[ajbroadbent]

Hi there,

I am trying to run a simulation of the electric field strength at the tip of an array of conical shaped "needles" with hemispherical tips in ANSYS Maxwell 3D (ANSYS Maxwell 18), specifically looking at how field strength is affected by the spacing between needles. I am having issues with the mesh generation when the spacing gets to 20 um. To give a run-down of my setup: I have a 5x5 array of needles that has been cut down to 1/4 size (2.5 x 2.5) since the layout is symmetrical. Symmetry boundaries have been applied to the sides where the array was cut, a voltage has been applied to the needles and face at the needle base, and a "ground" voltage of 0 has been applied to the face opposite the needles.

When I ran the simulation with a spacing of 20 um, the mesh of the needle tips along the symmetry boundaries had large gaps and produced areas where the simulation did no solve. I have tried changing or applying various mesh refinement settings with no success in getting a uniform mesh generated. Unfortunately, I am the only one with a Maxwell license at my school as it was acquired specifically for my research, and no one has any prior experience with this particular package. I have tired searching through Maxwell's documentation and online, but have not been able to find anything on how to solve the issue. Everything has been modeled within Maxwell. I tried seeing if I could import a mesh from ANSYS workbench, but had no success with that either.

The attached pictures are screenshots of the mesh areas in question at 20 um spacing. Note how the base of the hemispherical sections begins nice and uniform, but closer to the tip the mesh beings to fall apart. The four needles inside the region and not along the boundaries all mesh properly regardless of spacing.