Fluid flows attract attention from several different fields of science that span over length scales, ranging from conventional physical chemistry, mechanical and chemical engineering to environmental and biomedical sciences in more recent years. Recent technical advances in experimental fluid mechanics have not only paved the path to address fluidic problems across many length/time scales but also allowed crossing boundaries of various scientific disciplines. In this talk, I will report findings from few of such experimental investigations in the context of cleaning applications. Here, cleaning refers to the general process of removal of impurities in particulate or continuous form from fluid mixtures or solid substrates. I will first introduce a variety of physical interfacial cleaning processes for removal and filtration of contamination. Secondly, I will cover the conventional surfactant-based approach and the corresponding complex molecular self-assemblies that significantly affect its overall cleaning efficiency. In this context, I will discuss experimental observations that link molecular length-scales to micro/macroscopic flow behaviour. From the academic point of view, the source of contamination and cleaning technology often define the scientific disciplines and experimental characterisation approaches involved. Therefore, cleaning processes naturally represent great examples of interdisciplinary fluid mechanic problems that demand fundamental understanding of chemistry, physics and microbiology across many length scales.