MHD & EHD

What are ElectroHydroDynamics (EHD) and MagnetoHydroDynamics (MHD)?

Electrohydrodynamics (EHD), also known as electro-fluid-dynamics (EFD) or electrokinetics, is the study of the dynamics of electrically conducting fluid. It studies the motions of ionized particles or molecules and their interactions with electric fields and the surrounding fluid. The term may be synonymous with the rather elaborate electrostrictive hydrodynamics. EHD covers the following types of particle and fluid transport mechanisms: Electrophoresis, electrokinesis, dielectrophoresis, electro-osmosis, and electrorotation. The phenomena are related to the direct conversion of electrical energy into kinetic energy and vice versa. In the first instance, shaped electrostatic fields create hydrostatic pressure (or motion) in dielectric media. When such media are fluids, a flow is produced. If the dielectric is a vacuum or a solid, no flow is created. Such flow can be directed against the electrodes, generally to move the electrodes. In such a case, the moving structure acts as an electric motor. Practical fields of interest of EHD are the common air ionizer, Electrohydrodynamic thrusters, and EHD cooling systems. In the second instance, the converse takes place. A powered flow of medium within a shaped electrostatic field adds energy to the system, which electrodes pick up as a potential difference. In such a case, the structure acts as an electrical generator.

Magnetohydrodynamics (MHD; also magneto-fluid dynamics or hydro magnetics) study electrically conducting fluids’ magnetic properties and behavior. Examples of magneto fluids include plasmas, liquid metals, salt water, and electrolytes. The word “magneto­hydro­dynamics” is derived from the magneto- meaning magnetic field, hydro- meaning water, and dynamics meaning movement. The simplest form of MHD, Ideal MHD, assumes that the fluid has so little resistivity that it can be treated as a perfect conductor. In ideal MHD, Lenz’s law dictates that the fluid is in a sense tied to the magnetic field lines. To explain, in an ideal MHD, a small rope-like volume of fluid surrounding a field line will continue to lie along a magnetic field line, even as it is twisted and distorted by fluid flows in the system. This is sometimes referred to as the magnetic field lines being “frozen” in the fluid. The connection between magnetic field lines and fluid in ideal MHD fixes the topology of the magnetic field in the fluid—for example, if a set of magnetic field lines are tied into a knot, then they will remain so as long as the fluid/plasma has negligible resistivity. This difficulty in reconnecting magnetic field lines makes it possible to store energy by moving the fluid or the magnetic field source. The energy can become available if the conditions for ideal MHD break down, allowing magnetic reconnection that releases the stored energy from the magnetic field.

MHD and EHD simulations in ANSYS Fluent software

The Magnetohydrodynamics (MHD) and Electrohydrodynamics (EHD) modules are added to the standard ANSYS FLUENT licensed software. The ANSYS FLUENT MHD-EHD model allows you to analyze electrically conducting fluid flow behavior under the influence of constant (DC) or oscillating (AC) electromagnetic fields. The externally-imposed magnetic field may be generated by selecting simple built-in functions or importing a user-supplied data file. For multiphase flows, the MHD, EHD model is compatible with the discrete phase model (DPM), the volume-of-fluid (VOF), and Eulerian mixture approaches in ANSYS FLUENT, including the effects of a discrete phase on the electrical conductivity of the mixture.

MR-CFD, an expert in the field of MHD-EHD simulations

With several years of experience simulating a wide range of problems in various CFD fields using Fluent software, the MR-CFD team is ready to offer extensive modeling, meshing, and simulation services. Simulation Services for MHD-EHD simulations are categorized as follows:

  • CFD simulation of Magnetic Field Effect on Nanofluid Heat Transfer
  • CFD simulation of MHD Effect on Fluid Flow
  • CFD simulation of Magnetic Force Effect on an Airfoil

Our services are not limited to the mentioned subjects, and the MR-CFD team is ready to undertake different and challenging projects in the MHD-EHDfield ordered by our customers. You can consult with our experts freely and without charge at first, and then order your project by sending the problem details to us using the following address.

[email protected]

By entrusting your project to the MR-CFD team, you will not only receive the related project’s files (Geometry, Mesh, Fluent files). Also, you will be provided with an extensive tutorial video demonstrating how you can create the geometry, mesh, and define the needed settings in the Fluent software all by yourself. And these all come with post-technical support from the MR-CFD team.

MR-CFD experts are ready to fulfill every Computational Fluid Dynamic (CFD) needs. Our service includes industrial and academic purposes considering a wide range of CFD problems. MR-CFD serves in three main categories: ANSYS Fluent Consultation, ANSYS Fluent Training, and ANSYS Fluent Project Simulation. MR-CFD company has gathered experts from various engineering fields to ensure the quality of CFD services. Your CFD project would be done in the shortest time, with the highest quality and reasonable cost.

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