forms a continuous circulating water flow. The fluid is mixed adequately. The average velocity of fluid in the pool is at around 0.3 m/s, and the fluid mixing area in the pool is more than 90%, which is in agreement with the working requirements. Consequently, it can provide a reference basis for the practical engineering application of submersible mixers by using this method.

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