Learning Forum

[Sara Alao]

Hi,

I have been needing to use Ansys Fluent and the MHD module provided with the License of the product for my work. I am having issues with my fluid flow model, as the flow does not seem to react with the electric potential being inserted.

I have set the boundary conditions on the elements used, giving them an electric potential difference, which through experimental work does show its effect the fluid flow. I have changed the material properties to ensure that the electric permeability was taken into account, of the fluid and the solids being used. I have also simplified the model to 2D from 3D and changed the spacing of the elements, and resolution of the mesh.

There is no notable change in the results when the EHD and Energy models are switched on or off.

I have followed the Ansys Customer guide on this particular module when setting up my model, but it is not able to produce relevant results.

Let me know if it would be possible to help regarding this topic.

Many thanks.

[Konstantin]

 

That’s correct if you are not imposing an external magnetic field. The electric potential method solves the electric potential equation (see Sec. 22.3. Electric Potential Method of the Theory Guide), which is then used to calculate current j. The electric potential approach does not solve for the magnetic field. The Lorentz force is given by: F = j x B, which will be zero unless an external magnetic field is prescribed, hence no effect of the electric potential on the fluid. The electric potential will have an effect on charged DPM particles, however. 

You should consider the magnetic induction method which will calculate induced magnetic field and give a non-zero Lorentz force.