NMR for Equilateral Triangular Geometry under Conditions of Surface   Relaxivity - Analytical and Random Walk Solution
  We consider analytical and numerical solution of NMR relaxation under the condition of surface relaxation in an equilateral triangular geometry. We present an analytical expression for the Green's function in this geometry. We calculate the transverse magnetic relaxation without magnetic gradients present, single-phase, both analytically and numerically. There is a very good match between the analytical and numerical results. We also show that the magnetic signal from an equilateral triangular geometry is qualitatively different from the known solution: plate, cylinder and sphere, in the case of a nonuniform initial magnetization. Non uniform magnetization close to the sharp corners makes the magnetic signal very fast multi exponential. This type of initial configuration fits qualitatively with the experimental results by Song et al.[1]. It should also be noted that the solution presented here can be used to describe absorption of a chemical substance in an equilateral triangular geometry (for a stationary fluid). 
J. Finjord, A. Hiorth, U. H. a Lad and S. M. Skjaeveland