Optical transmission changes in ferrofluids when exposed to magnetic fields are difficult to predict: under similar conditions, exposure to a magnetic field may cause increasing, decreasing or even non monotonous optical transmission evolution in different samples. Absence or presence of coalescence has been conjectured as the key phenomenon that causes the different behaviors, but to our knowledge without any theoretical support. In the first part of this work, experimental data are provided in order to illustrate the different possible trends that may be observed. In the second part, a set of some thousands of particles is considered in different arrangements: distributed at random, grouped in single chains or with aggregates of several chains. The optical transmission of each arrangement is obtained by means of the CST software. The numerical results obtained provide a theoretical connection between the optical transmission experimental trends observed and the processes of chain formation and aggregation by coalescence, which facilitates a much deeper understanding of the phenomena observed.

当暴露在磁场中时，铁磁流体的光传输变化很难预测：在类似条件下，暴露在磁场中可能导致不同样品中光传输的增加，减少甚至非单调。据推测，缺乏或存在合并是导致不同行为的关键现象，但是据我们所知，没有任何理论支持。在这项工作的第一部分中，提供了实验数据以说明可能观察到的不同可能趋势。在第二部分中，以不同的排列方式考虑了几千个粒子的集合：随机分布，分组为单链或由多条链的聚集体组成。每种配置的光传输均通过CST软件获得。