## General Mechanical

#### Fluent MHD module

• ashokuvce1526
Subscriber
Hello all

Can anyone please share the tutorials for fluent MHD for parallel plate flow.
Regards
• ashokuvce1526
Subscriber

I am simulating the flow between the parallel plates in ansys fluent MHD module. The fluid used here is MR Fluid. The model that i used is below, after applying magnetic field in the y-direction in MHD dialog box(B0_y component) the velocity is not decreasing.

Can someone helpme out to solve this problem.

Thanks and regards.

• Rob
Ansys Employee

Unless there's a tutorial bundled with the documentation we can't share the materials. I'm not familiar with the MHD module, but what have you set that would slow the flow down?

• jj77
Subscriber
This reminds me of a emag flow meter. If this was a pipe you would get a voltage difference in the z out of plane direction, and that potential is proportional to the flow. That is it, never heard that it influences the flow otherwise emag flow meters would not work and trust me they do.

But MR seems different. This paper is OK, compare speed at centre of pipe for different B fields and you should see an effect if you model the material correctly (with emag properties)

Search for this

Web results
Magnetohydrodynamic Flow of Liquid-Metal in Circular Pipes for ...
• ashokuvce1526
Subscriber

conditions are: pressure inlet= 500Pa

viscosity        = 0.042Kg/ms

density=2380Kg/m3

Permeability = 4h/m.

Two-dimensional CFD simulation of magnetorheological fluid between two

# Two-dimensional CFD simulation of magnetorheological fluid between twofixed parallel plates applied external magnetic field

##### Two-dimensional CFD simulation of magnetorheological fluid between twofixed parallel plates applied external magnetic field
• ashokuvce1526
Subscriber

Gedik, E., Kurt, H., Recebli, Z., & Balan, C. (2012). Two-dimensional CFD simulation of magnetorheological fluid between two fixed parallel plates applied external magnetic field. Computers & fluids63, 128-134.

I am trying to simulate exact paper results for my practice.

Thanks and regards

• ashokuvce1526
Subscriber

Gedik, E., Kurt, H., Recebli, Z., & Balan, C. (2012). Two-dimensional CFD simulation of magnetorheological fluid between two fixed parallel plates applied external magnetic field. Computers & fluids63, 128-134.

I trying to simulate the same paper conditions.

Thanks

• ashokuvce1526
Subscriber

directly i am going to fluent MHD module. Before that i have to do any magnetostatic analysis and the results should be coupled with Ansys fluent MHD module?

Regards

• jj77
Subscriber

I tried this type of example and I can not get it to work/give the results as needed - do not have much experience with fluent mhd .

Perhaps some of the Ansys guys can help.

• Rob
Ansys Employee

With those boundary conditions the result looks sensible: how would the magnetic field alter the flow? I also don't have those papers (don't share unless it's an open source, and recognisable, link) so no idea what it's doing.

• jj77
Subscriber
There is a force in the flow direction (opposes flow) that is proportional to the square of the external magnetic field (Hartmann flow the Hartmann number is the ratio between this force and viscous forces) . I can see the applied field but I do not get any force
• ashokuvce1526
Subscriber

Applying magnetic increases the viscosity of the fluid inturn reducing the velocity of the fluid.

• jj77
Subscriber

As per previous post the magnetic field results in a Lorentz force opposing the fluid flow, it doesn't not change the viscosity at least in standard incompressible Hartmann flow. The ratio between the Lorentz force due to the magnetic field and the viscous forces is THE Hartmann number. Look up Hartmann flow between parallel plates and see the derivation. One needs a good understanding of both Emag and fluid mechanics to understand it. A lot of material on the subject online.

Google search the below words and look say on the 5th hit, that is a pdf called 4.pdf from ijpam which explains it all:

hartmann flow between parallel plates

• jj77
Subscriber

I think the problem why I could not see any Force (Lorentz), induced voltage or current density is because it does not work with steady state.

If the fluent transient solver is used then it works and all the above are finally present.

Did a small benchmark (openfoam mhd tutorial - 2.3 MHD flow of a liquid), and it works fine see below (upper no B field and lower with By=20 T).