Finite Strain from Orientational Fluctuation of Ellipsoidal Particulate Axes: Combination of Sine and Cosine Functions

Under large finite tectonic deformation and under a condition of low viscosity contrast, the axial orientational fluctuation method based on sine functions alone underestimates the values of a and b measured in the field. It is found that a better estimate of a and b and therefore of Rs could be obtained by using both sine and cosine functions. The parameters l, m and n introduced never equalise a, b and k respectively except when k = n = 0 (I = 1, m = α, k = n = 1 (1 = m but both greater than unity) and k = n = α (1 = α, m = 1). Usage of this method enhances the latitude of the ratios based exclusively on sine functions, thereby giving higher values of a and b despite small degree of orientational fluctuation of axes of ellipsoidal particles.