Specific features of non-Newtonian magnetorheological fluid flow in the workpiece–instrument gap of a polishing facility

2017 ◽  
Vol 29 (1) ◽  
pp. 116-124
Author(s):  
Evguenia V Korobko ◽  
Albert A Mokeev ◽  
Anastasiya V Kryt ◽  
Egidijus Dragašius ◽  
Andrei A. Mokeev
Keyword(s):  
Magnetic Field ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Strength Distribution ◽  
Navier Stokes ◽  
Inlet Section ◽  
Navier Stokes Equation ◽  
Polishing Fluid ◽  
Magnetorheological Polishing Fluid ◽  
Magnetorheological Polishing

The model of magnetorheological polishing fluid flow has been developed in the form of a jet formed in the gradient magnetic field in the gap between the workpiece and the instrument of a polishing facility. The model allows one to determine the shape of the transverse and longitudinal sections of the jet and the pressure acting on the workpiece surface being polished, while accounting for the known configuration of the gap and magnetic field strength distribution. The appearance of the nose surf and the stern concurrent wave producing an additional pressure drop in the workpiece–instrument gap has been established. The solution of the Navier–Stokes equation in the approximation of lubrication for magnetorheological polishing fluid with boundary conditions accounting for the action of inertial forces has shown that in the inlet section of the gap the pressure drop is positive, and the velocity profile is almost flat near the workpiece, whereas closer to the outlet from the gap, the pressure falls below the atmospheric pressure. The pressure is maximum at the forward edge of the workpiece, as in the case of the well-known phenomenon of hydroplaning.

scholarly journals Nonlinear Dynamos

2010 ◽  
Vol 6 (S271) ◽  
pp. 297-303
Author(s):  
David Galloway
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Stokes Equation ◽  
Lorentz Force ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Direct Competition ◽  
Astrophysical Objects ◽  
Flow Domain ◽  
The Magnetic Field

AbstractThis paper discusses nonlinear dynamos where the nonlinearity arises directly via the Lorentz force in the Navier-Stokes equation, and leads to a situation where the Lorentz force and the velocity and the magnetic field are in direct competition over substantial regions of the flow domain. Filamentary and non-filamentary dynamos are contrasted, and the concept of Alfvénic dynamos with almost equal magnetic and kinetic energies is reviewed via examples. So far these remain in the category of toy models; the paper concludes with a discussion of whether similar dynamos are likely to exist in astrophysical objects, and whether they can model the solar cycle.

Toward a Global Model for FSI in Tube Bundles

2008 ◽  
Author(s):  
Daniel Broc ◽  
Marion Duclercq
Keyword(s):  
Fluid Flow ◽  
Euler Equations ◽  
Dynamic Behaviour ◽  
Navier Stokes ◽  
Inertial Effects ◽  
Navier Stokes Equation ◽  
Dissipative Effects ◽  
Tube Bundles ◽  
Homogenization Methods ◽  
Physical Phenomena

It is well known that a fluid may strongly influence the dynamic behaviour of a structure. Many different physical phenomena may take place, depending on the conditions: fluid at rest, fluid flow, little or high displacements of the structure. Inertial effects can take place, with lower vibration frequencies, dissipative effects also, with damping, instabilities due to the fluid flow (Fluid Induced Vibration). In this last case the structure is excited by the fluid. The paper deals with the vibration of tube bundles in a fluid, under a seismic excitation or an impact. In this case the structure moves under an external excitation, and the movement is influenced by the fluid. The main point in such system is that the geometry is complex, and could lead to very huge sizes for a numerical analysis. Many works has been made in the last years to develop homogenization methods for the dynamic behaviour of tube bundles (/2/ and /3/). The size of the problem is reduced, and it is possible to make numerical simulations on wide tubes bundles with reasonable computer times. These homogenization methods are valid for “little displacements” of the structure (the tubes), in a fluid at rest. The fluid movement is governed by the Euler equations. In this case, only “inertial effects” will take place, with globally lower frequencies. It is well known that dissipative effects due to the fluid may take place, even if the displacements of the tube are no so high, or if the fluid is not still (/4/, /5/, /6/ and /8/). Such effects may be described in the homogenized models by using a Rayleigh damping, but the basic assumption of the model remains the “perfect fluid” hypothesis. It seem necessary, in order to get a best description of the physical phenomena, to build a more general model, based on the general Navier Stokes equation for the fluid. The homogenization of such system will be much more complex than for the Euler equations. The paper doesn’t pretend to give a general solution of the problem, but only points out the most important key points to build such homogenized model for the dynamic behaviour of tubes bundles in a fluid.

scholarly journals Mathematical modelling of fluid flow in electromagnetically stirred weld pool

2021 ◽  
Vol 1201 (1) ◽  
pp. 012025
Author(s):  
K Enger ◽  
M G Mousavi ◽  
A Safari
Keyword(s):  
Fluid Flow ◽  
Grain Refinement ◽  
Weld Pool ◽  
Fluid Velocity ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Turbulent Fluid Flow ◽  
Flow Modelling ◽  
Weld Parameters ◽  
The Relationship

Abstract In this paper, a mathematical model has been proposed to study the relationship between electromagnetic stirring (EMS) weld parameters and the mode of fluid flow on grain refinement of AA 6060 weldments. For this purpose, fluid flow modelling using Navier-Stokes equation is described first, and then, the proposed mathematical approach has been discussed in detail. For demonstration, calculations to determine the fluid velocity in the weld pool of thin plate AA6060 were performed. The application of the model on the experimental results indicates that the best grain refinement is achieved at a transition mode from laminar to turbulent fluid flow.

scholarly journals SIMULATION OF HYDRO-MECHANICAL PROCESSES IN CENTRIFUGAL PUMPS

2016 ◽  
Vol 2016 (1) ◽  
pp. 100-105
Author(s):  
Ризван Шахбанов ◽  
Rizvan Shakhbanov ◽  
Леонид Савин ◽  
Leonid Savin
Keyword(s):  
Fluid Flow ◽  
Continuity Equation ◽  
Equation Of Motion ◽  
Theoretical Description ◽  
Navier Stokes ◽  
Centrifugal Pumps ◽  
Navier Stokes Equation ◽  
Rotary Pumps ◽  
Rotating Coordinates ◽  
Graphical Presentation

The peculiarities in current and kinematics of hydromechanical processes in centrifugal (rotary) pumps are considered. The theoretical description and graphical presentation of velocity profiles in an impeller are shown. A complex current in an impeller is described with the aid of a continuity equation and Navier-Stokes equation for rotating coordinates. A nonviscous character of fluid flow in the setting of an im-peller is taken into account by means of averaging of the equation of motion for that purpose the equation of a turbulence model is introduced in addition. The scheme of the digitization of a modeling area with the aid of a volumetric endelement grid is presented. As an example a computer model as a part of an impeller is shown.

scholarly journals A MAGNETOHYDRODYNAMIC STUDY OF BEHAVIOR IN AN ELECTROLYTE FLUID USING NUMERICAL AND EXPERIMENTAL SOLUTIONS

2012 ◽  
Vol 11 (1-2) ◽  
pp. 53
Author(s):  
L. P. Aoki ◽  
M. G. Maunsell ◽  
H. E. Schulz
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Fluid Velocity ◽  
Flow Analysis ◽  
Test Chamber ◽  
Cross Product ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Vector Density ◽  
The Magnetic Field

This article examines a rectangular closed circuit filled with an electrolyte fluid, known as macro pumps, where a permanent magnet generates a magnetic field and electrodes generate the electric field in the flow. The fluid conductor moves inside the circuit under magnetohydrodynamic effect (MHD). The MHD model has been derived from the Navier Stokes equation and coupled with the Maxwell equations for Newtonian incompressible fluid. Electric and magnetic components engaged in the test chamber assist in creating the propulsion of the electrolyte fluid. The electromagnetic forces that arise are due to the cross product between the vector density of induced current and the vector density of magnetic field applied. This is the Lorentz force. Results are present of 3D numerical MHD simulation for newtonian fluid as well as experimental data. The goal is to relate the magnetic field with the electric field and the amounts of movement produced, and calculate de current density and fluid velocity. An u-shaped and m-shaped velocity profile is expected in the flows. The flow analysis is performed with the magnetic field fixed, while the electric field is changed. Observing the interaction between the fields strengths, and density of the electrolyte fluid, an optimal configuration for the flow velocity isdetermined and compared with others publications.

scholarly journals Stability of an Axisymmetric Liquid Metal Flow Driven by a Multi-Pole Rotating Magnetic Field

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 77 ◽  
Author(s):  
Tagawa ◽  
Song
Keyword(s):  
Magnetic Field ◽  
Velocity Profile ◽  
Stokes Equation ◽  
Hartmann Number ◽  
Metal Flow ◽  
Basic Flow ◽  
Rotating Magnetic Field ◽  
Navier Stokes ◽  
Force Term ◽  
Navier Stokes Equation

The stability of an electrically conducting fluid flow in a cylinder driven by a multi-pole rotating magnetic field is numerically studied. A time-averaged Lorentz force term including the electric potential is derived on the condition that the skin effect can be neglected and then it is incorporated into the Navier-Stokes equation as a body force term. The axisymmetric velocity profile of the basic flow for the case of an infinitely long cylinder depends on the number of pole-pairs and the Hartmann number. A set of linearized disturbance equations to obtain a neutral state was successfully solved using the highly simplified marker and cell (HSMAC) method together with a Newton–Raphson method. For various cases of the basic flow, depending on both the number of pole-pairs and the Hartmann number, the corresponding critical rotational Reynolds numbers for the onset of secondary flow were obtained instead of using the conventional magnetic Taylor number. The linear stability analyses reveal that the critical Reynolds number takes its minimum at a certain value of the Hartmann number. On the other hand, the velocity profile for cases of a finite length cylinder having a no-slip condition at the flat walls generates the Bödewadt boundary layers and such flows need to be computed including the non-linear terms of the Navier-Stokes equation.

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