An Analysis for Plane Strain Plastic Deformation in Metal-Working Process

1977 ◽  
Vol 99 (3) ◽  
pp. 727-732 ◽  
Author(s):  
Y. S. Lee ◽  
M. R. Patel
Keyword(s):  
Plane Strain ◽  
Plastic Flow ◽  
Fluid Dynamic ◽  
Constitutive Relations ◽  
Flow Equation ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Rate Behavior ◽  
Strain Equation ◽  
Strain Rate Behavior

The two-dimensional plane strain equation of large plastic flow, expressed in terms of the stream function gradients, is modified using complex variables. The resulting governing equation is solved analytically for a class of nonlinear materials whose stress-strain rate behavior can be expressed by σ¯ = ce¯˙m. A one-to-one correspondence between the plastic flow equation using the Levy-Mises constitutive relations and the Navier-Stokes equation of fluid flow with zero inertia term is established for constant λ˙. This correspondence allows the existing fluid dynamic solution to be used for the plasticity analysis. An analytical solution of plane strain extrusion of linear material through square-cornered die is presented to illustrate the procedure.

Computerized Fluid Dynamic Study of Parameter Effects on the Performance of Coaxial Propellers

2020 ◽  
Vol 17 (7) ◽  
pp. 3237-3242
Author(s):  
Young-Tae Kim ◽  
Chang Hwan Park ◽  
Hak Yoon Kim
Keyword(s):  
Pitch Angle ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Steady State Condition ◽  
Performance Variation ◽  
Air Vehicle ◽  
Program Star ◽  
And Control

The computerized fluid dynamic (CFD) analysis was performed for 1.8 m diameter coaxial propellers to be applied to the multi-copter type Personal Air Vehicle (PAV) having conceptually 600 kg of Maximum Take-Off Weight (MTOW). Methods/Statistical analysis: Using the commercial CFD program STAR-CCM+ (13.03.11), the coaxial propellers were analyzed at the same RPM under the steady state condition. The three-dimensional Compressible Reynolds Mean Navier-Stokes equation was applied and the Moving Reference Frame (MRF) technique was used. With the optimum single pitch angle of upper propeller, the lower propeller’s pitch was changed for the varying propeller spacing to identify the performance variation and the interference effect. The lower propeller has to be different pitch setting other than the upper propeller’s optimum pitch angle because of the interfered flow effect between propellers. The propeller spacing is not so sensitive to efficiency if the spacing is more than 0.25 of propeller diameter. Study shows that the identified pitches and spacing of coaxial propellers are essential for designing the configuration and control of multi-copter type PAV which uses variable pitch propellers for safety and efficiency.

Analytic Solution for Microscale Poiseuille Flow Based on Super-Burnett Equations

2013 ◽  
Vol 705 ◽  
pp. 609-615
Author(s):  
Cheng Qian Song ◽  
Xie Yuan Yin ◽  
Feng Hua Qin
Keyword(s):  
Poiseuille Flow ◽  
Constitutive Relations ◽  
Slip Boundary Condition ◽  
Continuous Model ◽  
Analytic Solutions ◽  
High Order ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Slip Boundary ◽  
The Difference

The previous studies show that the transverse distribution of pressure and temperature in microscale Poiseuille flow cannot be predicted by Navier-Stokes equation with the slip boundary condition. In this paper, we analyzed the planar microchannel force-driven Poiseuille flow by high order continuum model. The super-Burnett constitutive relations were used and the nonlinear ordinary differential Equations of higher-orders were obtained by the hypothesis of parallel flow. With a perturbations theory, we linearized the equations and obtained the analytic solutions. The results show that the solutions can capture the temperature dip which is the same as the DSMC result. However, we also find that the temperature profile near the wall does always not match with the DSMC result. Especially, the difference in the qualitative exists when the Knudsen number is large enough. The non-equilibrium effect near the wall such as Knudsen layer can not be described entirely by continuous model even with high order constitutive relations and this confines the extension of the continuous model such as super-Burnett one.

Computational Prediction of Hemolysis by Blade Flow Field of Micro-Axial Blood Pump

2006 ◽  
Author(s):  
Xin Chen ◽  
Jianping Tan
Keyword(s):  
Blood Flow ◽  
Flow Field ◽  
Fluid Dynamic ◽  
Computational Prediction ◽  
Blood Pump ◽  
Navier Stokes ◽  
Initial Attempt ◽  
Navier Stokes Equation ◽  
Blood Damage ◽  
Blood Pumps

By analyzing fluid dynamics of blood in an artificial blood pump and simulating the flow field structure and the flow performance of blood, the blood flow and the damages in the designed blood pump would be better understood. This paper describes computational fluid dynamic (CFD) used in predicting numerically the hemolysis of blade in micro-axial blood pumps. A numerical hydrodynamical model, based on the Navier-Stokes equation, was used to obtain the flow in a micro-axial blood pump. A time-dependent stress acting on blood particle is solved in this paper to explore the blood flow and damages in the micro-axial blood pump. An initial attempt is also made to predict the blood damage from these simulations.

Effect of dome size on flow dynamics in saccular aneurysms – A numerical study

2020 ◽  
Vol 14 (3) ◽  
pp. 7181-7190
Author(s):  
Sathvik Nayak H. S. ◽  
Nitesh Kumar ◽  
S. M. A. Khader ◽  
Raghuvir Pai
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Flow Dynamics ◽  
Arterial System ◽  
Navier Stokes ◽  
Hemodynamic Parameters ◽  
Navier Stokes Equation ◽  
Neck Size ◽  
Human Arteries ◽  
Velocity Pressure

Image-based Computational Fluid Dynamic (CFD) simulations of anatomical models of human arteries are gaining clinical relevance in present days. In this study, CFD is used to study flow behaviour and hemodynamic parameters in aneurysms, with a focus on the effect of geometric variations in the aneurysm models on the flow dynamics. A computational phantom was created using a 3D modelling software to mimic a spherical aneurysm. Hemodynamic parameters were obtained and compared with the available literature to validate. Further, flow dynamics is studied by varying the dome size of the aneurysm from 3.75 mm to 6.25 mm with an increment of 0.625 mm keeping the neck size constant. The aneurysm is assumed to be located at a bend in the arterial system. Computational analysis of the flow field is performed by using Navier – Stokes equation for laminar flow of incompressible, Newtonian fluid. Parameters such as velocity, pressure, wall shear stress (WSS), vortex structure are studied. It was observed that the location of the flow separation and WSS vary significantly with the geometry of the aneurysm. The reduction of WSS inside the aneurysm is higher at the larger dome sizes for constant neck size.

Three-Dimensional Laminar Wall Jet Flows

2009 ◽  
Author(s):  
Kofi K. Adane ◽  
Mark F. Tachie
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Navier Stokes ◽  
Jet Flows ◽  
Wall Jet ◽  
Navier Stokes Equation ◽  
Flow Geometry

The present article reports on both experimental and numerical study of three-dimensional laminar wall jet flows. The wall jet was created using a circular pipe of diameter 7 mm and flows into an open channel. The Reynolds numbers based on the pipe diameter and jet exit velocity were varied from 310 to 1300. A particle image velocimetry (PIV) was used to conduct detailed velocity measurements at various streamwise-transverse and streamwise-spanwise planes. A complete nonlinear incompressible Navier-Stokes equation was also solved using a co-located finite volume based in-house computational fluid dynamic (CFD) code. This code was used to compute the experimental flow geometry. From the PIV measurements and CFD results, velocities profiles and jet-half-widths were extracted at selected locations. It was observed that the numerical results are in reasonable agreement with the experimental data. The distributions of the velocities, jet-half-widths and visualisation of the secondary flows were used to provide insight into the characteristics of three-dimensional wall jet flows.

GRANULE HYDRODYNAMICS METHOD: A DISCRETE ELEMENT METHOD ON FLUID MOTIONS

2012 ◽  
Vol 09 (01) ◽  
pp. 1240023
Author(s):  
MIN YAN ◽  
JIANYE YIN ◽  
BAOPING SUN ◽  
XIAO MA
Keyword(s):  
Constitutive Relations ◽  
Fluid Motion ◽  
State Equation ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method ◽  
Movement System ◽  
Velocity Derivative

A granule hydrodynamics method is proposed in studying complex dynamic behavior of wind-blown movement system. Fluid in the wind-blown movement system is discretized into elastic fluid granules in a certain scale of time and space. It is considered that fluid motion is caused by fluid granules collision and fluid density difference (or pressure difference). Based on the essential properties of fluid, the constitutive relations of fluid granules are well established in the proposed granule hydrodynamics method, fluid state equation, and fluid sound velocity derivative state equation are adopted to study motion law of fluid or fluid–solid coupling, rather than the Navier–Stokes equation in traditional fluid mechanics. Results on classical shear flow in a cavity based on the proposed granule hydrodynamics method agree well with those based on finite difference method and smoothed particle hydrodynamics method, which verifies the validity and feasibility of the granule hydrodynamics method. Two more numerical examples of solid–fluid coupling of a multiple moving solid system are also provided, which proves the feasibility, convenience, and uniqueness of the proposed method.

scholarly journals DebrisInterMixing-2.3: a Finite Volume solver for three dimensional debris flow simulations based on a single calibration parameter – Part 1: Model description

2015 ◽  
Vol 8 (8) ◽  
pp. 6349-6378 ◽  
Author(s):  
A. von Boetticher ◽  
J. M. Turowski ◽  
B. W. McArdell ◽  
D. Rickenmann ◽  
J. W. Kirchner
Keyword(s):  
Fluid Dynamic ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Clay Content ◽  
Friction Angle ◽  
Navier Stokes ◽  
Rheological Parameters ◽  
Model Description ◽  
Navier Stokes Equation ◽  
Dependent Flow

Abstract. Here we present a three-dimensional fluid dynamic solver that simulates debris flows as a mixture of two phases (gravel and fine material suspension) with a third unmixed phase representing the air and the free surface. We link all rheological parameters to the material composition, i.e., to water content, clay content and mineral composition, content of sand and gravel, and the gravel's friction angle; the user must specify only a single free model parameter. The Volume-Of-Fluid (VOF) approach is used to combine the three phases into a single cell-averaged Navier–Stokes equation for incompressible flow, based on code adapted from standard solvers of the Open-Source CFD software OpenFOAM. We present a stable implementation of a Coulomb-Viscoplastic model that represents the pressure-dependent flow behavior of the granular phase, and a Herschel–Bulkley representation of the interstitial fluid. The VOF method saves computational costs compared to drag-force based multiphase models. Thus depth-averaging is not necessary and complex three-dimensional flow structures can be simulated.

Effect of the Cross-Sectional Shape of Recirculation Channel on Expelling Air Bubbles in the FDBs of HDD Spindle Motors

2014 ◽  
Author(s):  
Y. H. Jung ◽  
G. H. Jang ◽  
C. H. Kang ◽  
H. H. Shin ◽  
J. Y. Jeong
Keyword(s):  
Fluid Dynamic ◽  
Hard Disk Drives ◽  
Navier Stokes ◽  
Air Bubbles ◽  
Navier Stokes Equation ◽  
Cross Sectional ◽  
Air Bubble ◽  
Trapped Air ◽  
Large Pressure ◽  
Fast Flow

Fluid dynamic bearings (FDBs) are applied to most of the spindle motors of computer hard disk drives (HDDs) since FDBs provide better dynamic characteristics, such as lower vibration and noise, than ball bearings. However, a weakness of FBDs is instability arising from air bubbles in the oil lubricant of FDBs. One possible solution to expel the trapped air bubbles out of FDBs is to include recirculation channel (RC). RC is designed to balance the pressures between upper and lower parts of FDBs and to circulate the oil lubricant as well as to expel air bubbles out of FDBs. This paper experimentally and numerically investigates the behavior of the air bubble in oil lubricant of operating FDBs due to the design of the RC. We created the FDBs with transparent cover and performed the experiment to visually observe the behavior of trapped air bubbles. Also, we numerically studied the phenomena of expelling the air bubble. The flow field of FDBs is calculated by the Navier-Stokes equation and the continuity equation. And we numerically explained that large pressure difference between upper and lower regions of RC and fast flow velocity along RC expel the air bubble out of FDBs. This research can be effectively utilized to develop robust FDBs by expelling the air bubbles out of FDBs.

Particle Tracking Computational Prediction of Hemolysis by Blade of Micro-Axial Blood Pump

2010 ◽  
Vol 160-162 ◽  
pp. 1779-1786
Author(s):  
Xin Chen ◽  
Jian Ping Tan ◽  
Zhong Yun
Keyword(s):  
Blood Flow ◽  
Fluid Dynamic ◽  
Computational Prediction ◽  
Blood Pump ◽  
Navier Stokes ◽  
Initial Attempt ◽  
Navier Stokes Equation ◽  
Artificial Blood ◽  
Blood Damage ◽  
Blood Pumps

By analyzing fluid dynamics of blood in an artificial blood pump and simulating the flow field structure and the flow performance of blood, the blood flow and the damages in the designed blood pump would be better understood. This paper describes computational fluid dynamic (CFD) used in predicting numerically the hemolysis of blade in micro-axial blood pumps. A numerical hydrodynamical model, based on the Navier-Stokes equation, was used to obtain the flow in a micro-axial blood pump. A time-dependent stress acting on blood particle is solved in this paper to explore the blood flow and damages in the micro-axial blood pump. An initial attempt is also made to predict the blood damage from these simulations.

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