Solution Method

pmcardle

I have a multilayered nano antenna that I want to simulate in the THz frequency range. A thin layer of platinum on a silicon core, I originally used the SEP to simulate the platinum and silicon layers but would like to bench mark it against a volumetric solution method ( FEM/VEP). Reason being the platinum layer thickness is less then the skin depth at the frequencies I am simulating. The Mesher does not like the platinum layer so I am stuck. Any suggestions are on a way to ensure my original results with the SEP are accurate independent of using the FEM/VEP? 

Altair Forum User

Hi @pmcardle

 

Could you be more specific with the meshing problem that you have - is there an error? Alternatively, please attach the .cfx file so that we can take a look.

JIF

Hell pmcardle,

 

It really helps if you can provide the model or at least a few images.

 

Regarding your question, I can try to assist with the information that you provided. Since you are working with a very small model, the first thing that I would suggest is that you set the model unit appropriately so that you don't work with very small numbers in your model. I would also suggest that you reduce the model extents to better fit the model size. These two actions will ensure that you don't run into tolerance issues - that could be the meshing problem. These are just suggestions and wild guesses, since I don't have the model.

 

If yo model the platinum as a sheet with the appropriate thickness set on the face, the SEP solution should be very accurate since it will model a single current on the face with the correct resistance, taking the skin effect into account. This is the case for a very thing face, where the skin depth is much less than the thickness. On the other side of the spectrum (not your case), where the the skin depth is much smaller than the region, the answer will also be accurate. Where you need to be careful, is when the skin depth is roughly the same as the thickness. In that case it is probably required to model the face as a finite thickness region (thus, faces on both sides). The reason for this is that the currents on the two sides are probably comparable, but you want to model them as two currents and not as a single current (an example could be that the current on the one face could be half that of the current on the other side). When modelling finite thickness sheets, a general rule of thumb is that your mesh elements should not be larger than the distance between the two faces. That means that the lower the thickness, the smaller the required mesh.

 

Above I have assumed that you model the platinum as a metal. If you are trying to model it as a dielectric (with equivalent material properties), then you can use FEM / VEP, but your meshing requirements will go up (probably a lot).

 

You have already asked similar questions in the linked topic. We won't be able to help you without the model or an equivalent model (if you can't share the actual model).