A general boundary‐integral formulation for zoned three‐dimensional media

A new boundary‐integral formulation is proposed to analyse the heat transfer in zoned three‐dimensional geometries. The proposed formulation couples the boundary formula, the gradient of the boundary formula and the exterior formula. An advantage of this method over the traditional methods is that any linear condition at the interface between subdomains may be incorporated into the formulation at the outset. In addition, the new method provides a sparse and well‐conditioned matrix of coefficients with a minimum number of equations.