Magnetohydrodynamic forces

In microfluidics, control and manipulation of fluid flow can be accomplished by pressure-driven, electrokinetic, magnetohydrod3mamic, centrifugal, and capillary forces. When forces such as electrokinetic and magnetohydrodynamic forces act on the walls of a microcharmel, a slip in the fluid flow occurs at the walls. On the other hand, when forces such as pressure-driven forces act on the inlet or outlet, a laminar flow of fluid experiences no slip at the walls. Thus, the middle of the charmel flows at a higher velocity than near the... 

The generation of a stable and controllable fluid flow in microfluidic devices is a major issue, and a lot of research work has been put into optimizing the flow driving methods. Not only conventional methods (derived from macroscopic applications) like pressure-driven and electroosmotic flows have been scaled down, but also novel methods like shear-driven flows (SDF) have been introduced. There are several problems associated with the conventional flow driving methods pressure-driven flows suffer from pressure drop limitations, while electroosmotic flows suffer from Joule heating, fluctuations of flow velocity, and double-layer overlap [1]. Therefore, other approaches to evade these problems and limitations have been proposed (centrifugal forces, magnetohydrodynamic forces, etc.). 

The influence of the induced current on the magnetic field results in establishing of the Lorenz (magnetohydrodynamic) force (F) (Gillon, 2000 Vives Ricou, 1985) ... 

The Hall Effect, in magnetohydrodynamics (MHD), rotates the current vector away from the direction of the electric field and generally reduces the level of the force that the magnetic field exerts on the flow. It is usually measured by the parameter cor, where co = eB/m is the angular velocity of the electron orbits around the field lines, and r is the mean time between scattering collisions for the electrons. The form of Ohm s law which accounts for the Hall Effect (See Ref 2a) is ... 

Magnetic effects in electrolytic processes have always held a special if somewhat distant interest for electrochemists. In Chapter 5, by Fahidy, an excellent account is given of the fundamentals of this topic and its applications, through magnetohydrodynamics, to electrodeposition and corrosion. Also treated is the basis of the electrolytic Hall effect, which is essential for understanding how electrohydrodynamic forces act on moving ions in a magnetic field. 

Magnetic fields/ Lorentz forces Magnetohydrodynamic stirring (e.g., Bau et al. 2001)... 

As dimension shrinks, the surface area to volume ratio increases by orders of magnitude. Many forces or fields, which are not significant in macroscale fluid flow, become important in manipulating and controlling fluids in microfiuidics. These effects include thermal capillary effect, electroosmosis, surface tension, and magnetohydrodynamics. These forces or fields provide us alternative means to control the microfiuidic flow behaviors. The electroosmosis has been applied and investigated by some researchers. Gao et al. [5] and Wang et al. [6] developed a theoretical model to predict... 

As an application example, in the field of magnetohydrodynamics, the profile sensor measured the temporal evolution of the velocity field near the electrode at a copper electrolysis experiment under the influence of a magnetic field in order to study the interaction between Lorentz force and buoyancy-driven convection [6]. 

Aogaki R, Fueki K, Mukaibo T (1975) Application of magnetohydrodynamic effect to the analysis of electrochemical reactions-2. Diffusion process in MHD forced flow of electrolyte solutions. Denki Kagaku 43 509-514... 

Following the Magnetohydrodynamics (MHD) theory, the equation of equilibrium (the equation of force balance) is... 

Fluids influenced by external force fields are best exemplified by systems in which electrically conducting fields play a role (for example, magnetohydrodynamics). In such cases,... 

Magnetohydrodynamic sUrring Centrifugal forces Acoustic streaming... 

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