Forensic fluid dynamics: Insights into science of flow.

This article focuses on applying fluid dynamics principles to forensic ink analysis, examining how inks of different viscosities spread and absorb on paper and cloth surfaces. Using stereomicroscopy and capillary tube experiments, the study analyzes ink dispersion patterns and flow times for gel, rollerball, and fountain pen inks from various brands, highlighting differences in viscosity, adhesion, and wettability. Jurin's law, which relates to capillary action, and the diffusion equation are employed to mathematically model ink spread, providing insights into ink behavior on porous substrates. The findings suggest that understanding these fluid dynamic properties can aid forensic experts in distinguishing ink types, identifying writing instruments, and detecting document forgery. Limitations include a limited ink sample variety and the influence of real-world factors such as surface irregularities and environmental conditions on ink behavior.