It should be noted that aG in the cylindrical column are the same as those in the rectangular column having the same DH. Thus, the column shape does not affect aG in the present experiments. Though further study should be carried out in the future to under- stand the reason of this coincidence, the good agreement of aG between the two geometries guarantees that the coefficients,
CR1; CR1 and CR2; CR2 , obtained for the rectangular column