we kow the electrode volume for a known dimensions of a rotating cylinder. so, in the case of scale up, we can use the volumetric density of electrical current. which stay constant in all cases of dimensions.
Thank you for your answer, different types of rotating cylinder electrode may be involved for example the smooth rotating electrode and three dimensional rotating electrodes which may be either porous or nets electrodes, in this case the current and potential distributions are entirely different at each electrode, so when scale-up we consider only the dimensions similarity or there are other criteria that I want to know