The relation between the macroscopic theory of dense ferrofluids and the microscopic theory of dilute ferrofluids is discussed. It is shown that the dense and dilute regimes must be carefully distinguished. Shliomis’s approximate theory for dilute ferrofluids does not apply in the dense regime, and has limited validity in the dilute regime.

• Received 26 April 2001

DOI:https://doi.org/10.1103/PhysRevE.64.063502