Separate treatment of the gap in finite element analysis of recording heads

Complete 3D finite element analysis of recording heads is strongly restricted by the number of elements needed, even for relatively simple geometries. The large difference in scale between the gap and the overall size of the head makes a continuous mesh of any accuracy very difficult to achieve. One is hence forced to decompose into different subdomains, while assuring their mutual dependence by a choice of appropriate boundary conditions. We propose to replace the gap area for the overall analysis by a "permeable wall condition". An iterative algorithm is needed to solve for the total domain. We studied a 2D sample problem and compared with a complete mesh. Good agreement of results was found after only one full iteration.