CFD Analysis of Flow Patterns and Micromixing Efficiency in a Y-Type Microchannel Reactor

Aerodynamic experimentation and investigation of rotating blades has pioneered the research necessary for innovative lawnmower design. In this study, Computational Fluid Dynamics (CFD) models are generated for single and triple-blade arrangements to analyze their flow patterns and behavior. For the 2-D CFD analysis, blade profiles at several arbitrary radial sections have been selected for flow computations around the blade model. Likewise, the 3-D CFD analysis effectively simulates the flow patterns inside the entire triple-blade mower deck, as well as in single-blade enclosures. The accuracy of the attained CFD solutions was determined through comparison with experimental data. The flow behaviors were observed using both Laser Doppler Velocimetry (LDV) and a high-speed video camera recording at 2000 frames per second. Strain gage and pressure transducer analysis also aided in the correlative effort. It has been observed that both the mower deck configuration and blade profile share equal significance in the resultant flow profiles.

Download Full-text

In vitro PIV measurement and CFD analysis of flow patterns in cerebral aneurysm

Journal of the Visualization Society of Japan ◽

10.3154/jvs.24.supplement1_149 ◽

2004 ◽

Vol 24 (Supplement1) ◽

pp. 149-152

Author(s):

Koichi NISHINO ◽

Daisuke KAWAGUCHI ◽

Hidetaka SATO ◽

Haruo ISODA ◽

Takashi KOSUGI

Keyword(s):

Cerebral Aneurysm ◽

Flow Patterns ◽

Cfd Analysis ◽

Piv Measurement

Download Full-text

Numerical Analysis of Design and Off-Design Performance of High Specific Speed Mixed Flow Pumps

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

10.1115/ajk2011-06051 ◽

2011 ◽

Author(s):

Yumiko Sekino ◽

Yoichi Tanabe

Keyword(s):

Steady Flow ◽

Periodic Boundary ◽

Flow Analysis ◽

Flow Patterns ◽

Design Flow ◽

Cfd Analysis ◽

Mixed Flow ◽

Blade Passage ◽

Specific Speed ◽

Flow Pump

In most cases of high specific speed mixed flow pump applications, it is necessary to control off-design performance such as shutoff power/head and unstable characteristic as well as design point performance. The authors have been working on multi-objective optimization strategy of mixed flow pump design considering off-deign performance by means of Computational Fluid Dynamics (CFD). In the design optimization process, it was found that the steady CFD analysis using one pitch blade passage adopting periodic boundary condition could be used for relative comparison of the important performance characteristics such as the level of efficiency, the shutoff performance and the stall characteristics of different designs. However, the steady CFD analysis with one pitch blade passage showed that absolute values of head and shaft power were estimated lower than those of the experimental results especially in the partial capacity range. In order to improve the accuracy of CFD results it should be necessary to use full pitch model. In this paper, the evaluation results of three CFD approaches on the capability of the performance prediction of the mixed flow pumps will be shown. The approaches evaluated are steady flow analysis with one pitch blade passage using periodic boundary conditions, full pitch steady flow analysis and unsteady flow analysis. It was found from the evaluation results that the full pitch steady flow analysis showed the same tendency as one pitch analysis and the unsteady CFD provided higher accuracy of the shutoff head. However, the steady analysis should still be useful to reduce the high computational cost and the amount of time. Meanwhile the unsteady analysis clarifies the details of the off-design flow patterns. The effects of the turbulence models and the details of the off-design flow patterns were also discussed in this paper.

Download Full-text

F-0814 CFD Analysis of Diastolic Flow Patterns by the use of a Three-Dimensional Model of the Left Ventricle

The proceedings of the JSME annual meeting ◽

10.1299/jsmemecjo.iv.01.1.0_27 ◽

2001 ◽

Vol IV.01.1 (0) ◽

pp. 27-28

Author(s):

Masanori Nakamura ◽

Shigeo Wada ◽

Taisei Mikami ◽

Akira Kitabatake ◽

Takeshi Karino

Keyword(s):

Left Ventricle ◽

Three Dimensional ◽

Flow Patterns ◽

Cfd Analysis ◽

Dimensional Model ◽

Three Dimensional Model ◽

Diastolic Flow

Download Full-text

PREDICTION OF COMPLEX FLOW PATTERNS IN INTRACRANIAL ATHEROSCLEROTIC DISEASE USING COMPUTATIONAL FLUID DYNAMICS

Neurosurgery ◽

10.1227/01.neu.0000298914.32248.dc ◽

2007 ◽

Vol 61 (4) ◽

pp. 842-852 ◽

Cited By ~ 26

Author(s):

Clemens M. Schirmer ◽

Adel M. Malek

Keyword(s):

Dynamic Properties ◽

Fluid Dynamic ◽

Three Dimensional ◽

Flow Patterns ◽

Atherosclerotic Disease ◽

High Shear ◽

Cfd Analysis ◽

Stent Angioplasty ◽

Complex Flow ◽

Intracranial Atherosclerotic Disease

Abstract OBJECTIVE Although carotid and vertebral intracranial atherosclerotic disease (ICAD) can lead to both hemodynamic insufficiency and thromboembolism, its fluid dynamic properties remain undefined because of its intricate features and complex three-dimensional geometry. We used computational fluid dynamic (CFD) analysis to model the hemodynamics of symptomatic ICAD lesions. METHODS Nine ICAD lesions (six carotid, two vertebral, one middle cerebral) underwent high-resolution catheter-based digital rotational angiography. The reconstructed three-dimensional volumes of the target lesions were segmented and used to generate hybrid computational meshes. Dynamic pulsatile CFD analysis was performed using a non-Newtonian shear-dependent model of blood's viscosity. RESULTS CFD results revealed complex flow patterns within ICAD lesions with midstenotic shear rates of greater than 19,000/s, sufficiently high to induce high-shear platelet activation. Vorticity and helicity within the stenoses were followed by sudden deceleration with formation of vortex cores. Pressure gradients were significant mostly at greater than 75% stenosis with a mean time-averaged drop of 27.2 ±17.8 mmHg. Unlike the smoothly-varying helicity imparted by the three-dimensional anatomy of the intracranial circulation, poststenotic regions of ICAD lesions showed significant and rapidly fluctuating helicity and vorticity patterns, which may contribute to the propagation of platelets activated by the high shear region within the stenosis throat. Stent angioplasty restored the hemodynamic profile of ICAD lesions to within contralateral controls. CONCLUSION Patient-based symptomatic ICAD lesions studied using CFD analysis appear to harbor a hemodynamically pathological environment that favors the activation, aggregation and distal embolization of platelets and is reversed by endovascular stent angioplasty.

Download Full-text

First- and second-hand smoke dispersion analysis from e-cigarettes using a computer-simulated person with a respiratory tract model

Indoor and Built Environment ◽

10.1177/1420326x17694476 ◽

2017 ◽

Vol 27 (7) ◽

pp. 898-916 ◽

Cited By ~ 11

Author(s):

Kazuki Kuga ◽

Kazuhide Ito ◽

Sung-Jun Yoo ◽

Wenhao Chen ◽

Ping Wang ◽

...

Keyword(s):

Respiratory Tract ◽

Cfd Simulation ◽

Electronic Cigarettes ◽

Inhalation Exposure ◽

Vapour Phase ◽

Flow Patterns ◽

Second Hand Smoke ◽

Deposition Flux ◽

Cfd Analysis ◽

Human Respiratory Tract

The purpose of this study was to investigate, in the human respiratory tract, the flow patterns and adsorption flux (deposition flux) distributions of volatile organic compounds (VOCs) generated by the use of electronic cigarettes (e-cigarettes) through the application of a three-dimensional computational fluid dynamics (CFD) analysis. Two types of human respiratory tract models, which give detailed respiratory tract geometries were reproduced in this study using computed tomography data, for the CFD analysis of inhalation exposure. Complicated flow patterns, nonuniform distributions of VOC concentrations, and heterogeneous adsorption flux distributions were determined within the human respiratory tract models, and individual specificity was confirmed. The CFD simulation results of adsorption flux distributions on the epithelium tissue surfaces of airways denoted the probability distributions of inhalation exposure in respiratory tracts, and high adsorption flux sites representing ‘hot spots’ were delineated for tissue doses of VOCs generated from smoking e-cigarettes. Furthermore, dispersion and diffusion of VOCs in an indoor environment due to exhalation of the vapour phase of e-cigarette emissions were analysed by using a computer-simulated person with a numerical respiratory tract model through an integrated and contiguous analysis of inhalation and exhalation modes during e-cigarette smoking.

Download Full-text