 In these expressions, formula_5 is the fluid density, formula_6 is the fluid zero shear viscosity, formula_7 is the surface tension, formula_8 is the initial radius of the jet, and formula_9 is the relaxation time associated with the polymer solution., where (z, t) is the axial velocity; formula_10 and formula_11 are the solvent and polymer contribution to the total viscosity, respectively (total viscosity formula_12); formula_13 indicates the partial derivative formula_14 ; formula_15 and formula_16 are the diagonal terms of the extra-stress tensor.Equation (1) represents mass conservation, Equation (2) represents momentum equation in one dimension.